RPM & Speedo stopped working
 

Hi all,

Today my RPM & Speedo on my cluster just stopped working. This did happen a little while ago and after I took out the cluster and fiddled with the wiring, it managed to start working but today there was no such luck. I have another cluster laying around and did connect it up and the same issue is persisting so it's no the cluster.

Any idea on what I can look at to try diagnose the problem?

When these clusters go bad, the speedo and tach can go out at the same time, everything on this cluster (in a sense) is controlled by the speedo board. Is this second cluster known to be guaranteed working, and recently at that? If you cant personally vouch for the extra cluster working very recently, then it's entirely possible you have two clusters on your hands needing repair. Check the guides for repairing them if you are confident with de soldering and re soldering, or send it out. Circuit Board medics were okay in the sense that they do a lot of fd cluster repairs, so they know what to look for. Downside is they took longer than I feel they should have with my cluster, though it did have issues aside from the normal capacitor issue, they still quote a certain time frame.

I could be wrong, but I'm still going to say I think its the speedo board issues that is well known on both clusters.

Thanks for your feedback SwappedNA. To be honest, the cluster itself I cannot vouch for but found it quite coincidental that the exact same issue was occurring. I'll try get a hold of a good working cluster and test.

Forgot to ask,

Do the warning lights and the Fuel/Oil pres/Coolant temp gauges work?

Yes everything else works, just the RPM & SPEEDO have stopped.

I think you will find the culprit is the cluster board needing the usual repairs. Unless you can get a known good cluster to test with, which, I'm pretty sure would confirm what I'm thinking it is anyway. I'd pull it and start the repairs, or send it to circuit board medics. I think its like 220? Mine had some faulty traces they fixed as well.

I was completely unaware of cluster medics, excited to send my cluster out asap.

They do good work in the end, however, if you daily your car, plan for extra downtime. I paid to have my cluster shipped next day air early am & dropped it off at the FedEx hub at the airport nearby just to be sure. It got there at nine am the next day. They didn't even touch it until the day after that. Then I get a call saying their normal repairs didn't work, and they were escalating it to other technicians and I'd hear back in two days (I want to say.)

I tried to call for an update, and the person that answered didn't seem to know much, and they obviously weren't the tech working on it, and It didn't seem like they were keen to go find out any information, either. They finally called me at the end of the two days and said there were some bad traces on the board they had to repair and it was finished. This was a Friday, and I paid for next day air there and back, because I needed the car running. So I asked them whats going to happen with returning the cluster. I had to pay an extra 30.00 on top of what I already paid for shipping to have Saturday delivery.

After all was said and done, the cluster was back, and is working great so far. I would consider my experience the exception, most likely. I've only had my one cluster repaired there, so I can't say if it's the norm for them, but I doubt it. My chief complaints were they advertise up front a one day turnaround. I realize they didn't have to get to it that day, but when they offer next day shipping early am, I figured that they would. Communication was eh, never got to speak to the techs doing the repairs. Which, understandably, that would slow them down, but when I worked as a tech at my job, I still called every client. The cluster had a surprise, but they still advertise one day. I'm assuming they just tried their blanket repair and when it didn't work they started looking deeper, rather than doing a full diag ahead of time. I felt like they could have at least met me halfway with not making me pay the extra for Saturday delivery, considering it already took longer than what was stated up front.

If you aren't in a rush, or don't have a cluster with a unique situation like mine, it probably will go smoothly, but plan for downtime regardless.

rexhvn,

Did you say that you swapped in another instrument cluster and the tach + speedo is still dead?

If so, then you may want to verify the flex print is making positive contact with the C1-01 connectors. Clean them with a rubber eraser, then apply rubbing alcohol to them. Afterwards, bend them towards the center of each hole. Be careful not to kink or crease them! You just want to roll them towards the center. This will ensure proper contact with the C1-01 connectors. Additionally, visually inspect the flex print for any potential damage.

