When I replaced mine the old one fell apart in my hands. Even then it worked once in a while. I paid about $20 at Napa.

 

Well, the new part doesn't work any better than the old part. They get between 5 and 15 miles before the error comes back.

I will look more closely at the wiring. Any suggestions?

Dan M.

 

mine fell apart too, worked intermittently for a little until i had time to change it out (only a few days) and when it came out i could not even compare them because it was in pieces. Got a replacement from napa and have had 0 issues since installing the new one. only took about 20 min from start to finish to change it out too. good luck

for the record, i have a 98 1.8T manual FWD AEB

 

Still need help...

Update:

I cannot see anything implausible on the Vag-Com graph for Vehicle Speed. Would/should such a signal show up on the graph???
[1.8T, AEB, 5-spd Manual]

Still having intermittent problems, with new VSS sensor.
VSS Implausible Signal is still the "only" CEL code. This is frustrating to me because it is (to me) not a very useful code.
I have NOT checked/cleaned the connector at the back of the Instrument Cluster. All other connectors in the signal path appear to be OK, and have been cleaned (DeOxit, and DeOxit Gold). I will check them again.
I'm tempted to replace the instrument cluster, but don't want the extra expense or headache.
I would like for this code to stay away.


I am now having an additional code from the O2 sensor:
16518 - Oxygen (Lambda) Sensor B1 S1
P0134 - 35-10 - No Activity - Intermittent
Could they be in any way related? I don't think so.

Anyway, I'm now having a little bit of fun with Vag-Com, and here is a graph from a recent re-set of the CEL:

The CEL light came on near the last vertical grid line on the right, just before I pushed in the clutch and had the Engine RPM die down. I cannot see anything in the graph worthy of calling an implausible signal. Perhaps it doesn't graph the implausible ones?

16885 - Vehicle Speed Sensor
P0501 - 35-00 - Implausible Signal

ETA: On some recent long drives in the hot weather, I did for the first time see some fluctuations in the Speedometer -- Expected Speed +/- about 5mpg jiggling back/forth. now, THAT I would call implausible signals. And I would expect that those would be logged on the graph.

 

Are the "vehicle speed sensor" and the "engine speed sensor" the same? I'm having some issues with this as well.

 

Are the "vehicle speed sensor" and the "engine speed sensor" the same? I'm having some issues with this as well.

nope. vehicle speed sensor is that which allows you to determine how fast the car is going.

 

Dan, did you try replacing the speed sensor?

 

Yes, that was the first thing I did. Cheap and Easy to do, but it did not make this problem go away. I'm still running with the new sensor I bought, I didn't put the original back in.

I have some more graphs (but not with me right now) that show the speed sensor sending implausible signals which display quite clearly on the graphs. I looked again, and cleaned again what I think are the connections in this circuit, from the back of the Instrument Panel into the Engine Compartment, and down to the Speed Sensor on the Transmission. Maybe I'm missing something or not cleaning correctly or I'm looking in the wrong places.

There was a Instrument Panel in the classifieds recently that had (at the time) the appropriate mileage on it (~185,000 but now I have ~191,000) I don't think it's been sold, but I don't want to swap out that part without knowing the root cause.

In the meantime, I am having several other issues (automotive as well as life in general) that are more pressing than this particular one, so I'm allowing this one to be ignored for the time being. And I'm ignoring my non-working cruise control system as well. I believe that the Speed Sensor is an important part of that system, but it is not the part that is preventing that system from being operational.

As usual, any and all advice is welcome and appreciated.

 

Having an issue with my 2003 W8 it it looks like the ABS Module may factor into the equation. I get two codes: P0318 Rough Road Sensor A Signal Circuit, and P0501 Veh Speed Sensor A Range/Performance. I'm tempted to throw in a VSS before I rebuild the ABS Module just to be sure.

 

just curious... have you pulled and wiped the sensor faces for the two front ABS sensors?

 

Ahhhh. No. I have not ever pulled out the front ABS sensors. It might be worth a try. I did have the ABS Electronics rebuilt some time ago, and have been ABS-Error-Free since then. I suppose that doesn't automatically mean that all of everything is OK in the ABS world.

For an example of implausible VSS signals, I offer the following graph. Vehicle speed signal is shown in Red, Engine speed is shown in the other color (yellow or green, whatever). This is 1.8T manual transmission, while running in gear and clutch engaged (until the end) so I think that "vehicle speed changes" should be equivalent to "engine speed changes". Implausible signals indeed.

 

I've heard about that VC-Scope software. Where can I get it and the cable?

 

I'm using the Ross-Tech hardware and VCDS software, full version, also known as VAG-COM. Ross-Tech: Home

It wasn't inexpensive, but being able to do all the things that are possible is very nice. Also to support the developers and the development of this fine hardware and software gives me some of what I suppose are those fabled warm fuzzy feelings.

 

Very curious to see what happens here. I have had the same problem with my car (03 1.8t 5mt) for the past 3 years and cant get it resolved. I replaced the speed sensor and traced wires and cleaned the connection to the instrument cluster. My cruise control doesn't work either...so we're pretty much in the same place. I wonder if a bad cruise control stalk could somehow cause this problem? Hopefully we can both get this solved as it sounds like we might have the same thing causing this!

