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Hi,
I replaced the standard 1000 micF and 10micF due to no display at all, cleaned board, soldered the tops, etc. i cant find any visual issues. it works now, but shows Zero miles. any ideas? results do not change if i solder the speedo back in.
Good to hear that you successfully replaced C3. However, the odometer reset is a problem that I cannot answer, yet. What does the rest of your speedo board look like? Could you post pics of your board in segments? Pay attention to the other capacitors and IC3.
More than likely, the odometer is permanently reset.
I see this was your first post since becoming a member in 2015. Where have you been? Just lurking?
Good to hear that you successfully replaced C3. However, the odometer reset is a problem that I cannot answer, yet. What does the rest of your speedo board look like? Could you post pics of your board in segments? Pay attention to the other capacitors and IC3.
More than likely, the odometer is permanently reset.
I see this was your first post since becoming a member in 2015. Where have you been? Just lurking?
thanks for the response. unused to have an FD, just recently got a 93 BB base that had this odometer issue.
I replaced 5 caps and ohmed the traces to and from them to make sure they were making connection. most of the ones I changed the negative side goes to main ground. acid did damage one trace south of c3 so it's repaired with a wire. I've used a high power light to try and find any more broken traces.
when battery is disconnected and reconnected the LCD does a calibration dance then says zero miles. my next stop is to check power on ic3 and tr5 when powered up.
What does the rest of the board look like? How do the legs look on all of the transistors that were damaged by leaked electrolyte? See the examples from others who posted here for an idea on what to look at.
How bad was the damage from the leaked electrolyte? How does the back of the board look?
Did you verify the broken traces with a DMM continuity check? Sometimes, a trace may look broken when looking though the solder mask. It is always advisable to verify with a continuity check.
Last edited by Gen2n3; 05-15-20 at 09:56 PM.
Reason: Added DMM check question.
What does the rest of the board look like? How do the legs look on all of the transistors that were damaged by leaked electrolyte? See the examples from others who posted here for an idea on what to look at.
How bad was the damage from the leaked electrolyte? How does the back of the board look?
Did you verify the broken traces with a DMM continuity check? Sometimes, a trace may look broken when looking though the solder mask. It is always advisable to verify with a continuity check.
thanks they really great cars.
I have spent a few hours continuity checking traces. everyone I've done are fine. all the new caps I installed I verified the conntinuity to neighboring components. the transistor legs look good none broken and I've cleaned off any corrosion. it wasn't bad to begin with. the leaked electrolyte just seemed to have damaged that one race I just repaired. it didn't have continuity so I added the wire.
tr5 is sending 5v to ic3 and ic4, both ics have ground. I've continuity tested the ic3 branches. so my mileage chip is powered on and it has ground so it should be sending signals.
my test tomorrow is to put the rear up on the car and drive a mile. then power cycle by unplugging battery to see if it saves the value. if it does I guess I have a new car.
actually that sucks because I'll have to report it as a odometer replacement. I'll report back after that test.
I do remember reading on the other main thread about the display fix that someone else saw zero miles I'll have to pm them.
As I recall, the other member lived with the odo reset. Have you found anything else on your problem speedo board? Do you have a lot of experience in electronics?
Did you replace the capacitors on your speedometer yet? I look forward to hearing about your progress.
All capacitors are arrived, I didn't had time to work on it.
I hope to do this on Tuesday.
Off course I will tell You immediately when done
Thanks for asking
As I recall, the other member lived with the odo reset. Have you found anything else on your problem speedo board? Do you have a lot of experience in electronics?
i think living with it is my only option. i drove around a bit and racked it up to about 5 miles. unplugged battery, and plugged it back in. mileage is still 5. Trip odo works fine and resets fine.
im going to make a few calls to some odo companies tomorrow to see if they can input a mileage estimate and whats even involved with that, or just report it as a new odometer when i get it inspected next.
Im an electical engineer by profession, but its been a decade since ive done manual labor on circuit boards. this is just a two layer board, so its pretty easy except the high density ICs. unfortunately i dont have wiring diagrams and to test many of the components you need to remove them. i replaced all the larger caps and cleaned the board really well. i think that is all the board needed.