Furthermore, make sure the flex print cable is connected to CON1 (the flat connector in the upper left corner that is protected by the black plastic shroud. If that is disconnected or damaged then you will not have a functioning tach or speedo.

I am currently looking into circuit board medics. My tach went out recently and odometer as well. There also looks like there is a burn mark on the odometer screen? I am trying to decide if I should follow some of the DIY videos and attempt to do the soldering myself or just use circuit board medics... I have read that many people that try and even succeed with the DYI --- it ends up dying again down the road.

circuit board medics apparently can repair it while keeping mileage. I am at 48k miles and def want to keep that! Lol

I am not seeing many reviews here on the forums for circuit board medics though

Thoughts?

Thanks bros
-Alex

See my post above. Unless you are skilled at soldering, I wouldn't recommend it. If you are skilled at soldering, You will likely find it to be a pain due to the caps being soldered to both sides of the pcb, at least that was my experience, that's why I just sent it off.

Roger that bro. That is what I am leaning towards..

Thanks!

Alex,

If your LCD screen is boogered up then they may have a problem replacing it. The only way to source a new LCD screen is to cannibalize it from another speedo. Have you removed and inspected your speedo board yet? Care to show us that burn mark on your LCD display?

Sure man. Sorry I’m new to the forums. So still learning - hopefully these uploads are not too big.

odo came back on. Then when I came back from inside the store and it was out again - and so was my tac and speedo - then after another start up speedo and tac were on but odo wasn’t :dunno:

I think maybe it’s not a “burn” because when odo displays I can in fact see the numbers.

i have not removed and inspected the board yet.

Thanks Guys. Love the FD and beginning the journey. Just got her not long ago and finished doing full fluid flush, coils rims and tires. Going to do hawk pads, StopTech rotors and steel braided lines this weekend (and brake fluid flush)

Now it’s off to the smaller things like this


https://cimg5.ibsrv.net/gimg/www.rx7...6add807a7.jpeg
https://cimg6.ibsrv.net/gimg/www.rx7...0ce8ae998.jpeg
https://cimg7.ibsrv.net/gimg/www.rx7...a4adc7429.jpeg

https://cimg3.ibsrv.net/gimg/www.rx7...00cc88698.jpeg
https://cimg5.ibsrv.net/gimg/www.rx7...ccacd5b04.jpeg

Alex,

Thanks for sharing some photos of your clean FD!

You must be referring to the circular spot on your LCD display. Right? Unfortunately, I don't know what that could be. Maybe the polarized film is goobered on the LCD screen? I've seen worse though.

Since your odo and speedo are intermittently working, I would highly recommend that you remove the cluster and inspect the speedo board. I curate a couple threads associated with this topic. While in there, take some photos of the board and post. I would also recommend applying isopropyl alcohol on a cotton swap to any leaky caps (if any) on the board. This will at least neutralize the acidic effects of the electrolyte chewing away at the solder runs and other leads. Please refer to those threads: the just found out how to fix an FD odometer and my FD Speedometer threads. They are an easy find when searching the forum.

Out of curiosity, where in NC are you?

Thanks brother!

Roger that George!! Will do!

I am about 30 minutes south of Raleigh!

-Alex

Alex,

Copy, south of Raleigh.

If you have any questions about the speedo board then don't hesitate to reach out to me or post in those threads. I may be able to advise on the problem with pics of the board.

Solid copy brother!

Will def let you know as soon as I crack it open. May be a week from now though. Possibly this weekend.

sent you a friend request

I just checked “just found out how to fix an FD odometer” —- I actually had this one saved! Lol

will def touch basis with you brother. Might not be necessary to spend hundreds of dollars - Thank you again.

What ecu are you running?

Copy all. Friend request approved.

I don't want to be all doom and gloom but the sooner you can neutralize that acid from any leaking capacitors then the less damage it will do to your circuit board. Keep in mind the speedo sits vertically so any leaky cap will ooze its acid and run down the length of the board.

