Bob Mears

My 93 odometer worked on and off for several years. It registers the right miles when it lights up. It just doesnt light up very often. Its a low mile car and I think its time to sell, but I dont want to replace the odometer if it has to go back to 0 miles. Does anybody know if the miles are registered in the speedo itself or a computer elsewhere and I can put a new speedo in (assuming I can get one) and it pops up the right miles?

DaveW

It's probably suffering from a bad solder joint or capacitor - IIRC, there have been several threads on repairing speedometers. Once you have it out it might be worth trying to repair rather than replace.

Gen2n3

iTrader: (1)

Bob,

Are you certain that the odo tracks the correct mileage when it lights back up? From my experience, no mileage is recorded when it blanks out. To answer your questions - the chip that stores the mileage is on the speedo board. A new replacement speedo would read 0 mileage. A used replacement speedometer would have the mileage stored on that chip. It is possible to swap odo chips.

Alternately, the speedo board can be repaired. The electrolytic capacitors are the likely culprits for failure. There are a few threads that cover the repair of the odometer along with a detailed parts list. Have you soldered electronic components before? How confident are you at soldering?

Cheers,
George

Bob Mears

Yes, I think I'm capable of simply re-soldering existing soldering joinnts. I'm not capable of removing and replacing parts

Gen2n3

iTrader: (1)

Bob,

Be mindful, reflowing solder is not a good idea. The old solder must be removed and new solder put in its place. This ensures both mechanical and electrical bonds are maintained. I have a helpful soldering thread on the forum, if interested.

When do you plan on removing the instrument cluster to inspect the speedometer? As another reminder, in order to examine the entire speedometer board, the speedometer face must be de-soldered from the board. Make sure to take plenty of photos. If you have any problems then reach out to me.

Cheers,
George

Bob Mears

You've already convinced me that i dont need to be digging in this thing. I'm looking for someone that I can send the entire cluster to for repair, but so far that isnt looking to good. I cnat find anyone to take the job. Looks like I should just leave well enough alone.

Gen2n3

iTrader: (1)

Bob,

Are you confident to remove the instrument cluster and extract the Speedometer? If so, take pictures of the speedo (fully assembled) at various angles then post them to my Speedo Repair thread. Perhaps we could work something out? PM me when/if interested.

My troubleshooting thread is here:
https://www.rx7club.com/3rd-generati...1118446/page3/

The original thread that discusses instrument cluster removal & disassembly is here:
https://www.rx7club.com/3rd-generati...ometer-599220/

Cheers,
George

rousu

My 93 had an inoperative odometer for almost a year. When the engine was pullled and replaced, and everything hooked up again, the odometer started displaying again without any special attention. The milage it displayed corresponded to what I thought it would be if it had been accumulating my milage all the time it was not displaying.
So, quick and easy might be to check signal/power to the odometer/speedometer display.
One path might just be remove power and let the car computer systems reboot.
Another path might be to unplug and replug the connectors that go to the computer, in case there is a dirty bad contact in the connector plug pins.

(always pleasant to have one free benefit from an engine rebuild)

Gen2n3

iTrader: (1)

Rousu,

Thanks for sharing your experience. It sounds like you got lucky on the odometer repair; in deed, it was a bonus during your rebuild! Perhaps there was something else done to get your odo back to life and its method was lost to time? Most problems stem from leaking capacitors on the speedometer board. The data for the odometer is stored on the speedometer board.

What are you referencing when talking about the car's computer systems - the ECU? Your suggestions have merit for ECU related problems. However, this problem is isolated to the speedometer. In order to check power to the speedometer, one has to remove the instrument cluster. Measuring voltages from multiple connectors is a bit more involved when the cluster is removed. Since it (cluster) is out, removing the speedometer and visually inspecting it for leaked capacitors would be a more logical approach since they are known to fail. Chances are low that the flex print connectors on the cluster were dirty or needed to be reshaped unless these connectors were previously touched. It is likely to see other electrical gremlins appear if these flex print connectors are not properly shaped.

The original thread, referenced in Post #7 above, covers symptoms, disassembly, and repair of the odometer rather well. It should be the 1st thread to read when an odometer blanks out. Basically, use that thread when the odometer blanks out, the odometer backlight is visible, and cruise control cannot maintain constant speed.

IMHO, I believe every FD owner should inspect his OEM speedometer for capacitor damage (leaking, bulged, etc...) whether it works or not. This proactive approach would identify the failed components before it causes a blank odometer and/or causes ancillary damage to the circuit board from leaked acid.

Cheers,
George