dsetty

Dang, my speedometer and cruise control just died on the interstate in my 1993 C2 Cabriolet 964. Both worked for a few minutes and then dropped out again for good. No warning lights or any other issues to report. I searched and found that possibly the VSS -Vehicle Speed Sensor 96460621001 is a possible culprit for the speedo, but found nothing of the speedo\cruise combo failure. Also, I did just have the face of my speedo replaced over the winter. I put on a couple of hundred miles with no issues after the speedo install, but you never know. Does the speedo report back to the cruise? Any one have any thoughts? How hard is it to replace the VSS? Speedo repair is easy if I send it in.
Thanks in advance!

Spyerx

Non function speedo will mess up cruise and wing. Wing still going up?

My guess is speedo. Any burn smell or smoke?

dsetty

Nope, the wing is stuck in Manual movement. No speed signals at all then at the speedo, cruise and spoiler. I need to dig around a wiring diagram and check the connections at the speedo and hard solder joints in the speedo. Hopefully I can wrap this up this weekend.

I still think I should check the VSS.

Rocket Rob

What year is your car? The early cars 89-90 have a speed sensor on the transmission that sends a signal to the speedometer. About 20 years ago, my cab's speedo would go to zero while driving and then a few minutes later start working again. My mechanic traced the problem to the sensor. Replaced it and the speedo began working again.

The 91 and later cars use the ABS sensors to measure the speed via a relay looking gizmo in the fuse box.

dsetty

Mine is a 1993.

No ABS lights on the dash, so I assume any ABS related failures would light up the warning light.

I think the 93 models have ABS wheel sensors and a VSS on the transmission.

dsetty

Wow, I fiddled around the transmission and there is no VSS because they went out with the 1990 model as far as I can tell. I do know my crankshaft sensor works perfectly!

Funny thing is the speedo\cruise\wing and work perfectly now. I assume it will fail again. Gotta be in the speedo.

At least I got some time to repair a couple little things while I was in there.

Rocket Rob

Do you know anyone in the area with a 964? Maybe try trading the relay module and the speedo as either could be intermittent.

dsetty

I only know a couple of older 964. The 1989 and 1990 models aren't the same as my 1993. I will open the speedo to check for bad solder joints and figure out the relay.

dsetty

Getting better. I tried a different ABS Relay, Frequency Converter and even soldered the bad looking joints on the speedo. Now the speedo works, but the spoiler light is always on. I did not test the spoiler for automatic deployment at speed, but it does raise and lower manually. I suspect the problem lies in the speedo. Time to crack it open and check solder joints. Maybe a pro can repair it.

John McM

Is the odometer working?

dsetty

I haven't checked. The odometer was preemptively repaired when I had the flaking painted speedo face with a new one a while back. It should be working. Why do you ask? I assume if the speedometer works, the odometer should work as well.

John McM

Because the UAF 2115 chip in the early 964 gauges controls both the speedo and the odometer it helps the fault finding if you know if they both work or not.

dsetty

I thought the speed situation was fixed, but it reared its ugly head again. Makes no difference what ABS Relay or Frequency Converter are installed, the speedo and cruise just randomly quit. The odometer stops as well. I think I'll ship it off this winter to have it repaired. I suspect this all started when I sent the speedo in for replacement of the face that started to flake...

John McM

Please ask them to tell you what was wrong with it. That helps us all.

A914MAN

This is why mine quit


26 year old capacitors don't last forever. Failing caps will probably become very common as our cars reach a certain age.