Just remember to be careful when removing the cluster hood. Your 93 plastics have a greater tendency to crack.

Word. Roger that George. I’m excited to get in there.
thanks for the warm welcome man. I’m loving these forums. Getting hooked!

I will snap some pictures ASAP. Should I post them in here or in your other forum posts on the topic?

-Alex

https://cimg3.ibsrv.net/gimg/www.rx7...2884ca4d7.jpeg

Alex,

Glad to lend a hand! Make sure that the ground wires to the ECU are properly connected, in case they came loose or if you did any digging around the engine bay or ecu. You can post pics and discuss the speedo here: Troubleshooting the FD Speedometer-Odometer We can get into the weeds there.

How does that sound?

Sounds great man. So it may just be a ground wire?! Okay yes .. I’m still learning haha

I got the car from my tuner for my FC, so trusted source, but I want to learn my own and not keep buggin him.

So milage wouldn’t affect how much corrosion is on the circuit board would there? Being that it has less than 50k miles - it is still a 93... and old = corrosion even with low miles, correct?

Alex,

Did you do any digging around the ECU or engine bay recently?

Corrosion is a separate concern. Mileage will not affect the function of the speedo board. The number of power cycles, the age of the electronic components, and exposure to heat-cold cycles have an impact on the speedo board. Chiefly, old electrolytic capacitors have a tendency to leak their fluid. It is a "silent" killer because one day it will work then the next day it will not.

The intermittent problem you are currently experiencing with your speedo, tach, and odo may also point to poor ground connections. Especially with an aftermarket ECU like the tried-and-true PowerFC. Just double check your ground wires. If a ground wire touches the chassis (which it should) then make sure it touches bare metal. Touching a ground cable to a painted surface will not conduct electricity, or do it very poorly. If the ground wire is connected to one of many OEM ground points then verify that a connection is made.

George,

I did some digging recently just to change ps belt and adjust tensioner. I was getting some squeaking in the belt and the inner rib was getting eaten off. The car has some aftermarket pulleys (Including under-drive pulley) and things were slightly unaligned which was causing the squeak - I added a couple washers behind the tensioner to bring it forward a bit and a new belt which eliminated that. Considering looking into stock set of pulleys down the road? Other than that, in the engine bay I just did full fluid flush (besides brake fluid) and suspension.

I just popped that papal off to show the ECU last night other than that no other digging there.

Speedo and Tach did start having more issues after all this work though - though the odometer has been having the issues.

Alex,

Thanks for the feedback. To keep the conversation on the topic of tachometer and speedo problems, you may need to verify that the ground cables are properly connected from the battery to chassis ground, and both the engine and ECU have ground cables connected to their respective (and proper) locations. The Wiring Diagram Manual (WDM) would help identify the location of each ground cable.

Other than the ECU being a PowerFC, what other mods were done to your FD? What engine mods, if any? How is the engine and ECU grounded? If the car was modified before your time then it would be important to identify any potential issues with ground wires.

Believe it or not, a poor connection to ground will cause all sorts of weird problems. It could even make you chase your tail!

George,

Thanks for the feedback brother!

I will be checking all grounds - as well as reference the WDM this weekend. Going to look up the WDM now. I plan to spend the weekend doing that and brakes.

Many various little bolt ons. FMIC, hard pipe, bov, down pipe, exhaust, fuel pump, pulleys, torque dampener, throttle body elbow (stock throttle body?)... Here is some pics of the engine bay.

https://cimg9.ibsrv.net/gimg/www.rx7...c916228b38.jpg

https://cimg4.ibsrv.net/gimg/www.rx7...db00581a95.jpg

https://cimg7.ibsrv.net/gimg/www.rx7...70c7e49614.jpg

https://cimg9.ibsrv.net/gimg/www.rx7...5d122a4f31.jpg

https://cimg1.ibsrv.net/gimg/www.rx7...6804c74dfb.jpg
I was finagling with the torque dampener last night because it was rattling bad on the brake lines, but I don’t think that had anything to do with it.

