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Double check your ground points to and from the speedo, instrument cluster, and Power FC. Make sure your Power FC is properly grounded! Do you have any photos of the speedo board after you replaced the components? There could still be an underlying issue with it.
Ill double check ground points but the car does work just fine with a 99 spec cluster that was in it before as well as a white faced mazdaspeed cluster. I also swapped the mazdaspeed speedo board into the 93 cluster housing and it worked fine. So the issue is on the 93 speedo board itself. Pictures are before I touched up a few more points. (IC2 and the middle diode below it)
I see alot of suspect areas on your board. Most caused from prolonged exposure to a soldering iron. Could you please post pics of the areas you touched up? These before photos help but lacks the current state of the board. I can also tell the LCD screen needs to have its polarized film replaced. That crazing and discoloration spot will give the effect of a blank screen. Furthermore, I noticed some capacitors that need to be replaced, such as C4 and C6. More photos will help reveal more problems that should be addressed.
Alright so an update. Swapped the gauge face and stepper motor to my known good board and it does the same thing. So looks like the stepper motor is the issue on this somehow. Guess im on the hunt for a used but good stepper motor. All the nastiness on that board was just uncleaned flux
I pulled the gauge face off the stepper motor and noticed 1 of the 4 coil wires was disconnected from the pin soldered it back on and moved back to the old board only to find it no longer wants to show odometer, tac or speedo signal. Odometer and Tac had no issues before. I see no reason why it would just stop working going to inspect everything tomorrow. Used a 0.015uF 50V cap on C15
Update: FIGURED IT OUT!!! and have a working cluster now. One of the wires for the coils in the stepper motor had broken off the pin. Unsure if this is from me disassembling and reassembling multiple times or it was like that. Had enough length remaining to just solder it back to the pin and have a fully functional cluster now. Thank you so much for the help.
Thanks for the update. I am happy to hear that your speedo is fixed! Would you have any additional photos to share of the broken wire? That problem sounds very rare.
This is the before picture. Forgot to take an after picture but just unwound the wire slightly to get a little bit of slack in it and soldered in to the post.
I need some help with my 93 instrument cluster. Spent the last few years converting this car from street to track working first with Chip Motorsport (loser) and getting nowhere to a car that runs with Chris at Banzai (winner). To make a very long story short the speedometer works but the odometer does not and the tachometer is dead. All other gauges seem to work. So I pulled the cluster from the dash and shipped it off to Atlanta Speedometer for a completer rebuild-got it back last week, re-installed, started her up and everything seemed fine. left the car running to warm up and 10 minutes later when I came back to the car the Tach is now dead flat but blipping to idle rpm every few seconds. I called Atlanta and they tell me the cluster works fine on the bench so I must have a signal problem or something. Can anyone give me some ideas of where to look or how to investigate issues for this Tachometer? Thanks, JD
What ECU are you using? You will need to verify the signals between the ECU and speedo. Do you have the wiring diagram manual (WDM)? You'd want to use Diagram C-1a and B-1b. Furthermore, you need to ensure the vehicle is properly grounded. The speedo & instrument cluster require a specific ground! It is the ground on the engine block at Ground Point #3 (refer to diagram C-1a).
Since you had the cluster repaired at a shop, it may also not hurt to examine the speedo board in case something was overlooked. Since there would be some warranty to accompany their repair, I do not recommend removing the speedo face from the speedo board. However, you can remove both speedo and tach boards from the cluster to examine it closer. You can post pictures of the boards here and I could offer some advice, if needed. Just remember to get some close-ups of the board at various points.
George, as I was looking through the various posts on the tachometer issue i see that you seem to be the "guru" on this topic. So, I am not a mechanic in any sense of the word as far as mechanical operation goes. I can do basic things like remove an instrument cluster, but you folks really get technical and I dont know what you are talking about. Is the ECU "Apexi"? I do not have a wiring diagram or repair manual-I will see if i can locate something. Let me check into the grounding issue and start there to see if I can make headway. Are you able to send me a photo of that ground location?
Yes, thanks for the compliment! I am well versed in the tach & speedo problem.
You will need the following manuals if you plan to work on your FD:
FSM - Factory Service Manual
WDM -Wiring Diagram Manual
BEM - Body Electrical Troubleshooting Manual
The ground point is illustrated in the WDM, as indicated above.
You will also need a digital multimeter (DMM) to measure various electrical signals - voltage, resistance, and current. You will mostly use the voltage and resistance settings on a DMM. You can pick up a cheap one at Harbor Freight.