Im throwing in the towel in terms of trying to get the mileage back, my cluster works flawlessly, other than the reset mileage. i consider the repair a success, however i am disappointed i wasnt able to recover the original mileage. luckily the car isnt a 5k mile time capsul, it had roughly 115k on the clock, so its a driver anyway.
Either way i just want it documented for when/if i ever sell the car.
As I recall, the other member lived with the odo reset. Have you found anything else on your problem speedo board? Do you have a lot of experience in electronics?
Dear George,
I replaced all the capacitors except 1 the C9. I have a doubt; where go the negative side? is not marked on the board.
C9 is a bipolar capacitor. It does not have a positive and negative side like the others. You can install it either way without any issues. I can't wait to hear about your progress!
i think living with it is my only option. i drove around a bit and racked it up to about 5 miles. unplugged battery, and plugged it back in. mileage is still 5. Trip odo works fine and resets fine.
im going to make a few calls to some odo companies tomorrow to see if they can input a mileage estimate and whats even involved with that, or just report it as a new odometer when i get it inspected next.
Im an electical engineer by profession, but its been a decade since ive done manual labor on circuit boards. this is just a two layer board, so its pretty easy except the high density ICs. unfortunately i dont have wiring diagrams and to test many of the components you need to remove them. i replaced all the larger caps and cleaned the board really well. i think that is all the board needed.
Im throwing in the towel in terms of trying to get the mileage back, my cluster works flawlessly, other than the reset mileage. i consider the repair a success, however i am disappointed i wasnt able to recover the original mileage. luckily the car isnt a 5k mile time capsul, it had roughly 115k on the clock, so its a driver anyway.
Either way i just want it documented for when/if i ever sell the car.
I'd send it to DNA Speedometers in FL to diagnose and fix. They can also adjust the odometer reading to reflect your mileage - or close to it.
i think living with it is my only option. i drove around a bit and racked it up to about 5 miles. unplugged battery, and plugged it back in. mileage is still 5. Trip odo works fine and resets fine.
im going to make a few calls to some odo companies tomorrow to see if they can input a mileage estimate and whats even involved with that, or just report it as a new odometer when i get it inspected next.
Im an electical engineer by profession, but its been a decade since ive done manual labor on circuit boards. this is just a two layer board, so its pretty easy except the high density ICs. unfortunately i dont have wiring diagrams and to test many of the components you need to remove them. i replaced all the larger caps and cleaned the board really well. i think that is all the board needed.
Im throwing in the towel in terms of trying to get the mileage back, my cluster works flawlessly, other than the reset mileage. i consider the repair a success, however i am disappointed i wasnt able to recover the original mileage. luckily the car isnt a 5k mile time capsul, it had roughly 115k on the clock, so its a driver anyway.
Either way i just want it documented for when/if i ever sell the car.
i can program the mileage back on your cluster. PM me if ya like.
running into a bizzare issue. 93 with pfc, and now adaptronic
for several years tach would read normal, half the time, then on long drives, or just random days it will jump about 1K too high at 3000, less inaccurate at idle, worse at very high rpm.
may jump off then after a few minutes go back to normal. or just do it for several seconds.
same issue is occurring after having cluster repaired. and with a spare cluster.
leading me to suspect this issue is not in the cluster it self.
That is an interesting problem you are experiencing. I read your PM as well so I'll post my observations here instead of replying to both.
When you sent the tach off for repair was it just the tachometer or the whole cluster? Do you know exactly what was done to repair the cluster? How long ago was it repaired?
The tachometer signals are actually processed by the speedo board. One key signal actually originates from the ECU. Since you are running an aftermarket ECU, the important question to ask is: Does the aftermarket ECU send a tachometer signal to the speedo board? Based upon your description, it sounds like it does.