Hopefully get some time to spend cleaning up the bay too a bit. It was sitting for a while.

-Alex

I noticed it looks like the OEM ground on the firewall slightly towards the passengers side of the car has been redone. I may be wrong on this one, but I remember reading somewhere that can effect the gauge cluster functionality, worth looking into to make sure that ground hasn't worked its way loose.

Good eye:bigeyes:

Just checked it - that monkey is on there tight as can be though

I am really going to have to go through all of it this weekend. Wow, man I did not mean to send those pictures so big. Lol. I did it off my phone and am on my computer now.. Sorry about that

-Alex

@SwappedNA, you beat me to the punch! I noted the same as I looked at the photos.

@YahmiPower, In this instance, the larger photos proved to spot that potential ground cable issue. The cable may be tight to the firewall but does it make metal-to-metal contact and not metal-to-paint?

After studying the WDM and component locations, Ground Point #3, which is located on the right side of the engine bay, is a ground that directly ties into the instrument cluster and speedo board. There are other ground points to the instrument cluster such as Ground Points #1 and #6 but these are associated with the signal and brake indicators, in addition to the warning lights on the instrument cluster. Check it on on Pgs Z-42 thru Z-44, Diagram C-1a and C-1b in the WDM.

I was about to say the same thing about the larger photos. There was probably no chance I would have seen that ground cable otherwise. Could possibly be a loose ground, I'd check those mentioned in the wiring diagrams.

George,

Okay Roger that --- I feel that this may be the issue since it was intermittent and progressively getting worse --- I am learning a lot --- first timer - so I really appreciate all the help!!!:nod:

This is the WDM I am referencing. Ground Point #3 is connected there to the passenger side firewall, and to the back of the intake manifold if I'm not mistaken.
http://wright-here.net/files/manuals...ng_Diagram.pdf

I will definitely check this ASAP after work today

-Alex

Just got home from work

switched that ground wire to touch straight to the frame (see pics below) real quick before I cook dinner to see if it would be the quick fix - no luck.

The ground on the back of the throttle body seems like a solid connection. Is it possible they’re just old and kind of crudded up from the elements and need replacing?

I’m going to have to save full inspect of ground wires ecu etc for this weekend when I’m doing brakes. Just an update for now. Will try and pull circuit board this weekend too if need be - even if just to inspect and wipe down with alcohol

I’m On my phone - here’s some big pictures again guys.

Before...
https://cimg6.ibsrv.net/gimg/www.rx7...0ac5fdd0a.jpeg
https://cimg7.ibsrv.net/gimg/www.rx7...3f5f15f8e.jpeg

After
https://cimg9.ibsrv.net/gimg/www.rx7...bbd50c877.jpeg
removed this bracket too because it didn’t appear to be doing anything.

-Alex

That bracket you removed is where the factory ground would connect, if you look at the far right of the bracket in the picture of you holding it, you can see the spade looking connector that shows signs of having something connected to it in the past, that would be the factory ground connector for it

So it is unnecessary though correct?

Because it appeared to not be doing anything

Alex,

You can re-install the interface plate. The interface plate, ground cable flats, and the mounting bolt make a better connection connection to ground. Based upon the photos you just attached, I would say that the ground wire between the engine and firewall looks good. You could test the cable to make sure it does not have any breaks but I doubt that is your overall problem.

If you wish to test that ground cable, then you will need a second set of hands. Remove the cable from the firewall and engine block. Connect a DMM to each side of the cable and measure for resistance. It should read a dead short (0 ohms or anything less than 1 ohm). Have an assistant wiggle the cable around (up-down, lef-right,... you get the idea) while you read the resistance. It should not move/vary much.