The ECU is the Engine Control Unit. It is also called the Powertrain Control Module-Engine (PCME). Knowing what ECU you have installed will help a lot! The Apexi unit you mentioned is an aftermarket manufacturer of ECUs and is a popular ECU replacement from a stock ECU. Are you using a PowerFC? You may need to reach out to Chris @ Banzai for some help in determining which ECU you have and how it is connected to the wiring harness. Typically, an aftermarket ECU requires a wiring adapter. For example, the Apexi PowerFC requires certain pins to be "pulled" from the wiring harness because certain features need to be disabled in USDM spec cars.
The big question to ask yourself is: do you plan to do the work yourself and find what's wrong? You will be removing components and measuring wires. Measuring wires is a relatively easy task but can be overwhelming for the uninitiated. The most important thing to remember is that troubleshooting an electrical problem takes time and patience.
As I understand, an improperly grounded PowerFC will cause tach problems for example, the speedo needle following the tach.
Did your instrument cluster work before modifying it for track use? You may also ask Banzi for any pointers in ECU and instrument cluster problems. I really don't have much experience with the aftermarket ECUs. I mostly deal in the factory setup because that is a known value and is easily referenced in the manuals. You will need to know which signals your ECU is sending and receiving so it can be translated into the WDM.
George, thanks for the information. I am not sure that I am up for the challenge that you describe, but, I am still doing some discovery to determine what I can. To be honest I do not know if the cluster was fully operational when we began the rebuild on this car. knowing what I know now I am not sure this rebuild would have ever been started. So, let me see what i discover once i have gotten a hold of the manuals and what might be involved for me to chase this problem down. Again, thank you for your help.
Check out this thread that covered a repair to the speedometer. That member had some experience behind a soldering iron but he was hesitant to tear into his speedo board. There is a wealth of info in this thread too!
George, regarding the tach and instrument cluster repair I contacted Atlanta Speedometer to talk about their repair to my instrument cluster. First, I do not know if when I pulled the cluster out of the car if in fact there was a problem with it (the cluster) or a lack of or weak "signal". They report that they still go through the cluster and check everything out but the question is, "do they"? I talked to a tech there who says my problem is most likely a weak signal that can be diagnosed through the F-3 pin with an oscilloscope! he's kidding right-I had to spell check to even spell oscilloscope! He also stated that just cause I had it fixed, something else could have broken on re-install and power up. In other words-go sit on a stick! Do I take the cluster back out and re-send back to Atlanta for another check up or do I begin to tear this thin apart per your tutorial?
On another note, I sent you a PM regarding some forum advice. Thanks much, JD
Last edited by Gen2n3; 12-31-20 at 12:11 PM.
Reason: Cleaned up personal info.
Either way, it sounds like the instrument cluster will need to be removed. Whether you repair it or send it to a repair shop will be up to you.
Yes, an oscilloscope (o'scope) is a piece of electrical test equipment that enables you to slow down an electrical signal to visualize it. For example, the 115 VAC power that comes from your electrical outlets will have 115 volts and a 60 Hertz cycle. When viewed on an o'scope, you would see a clean sine wave with a peak-peak voltage of 115 volts and one full alternation (often called the period) of 1/60 second, or roughly 16.7 msec (milliseconds).
Since you need to remove the cluster, it would be a good idea to examine the speedo board. Take pictures, as noted in several examples in this thread. Post them here and I could advise on its condition. At this time, do not remove (de-solder) the speedo face from the rest of the board. When taking photos of the board with the face still on, you may want to shine a flashlight in certain areas to counter any shadows.
While the cluster is removed, that will allow you to take resistance and voltage measurements. The WDM and BEM manuals will be needed to troubleshoot this problem. You will also need to get the wiring diagram of the ECU and any interconnecting adapter between the ECU and vehicle wire harness. What ECU are you using, again?
You will need to diagnose the problem with the tach. Since you had a specialist work on the cluster and they claim it is good then we need to further examine things. I can advise you but that means you need to be rapidly acquainted with the car's electrical systems and schematics. It may sound like a big problem but you should be able to handle it. You will need plenty of patience and time to solve this problem. It will not be a simple fix.
Besides common hand tools, you will need a DMM. I mentioned it above and it is required anytime you have to read wire measurements.
When you remove the cluster from the gauge hood, post a photo of the cluster back side. I want to see how the flex print sits inside each connector socket.
George, I got a hold of the 93 Mazda "workshop manual" and it seems fairly complete for the wiring diagram. I did not see where it walks you through remove and disassembly of the instrument cluster, but, that is on my list of things to do today. So, the exercise begins-I will pull the cluster and send you some photos of what is going on. Do you recommend I just follow one of your previous walkthroughs from above or you will direct me for procedure? I also picked up a meter, but I am not clear on how to use it-I will figure that out. Stay tuned.