The next thing is to evaluate the speedo board. Currently, time is the enemy of a speedo board. The electrolytic capacitors will leak. If it is not identified correctly, the leaked electrolyte (acid) will eat away at the other components and run down the board. The speedo board sits in a vertical position and therefore any fluid released from a capacitor will ooze down the board. Dependent upon the time of repair, capacitors that may have looked good or tested good could have failed since then.
Another issue with a bouncing tachometer is the IC1 chip that is soldered to the circuit board on the tach itself. Over time, these solder joints will fail and cause the chip to randomly malfunction. The fix is easy: re-solder the IC chip. You don't have to remove the old solder then replace it with new stuff. Just re-flow each joint and it should be good to go.
Please remember, diagnosing a tach or speedo problem is a very unique beast. Which is why this thread (and others) are here. The first and important step to recommend is a visual inspection of your tachometer and speedometer boards. That would possibly show any damage or defective components. Furthermore, it is equally important to understand how an aftermarket ECU (PFC or otherwise) sends a tach signal to the speedo board.
Hypothetically, if you swap in a different instrument cluster and you are still seeing problems then it could be one of 2 things:
1. Poor/loose ground to the instrument cluster and/or ECU
2. ECU is not sending the tach signal to the right place or it is intermittent.
Ultimately, I recommend removing the instrument cluster and visually inspect both circuit boards. You may post pics in this thread and I could offer advise when needed.
C9 is a bipolar capacitor. It does not have a positive and negative side like the others. You can install it either way without any issues. I can't wait to hear about your progress!
George, Thank You very much for all Your precious support.
My speedometer is working very well.
I found that the Tachometer needle were moving strange (spiking is correct?), i solved cleaning well the 3 screw on the back. I cleaned without using abrasive material, so I didn't removed the zinc coating.
That is good news to hear! Congratulations! I only advised. You did all the hard work. If your tach bounces again then you may need to re-solder IC1 on the small tachometer board. One other observation - make sure the flex print tabs are curled out on the instrument cluster. The curl would help make contact with the hard plastic connectors from the dash wire harness. Please, do not crease or kink those tabs because it will break the flat copper trace inside.
We can have a beer (no Corona, hahaha!), whiskey, vino, or aperitivo after the world calms down from COVID-19.
That is an interesting problem you are experiencing. I read your PM as well so I'll post my observations here instead of replying to both.
When you sent the tach off for repair was it just the tachometer or the whole cluster? Do you know exactly what was done to repair the cluster? How long ago was it repaired?
The tachometer signals are actually processed by the speedo board. One key signal actually originates from the ECU. Since you are running an aftermarket ECU, the important question to ask is: Does the aftermarket ECU send a tachometer signal to the speedo board? Based upon your description, it sounds like it does.
The next thing is to evaluate the speedo board. Currently, time is the enemy of a speedo board. The electrolytic capacitors will leak. If it is not identified correctly, the leaked electrolyte (acid) will eat away at the other components and run down the board. The speedo board sits in a vertical position and therefore any fluid released from a capacitor will ooze down the board. Dependent upon the time of repair, capacitors that may have looked good or tested good could have failed since then.
Another issue with a bouncing tachometer is the IC1 chip that is soldered to the circuit board on the tach itself. Over time, these solder joints will fail and cause the chip to randomly malfunction. The fix is easy: re-solder the IC chip. You don't have to remove the old solder then replace it with new stuff. Just re-flow each joint and it should be good to go.
Please remember, diagnosing a tach or speedo problem is a very unique beast. Which is why this thread (and others) are here. The first and important step to recommend is a visual inspection of your tachometer and speedometer boards. That would possibly show any damage or defective components. Furthermore, it is equally important to understand how an aftermarket ECU (PFC or otherwise) sends a tach signal to the speedo board.
Hypothetically, if you swap in a different instrument cluster and you are still seeing problems then it could be one of 2 things:
1. Poor/loose ground to the instrument cluster and/or ECU
2. ECU is not sending the tach signal to the right place or it is intermittent.
Ultimately, I recommend removing the instrument cluster and visually inspect both circuit boards. You may post pics in this thread and I could offer advise when needed.