That process I described is a quick test for any breaks/kinks along the length of cable. It is important to mention: do not kink the cable as you wiggle it around. Should you see a wild swing in resistance, for example from 0 ohms to "OL" or you see a reading that jumps up to 10,000 ohms, then the cable has kinks and needs to be replaced.

Does that help?

George,

Roger that. Makes sense. Will be doing this tomorrow and updating tomorrow!

-Alex

Hi all,

I sent my cluster off for repairs and found leaking capacitors which have been fixed but i'm still experiencing the same problem. Both RPM & Speedi still not working...

Both went out at the same time which made me think it was for the cluster...

Any help is appreciated.

@rexhvn,

That's a bummer that the problem was not fixed. I have several questions for you:

1. What did the company that performed the repair replace?
2. Were they able to test the cluster before it was returned?
3. Have you contacted them to say the problem has not been fixed?
4. When you got the cluster back, did you take any photos and/or inspect it? Especially, any photos of the speedo board?
5. What ECU are you using?
6. Have you done any other troubleshooting or taken any measurements?

@Gen2n3

1. What did the company that performed the repair replace?
The feedback I received was a number of leaking capacitors were replaced.

2. Were they able to test the cluster before it was returned?
The company said it was tested on their end and found no further issues.

3. Have you contacted them to say the problem has not been fixed?
Sure have. They've requested certain photos and said the issue may be on the back of the cluster or the speed sensor.

4. When you got the cluster back, did you take any photos and/or inspect it? Especially, any photos of the speedo board?
I've taken out the board and can see new capacitors

5. What ECU are you using?
PFC - Revs etc are working fine on the PFC

6. Have you done any other troubleshooting or taken any measurements?
At this stage using feedback from the forum & research which pointed to the cluster itself.

rexhvn,

Thanks for answering my questions. It is good to hear that you can see revs on the PFC. I have a few more for you:

1. Did your speedo & tach work after installing the PFC?
2. How long has your tach & speedo been broken?
3. Do you have photos to share of the speedo board and cluster?
4. Do you have a copy of the Wiring Diagram Manual (WDM)? Do you have any problems with reading schematics?
5. In your original post, you said there were some wires that you messed with. Do you know what they are?
6. Does the odometer work or is it blanked out? Did it work before or after the repair?
7. Did you try my recommendations from Post #9; what was the outcome?
8. Are you prepared to do some wire troubleshooting - measuring resistance, etc.?

I re-read your initial post. If you tried a 2nd cluster and got the same result of no tach or speedo then it looks more like a wire issue. Please do your best to provide details and I bet we can find the cause of your problem. If you've taken pictures along the way then please share them too.

This is what I understand thus far:
1. PFC measures tachometer RPM without issue.
2. The tach and speedo stopped working after the cluster was removed and wires were "fiddled with."
3. A second cluster was installed to verify the problem. The problem remained the same with the 2nd cluster.
4. The primary cluster was sent out for repair and defective capacitors were replaced.
5. All other gauges and warning lights on the cluster (fuel, oil press, water temp) work.

Is there anything else that I may have overlooked?

Thanks, i've added some comments.

rexhvn,

Again, thanks for the cluster photos and your answers. You gave a good clue. When you fiddled with the wires, the speedo and tach came back to life but soon died. To me, that indicates a problem in your wiring.

Let's take a look at your connectors on the wire harness. Please take photos of each of the 4 C1-01 connector that attach to the cluster and then post. Get as close as you can with these photos. The photo should include the connector and roughly 1 inch of wire. You want to keep the camera close to the connector. No distant shots, please.

If you haven't done so already, bend out each of the tabs on the flex print. I briefly described it in Post #9. Remember, do not kink the flex print! This link gives a good example of how much curl the flex print tabs should have: Instrument Cluster Flex Print Components BTW, keep that link handy as we may refer to it frequently. Once completed, please post photos.

Would you also remove the black access cover over CON1 and take a photo of the flex print connected to the speedo board? I would like to see how it is connected to the speedo. We need to verify its shape, curl, and condition.

