HJi all,
I've read every available thread on this subject and have just a few questions regarding what I am experiencing.

Here is the situation at present:
Speedo does not work
Cruise control does not work
Tach works just fine - no erratic behavior at all
All other cluster gauges work fine
All interior/exterior lights work properly
Flashers and directionals work fine
Heat/air work fine
No shifting issues
Brakes work fine but act like the ABS is activating during slow stops with a single 'release' event before coming to a complete stop - on firm stops at speed there's no ABS activity detected.

So, should I:
Replace the speedometer sensor?
Replace the Transmission/ABS sensor?
Replace the cluster?
Or what?

Many thanks for your valuable insights...

 

First thing to look at would be the VSS. Have you checked for codes?

 

So, should I:

Replace the speedometer sensor? = vss that glc mentioned

Replace the Transmission/ABS sensor? ABS sensor for the rear is on top of the Diff.

Replace the cluster? No
Or what?

Good luck

 

Look at the sensors and the 'exciter' area behind you front disks (rotors).
Wire cut or bent and fraying, follow it to it termination point?
Mud up around the sensor? Metal 'fur' attached to the sensor?

 

I don't think the 97 had 4 wheel ABS, just rear?

 

You're probably right glc, but he refered to the trans ABS sensor. If it has 4wheel ABS the sensor is on the pumpkin, not the trans.

I stand corrected.

 

I just did a bit of research - rear ABS was standard, 4 wheel ABS was an option. The rear ABS uses a differential-mounted speed sensor, the front ABS uses sensors at each front wheel.

Now - I believe what I'm calling the VSS is also known as an OSS - this is mounted on the transmission and drives the speedometer and provides a speed signal to the ECM.

I don't know what the interaction might be between the 2 systems - it's possible the ABS uses a signal from the VSS so it can compare wheel speed to vehicle speed?

The VSS appears to be pretty cheap.

 

You are quite correct, glc.

I'm clear on what parts are involved and what they do. How does one 'check' the OSS or ABS sensor? I'm trying not to buy those sensors only to find out the cluster electronic circuit board is the problem. Any way to sort that out with what is and what is not working?

For example, if the tach is working but the speedo is not, does that indicate an OSS sensor malfunction or not? Do they both us the OSS? If so, it points to the cluster as a problem area.

And for cruise, should I assume the rear ABS is needed? The ABS light comes on and goes off like it should at startup so I have no reason to believe it's a problem. May be pointing to the OSS as the cause?

Thoughts please...

 

No, the OSS has nothing to do with the tach. The tach is showing engine speed, not vehicle speed. ABS has nothing to do with the cruise control that I'm aware of, but with no OSS, no cruise.

Pull the OSS and make sure the gear is intact.

 

Thanks glc for the clarification - that was the direction I needed to know to go in. I've heard the gear can break/chip and lose a tooth or two rendering it inoperable.

I believe the cluster electronics and speedo interact for cruise control operation so maybe a new OSS is all I need. I'll start there.

 

Well, the cruise control needs a speed input - with no way to determine speed it thinks you are going 0 so it won't engage.

 

Right on, glc.

Now, could the momentary 'release' of the brake pedal during slow stops be attributed to a faulty ABS sensor on the differential? Doesn't happen at higher speeds so can't seem to attribute it to anything else unless faulty speed readings from a broken speedo is confusing it (I tend to doubt that with basic ABS sensor/slotted wheel technology). I can replace it for about $15.

 

If it's only 15 bucks, it wouldn't hurt. The OSS isn't much more than that.

 

Yeah, OSS's are about $35 shipped from Rock Auto - I'll look at doing both when the weather dries us out. Only concern is whether the cluster electronics are any issue - a much more expensive part to replace.

I'll be really tickled if all these functions return to operation with such little work and expense - my poor brother in VA owns a '99 Audi A4 and has spent hundreds just fixing his CC - still not working. It's a rat's nest of technology even the local dealer can't figure out.

 

Well, if the cluster is in fact bad, you can get one out of the boneyard. No PATS on a 97, so you don't have an issue with the cluster "married" to the rest of the electronics.

Now - I'm getting confused again. Looks like a VSS is gear-driven, but an OSS uses magnetic pulses. If I'm not mistaken, you have a gear-driven VSS, I don't think you have an OSS. I don't know if a VSS comes with a gear, and you have to have the right gear for your tire size and axle ratio.