The 2 settings you will use the most will be resistance/continuity and direct current (DC) voltage. What meter did you get? You may post a pic, if you'd like.
In previous posts/associated threads, I helped out other members with their meter setups and measurements. Please refer to them for guidance that is particular to the FD wiring diagrams. Look for advice on using the car's chassis ground as a method of measuring wires between 2 connectors that are far apart. For example, one can measure a wire that runs the length of the car from just the engine bay. Trust me, using chassis ground to measure wires saves time and resources!
Regarding instrument cluster removal, refer to the "just got done figuring out how to fix an FD odometer" thread. The link to it is in Post #1 of this thread and scattered elsewhere here. It should amplify the cluster removal instructions in addition to opening up the cluster to extract the speedo.
Which manuals did you get - the FSM, WDM, and BEM? I ask because these are separate manuals that can be downloaded and will need to be referenced during your troubleshooting phase.
If I didn't express it previously, print the wiring diagram for the instrument cluster, Diagram C-1a and C-1b. You do not need to print the parts location diagram that is associated with each diagram. Just print the schematics. I also recommend using color pencils/crayons/markers to mark the circuit you need to measure. Something like red for checks bad, green for checks good, and a few other colors to identify different wires, such as Coolant Level Sensor, Cruise Control, ECU input, etc. Use a pencil to record a measurement for each wire on the schematic. You may have to re-measure certain wires as new information becomes available so it is a good idea to document initial measurements and follow-on measurements.
Most of the measurements you will take will be for resistance. Therefore, no power will be applied to the car. You may disconnect the battery as a precaution but more often than not, the car can be left in the OFF position without a key inserted in the ignition cylinder.
"Which manuals did you get - the FSM, WDM, and BEM? I ask because these are separate manuals that can be downloaded and will need to be referenced during your troubleshooting phase."
Looks like the manual l have is a copy of a Mazda generated, but I cannot find any info as to who wrote it, etc. Tell me where to get the manuals you are referencing above.
Don't remove the speedo face just yet. You had that board repaired recently and should still be under their warranty. For now, take pics of the front side of the board. Get close-up shots and shine a flashlight in the darker areas.
What are those wires connected to the tach screws? Do you know where they go? Do you know who put them there? You may need to remove those wires. Leave them be for now...they could be used by your aftermarket ECU. From a historical point, seeing those wires connected to the tach screws is a shortcut to get the tach working. The downside to that approach is it could damage the speedo/tach circuit in the long run. Additionally it is an extra failure point that can short out.
The back side of the board looks ok, I can tell that components were replaced.
Do a google search for RX-7 factory service manual. You should see a link to download all 3 manual types. I believe there are a few links in the forum FAQ that will also net the same result.
You went old school on a multimeter. The analog dial takes me back. The important thing to note when using an analog meter is to zero the needle before taking resistance measurements. The step is simple - set the meter switch to measure the resistance (ohms) then touch the two probes together. The needle will deflect to the right. Use the red thumbwheel to adjust the needle on 0 ohms (green scale line).
Additionally, the most accurate readings on an analog multimeter are taken in the center of the display. You ALWAYS work from the highest setting then down to a lower setting until the needle deflection is in the center (80% of the field). Your multimeter has x1k and X10k (can't see the last - maybe x200k?). That is a multiplier that you must factor when measuring resistance.
For example, you measure resistance with a mid-scale deflection on 50 ohms. With the switch set to x10k, you need to multiply that value by 10,000. Therefore, the measurement would actually be 50 k-ohms (50 kilo-ohms or 50,000 ohms).
By default, resistance is infinite or "open" when the meter leads do not contact anything. When looking at the scale, the infinite (infinity symbol) for resistance is in the same spot as 0 volts or 0 Amps.
"What are those wires connected to the tach screws? Do you know where they go? Do you know who put them there? You may need to remove those wires. Leave them be for now...they could be used by your aftermarket ECU. From a historical point, seeing those wires connected to the tach screws is a shortcut to get the tach working. The downside to that approach is it could damage the speedo/tach circuit in the long run. Additionally it is an extra failure point that can short out."
On the Driver side post there are 2 gauges mounted: Boost & Temp. I believe that the two wires on the back of my cluster go to the boost gauge installed by Chris from Banzai.
I was going to ask you if I shouldn't be chasing down connections looking for a short before tearing the cluster apart. Let me know if there is a previous forum post to follow for chasing down my connections?
11-26-20, 03:38 PM