The primary diagram we will reference will be Diagrams C-1a and C-1b from the WDM. Before we start reading wires, I'd like for you to try the above recommendations and then post photos. Much like going to the doctor, we are going to rule out a few things in a (hopefully) logical manner.

Gen2n3, thanks for your all your help thus far.

I did what you recommended in post 9, cleaned the tabs and gently bent the tabs. The connectors are definitely making contact. All the pins within the connectors seem to be secure as well but unfortunately no change. Perhaps something has been shorted.

In terms of providing the pictures of the connectors, did you want these front on or from behind? Plugged in or not plugged in?

Thanks

Did you use Circuit board medics like I mentioned? My biggest complaint with my situation was I suspect they just tried replacing capacitors without diagnosing the issue, and when the caps didn't fix it, they ended up having to actually troubleshoot it and it took longer than they advertised. They did good work in the end, but they missed it the first go around.

Reason I mention it is because my cluster did the same thing, they replaced the caps, it still didn't work on the tach/speedo/odo. They finally found out that it was a bad trace on the board. Probably not your issue, but just best to be aware of it in case I guess.

I'm interested in seeing how this turns out.

rexhvn,

Good to hear that you cleaned the flex print contacts and re-shaped them. I wasn't expecting that to fix your current problem. We'll get to the root cause of the problem, so hang tight.

When taking the photos of the C1-01 connectors, leave them disconnected from the cluster. I would like to see each connector at different angles. Basically, a pic for each row of pins on the connector. As a reminder, I only need to see about 1 inch of wire above each connector.

In between posting photos, please get a DMM (digital multimeter) ready. Do you already have one? If not, Harbor Freight sells a basic (and cheap) one for around $10. We will use the DMM to test wires very shortly. Have you used one before? How much electrical or electronics training do you have?

SwappedNA,

Thanks for sharing your experience with circuit board medics. I suspect the problem may be in the wiring harness and not the cluster. He swapped in a different cluster (of unknown condition) and got the same indication. If the problem did not change then that may indicate the problem is outside of the cluster.

Thanks Gen2n3.

I've got a DMM but i'm no specialist by any means so any help is appreciated.

Below are images of the C1 connectors. Let me know if these suffice.


https://cimg5.ibsrv.net/gimg/www.rx7...e6aebf62c3.jpg
https://cimg6.ibsrv.net/gimg/www.rx7...99c67f959d.jpg
https://cimg7.ibsrv.net/gimg/www.rx7...dbc68c907b.jpg
https://cimg8.ibsrv.net/gimg/www.rx7...90d1c56f69.jpg
https://cimg9.ibsrv.net/gimg/www.rx7...032f90b96c.jpg
https://cimg2.ibsrv.net/gimg/www.rx7...5d8afdffc4.jpg
https://cimg5.ibsrv.net/gimg/www.rx7...3ed4d783f0.jpg
https://cimg6.ibsrv.net/gimg/www.rx7...3fed5c71d0.jpg
https://cimg7.ibsrv.net/gimg/www.rx7...329803e475.jpg
https://cimg9.ibsrv.net/gimg/www.rx7...65c268d6c8.jpg


https://cimg0.ibsrv.net/gimg/www.rx7...67f9f85679.jpg
https://cimg1.ibsrv.net/gimg/www.rx7...c087fe5815.jpg

rexhvn,

Thank you for posting the photos of your C1-01 connectors. After reviewing them, I didn't see anything unusual. So the next step we are going to take is to measure wire resistance to the cluster. We will also take measurements on the flex print. Additionally, we will measure battery and Ignition (switched) battery voltages at key connectors. The voltage measurements will be the last part of our measurements because of two things: we want to ensure that the wire can deliver a signal and we want to verify that signal isn't being diverted (shorted) elsewhere.