How does that all sound?
I did a few tests, ran a fresh ground wire to the screw in the back of the tach, no differences.
I ran a wire from the ecu tach output pin directly to the gauge cluster pin, no changes in behavior(with either cluster)
I swapped a cluster that is supposed to be good from a jdm car, and for a few seconds maybe 3-4 times the tach did the jump up thing, and went back to normal, then stayed normal for around 30 minutes of car running.( I tested with the fresh wire from ecu and with out)
swapping back to the other cluster it went to jumping up over half of the time. (reving around 2K the taach was kind of floating around 3K then , went back to reading normal for a while)
so the repaired cluster seems to be effected by what ever is going on way more than this other jdm cluster which has all original insides.
I have sent my cluster back to be reevaluated by the person who repaired it. and he will test it in a test fd also this time vs just on the bench.
im going to run the jdm cluster for now and see if the tach stays accurate for some longer drives.
Thanks for the explanation. Based upon your current description of the problem, I would recommend checking the ground on your engine block. The speedometer board uses Ground Pt 3, which is located on the engine block. It is hard to spot specifically on the schematic because it is very small. That would be my 1st spot to check. Secondly, look at the flex print on the instrument cluster. The tabs that extend into the sockets where the dash harness plugs into should curl out. I talked about it in Post 193, above.
Did we talk about the ground to your ECU? If not done so, please verify that your ECU is properly grounded. I heard from other members that a symptom of a bouncing tach or the speedometer following the tach results from a poor ECU ground. Make sure you check the ground wire for proper mounting. It must have metal to metal contact. It could potentially break free from vibrations that occur from normal driving.
Since your cluster is sent back in for further diagnosis, if they can replicate a bouncing tachometer then you could suggest they resolder IC1 on the small tachometer board. Fresh solder usually fixes that problem.
Getting back to your car, I would also look at the wiring harness on the dash. Take measurements between the connectors to the instrument cluster and to the ECU. Diagram C-1a will help in that endeavor.
In conclusion, I recommend measuring the following wires for any continuity breaks or opens (infinite resistance):
C1-01 Pin 1E to ground (this is Ground Pt 3, so check that ground as an additional but separate step)
C1-01 Pin 4C to B1-01 Pin 1N (ECU) (Mileage Switch/Power Steering Pressure Switch Input)
C1-01 Pin 3F to B1-01 Pin 2B (ECU) (Datalink IG-terminal Output)
C1-01 Pin 3E to B1-01 Pin 1M (ECU) (Vehicle Speed Sensor Input) and Q-01 Pin E (Cruise Control ECU) (Vehicle Speed Sensor Input)
If all of these wires check good then there is still a possibility that the speedo board and/or instrument cluster requires further troubleshooting.
On the original problem that occurred for years
one thing to clarify the tach does not bounce around.when its acting up.
If say I was cruising at 2500rpms, it will jump up to 3500rpmz and stay there for sometimes up to several minutes. ( and will stay incorrect getting farther off at higher rpms)
Sometimes it may only read incorrectly for several second, othertimes quite a while...
Hope to do some troubleshooting and testing this weekend
Hi George, Been reading through much of these discussions. I have a 94 with the ODO no output problem. Having pulled my cluster and waiting on some tools to desolder the speedometer. C3 looks pretty good at first glance from the side view. I'll do some pictures soon. Just wanted to introduce myself at this time.
Thanks for the introductory post and welcome to the forum!
While you wait to desolder the speedometer face you can take a few photos in and around the board. Just make sure to get some good zoom-in shots. You may have to use a flashlight as an external light source to highlight a particular area. You may refer to the photos throughout this thread to help determine the best angles needed.
How long have you had this blank odo problem? Do you plan on doing the solder work yourself?
Well that was short lived optimism. Desoldering stuff finally arrived. C3 was definitely leaky. Pulled it out. Need to clean the board now. got some pics on my phone just need to figure out how to move them onto puter for posting here. Not something I'm skilled at.
05-15-20, 04:15 PM