In preparation to take measurements, you are going to need a DMM, the WDM Diagram C-1a, and this hand-drawn schematic that I made for the flex print: Post 17 - Flex Print Schematic. Since you are unfamiliar with measuring resistance and voltages, I have some basic recommendations:

1. Always measure resistance in an electrical circuit with the power off or disconnected!
2. The DMM has 2 leads. A red and black lead. The red lead is known as the positive side and the black lead is known as the negative side. When measuring electrical resistance, voltage, or amperage, it is VERY important to observe the proper connection (observe the polarity) of the test lead to the electrical circuit.
2.a. The assumption to make is: always connect the black lead of the DMM to the negative side and the red lead of the DMM to the positive side of the circuit. There are exceptions, but that will be handled on a case by case basis.
2.b. For example, if you measure the car's battery, it will measure 12v (+12v) with the black lead on the negative terminal and the red lead on the positive terminal. If you connect the black lead to the positive battery terminal and the red lead to the negative battery terminal then the result will be -12v.
3. Resistance is measured in ohms and is represented by the Greek letter omega, Ω.
4. When measuring resistance in a wire, it is either a short (good indication) or an open (bad indication). Anything under 1 ohm is a short, which is a good indication. Typically, the DMM will indicate a value less than 1, like 0.3. Conversely, an open is represented with "OL" (Overload, or out of range) or a "1 . " (that is a 1 with a lot of blank space). The "open" display depends upon the manufacturer of the DMM. An open means the DMM sees an infinite amount of resistance.
4.a. If you see a measurement of 5,000 ohms (5k ohms) or anything in between a short and an open then that indicates something else is connected in the circuit.
5. In a circuit, connect the black lead to chassis ground or a known ground! Typically, ground is ground so it doesn't matter where you place the lead. However, we will target specific grounds on the instrument cluster because they go to different places.
6. When measuring resistance in wires, polarity is not important.

We are going to look at the flex print first. So get that hand-drawn schematic ready!

You will need to remove the black cover to the speedo and remove the flat flex print connector from it. You will also need to reference Post #16 (from the link provided above) for specific pin locations and labels. Remember, this is with the cluster removed from the car. Here are the 1st set of checks:

1. Measure resistance between CON1 Pin 1 and and Flex Print Connector C1-01 Pin 4E. It should measure a short (0 ohms). This is Battery signal (+12v) line.
2. Measure resistance between CON1 Pin 15 and Flex Print Connector C1-01 Pin 2D. It should measure a short. This is Ignition (Switched) +12v signal line.
3. Measure resistance between CON1 Pin 14 and Tach GND terminal on the flex print. It should measure a short. This is the ground signal line to the tachometer and other ground.
4. Measure resistance between CON1 Pin 14 and Flex Print Connector C1-01 Pin 1E. It should measure a short. This is the Ground (GND) signal line.
4. Measure resistance between CON1 Pin 14 and Flex Print Connector C1-01 Pin 4K. It should measure OPEN. This is a Ground signal but it is used in a different place.
5. Measure resistance between CON1 Pin 12 and Tach Signal screw terminal on the flex print. It should measure a short. This is the tachometer signal that drives the needle.
6. Measure resistance between CON1 Pin 11 and Tach +12v screw terminal on the flex print. It should measure a short. This is the +12v power used for the tachometer.
7. Measure resistance between CON1 Pin 1 and the other pins (Pins 2 thru 15) on CON1. Each pin should measure OPEN.
7.a. This step ensures there are no parallel paths to ground for any signal going to/from CON1.

NOTE: No test involving power will be made to the cluster.

Please report back on your findings. Afterwards, we will move to the next step, which is testing the car's wire harness from the C1-01 to other points. Be prepared to disconnect the ECU connectors. Would you also take a photo of CON1, both the flex print side and speedo side?

George,
Hey I've been lurking soaking up the advice you've been giving here on this thread as I am having similar issues. I feel like my situation is the same as Rexhvn and I followed your T/S steps you posted above. Assuming his tests all came out good, as mine have, what's his/my next step?
Regards,
Rod