 

Any luck with this problem yet? I have some info I learned today that might be helpful in trouble shooting. I talked to a dealership mechanic and he pulled up the wiring diagram for me. It looks like the sensor is read by the instrument cluster first, then sent to the ECU. It's sent via a white wire with a blue trace. It comes out on pin 3 on the blue 32 pin connector at the back of the cluster and goes to pin 52 on the 121 pin ECU connector. Id check for continuity between those points and see what you end up with. I had continuity between the two, but i could touch any ground point and still have continuity which doesn't seem right to me. Am I correct in thinking this shouldn't happen? Sorry for the slight thread jack, just seems like we have the same problem and I'm trying to get this CEL that's been on for the past 3 years to go away!

 

Any luck with this problem yet? Sorry for the slight thread jack, just seems like we have the same problem and I'm trying to get this CEL that's been on for the past 3 years to go away!

No luck yet, but I almost have my Passat returned from my kids at college. I did get to visit it last weekend, and inspect/clear codes. Of interest was an ABS code "00285 - ABS Wheel Speed Sensor; Front Right (G45), 35-00 - - ".

So I'm hanging onto hopes of Jay's idea to clean the ABS sensors. I'll have the vehicle back in a couple of weeks, and will give the ABS sensors a quick looky-loo and cleanup if possible.

For wiring, I just followed the diagram from the sensor to the instrument cluster, and tried to clean the connections along that route. I don't think I went as far as the ECU, but I'll take a look at the diagrams again and see if it makes sense to me.

It bugs the heck out of me that such a minor and (it seems to me) inconsequential stupid little inconsistency can turn on the MIL/CEL. It would make more sense if I had automatic transmission or if the Cruise Control worked (someday, someday...).

 

just thought of something else, Dan. there is a speed sensor in the transmission, as well. it might be a good idea to take a look at it - it is, as far as I remember, about half way back, slightly left of top (from the driver's perspective). I remember seeing one that Mike Van Gelder had that was nicked and had to be replaced...

 

Thanks for thinking of me, Jay. Can you give me more info about this? I have the 5spd Manual transmission, and I have not seen any hints about speed sensors other than the one on the drivers-side axle (which I have replaced already).

 

oh, crap. I had completely forgotten that you had started with that one early on - we're talking aboout the same one. mea culpa...

 

Maybe not related:
I swapped engines (1.8T AEB) from my 1998 A4 quattro into my 1998 Passat FWD. Moved the whole harness including ECU plugs over.
For some reason, ended up with 2 BLUE connectors, but only one ECU plug.
One can be traced to the driver side drive shaft, the other goes toward the engine, driver side and disappears in a wire bundle under the intake.

I suspect donor car/engine was original (hence still in cable bundle), and receiver car (Passat) had it once replace (hence out of bundle), and that one was still on the transmission (FWD), which I reused.

Initially, I plugged one in, got a VSS code. Swapped the connectors over. Had erratic speedometer (zero speed, then actual speed) for a wheel. Left it like that (while troubleshooting FMIC pipe/hose issues). Now has been good for a while. No idea why it now works (or was erratic before).

 

Well, kind of back from the dead with a small update.

1. I had to replace the front right ABS sensor, because while trying to remove it for cleaning, it got broken. Anyway, it was stuck in its hole very tightly, and was dirty on the ends, and had been rubbing against the axle at some point in its life. The replacement part price from "that auction site" wasn't too bad. I ended up with one that has the connections for the brake pad sensors included in the wiring harness, so I just cut those off as I have nowhere to connect them to.

2. With replaced ABS sensor, now no more ABS problems yet.
> most recently was ABS beeps on powerup, dead sensor, from mishandling while trying to remove it.
00285 - ABS Wheel Speed Sensor; Front Right (G45)
30-00 - Open or Short to Plus
> before this, there was intermittent ABS beeps, often associated with "high" speeds, appx. 80mph. I think it was the same code, except without the detail of "Open or Short to Plus". I forgot what the code was, but it often cleared itself.
> upon installation of new ABS sensor, but apparently without it pushed far enough into the hole, I could roll about 20 feet before ABS beeps again, with an error about Right Front Sensor, I didn't save it.
> I have driven about 80 miles since then, but not at "high" speeds, no more ABS beeps.

3. But still have Vehicle Speed Sensor Problems:

a. Still get this error message after a few miles, but the CEL does NOT come on with it as it did before:
16885 - Vehicle Speed Sensor
P0501 - 35-00 - Implausible Signal
b. There is no reading of vehicle speed inside the VAGCOM software. It just reads "0 kph".
c. The speedometer in the dash displays what appears to be normal speeds, and the needle appears to be steady. Previously, the speedometer needle would jump up/down fairly often.

Plan now:

I will look for my original vehicle speed sensor, and reinstall it into the car sometime, even though I don't think this is the problem.
I will clean and lube the contacts going to the vehicle speed sensor, even though I don't think this is the problem.
Someday I will hunt around for the White/Blue wire mentioned above going from the dash display to the ECU. I think something like this may be the current problem, because now the dash display seems to be good, but VAGCOM gets no speed signal from the ECU.
I will kind of ignore it, as inspection is due end-of-month and at least the lights appear to be staying off for now.

Any useful advice is most welcome as always.

Dan M.

 

Reviving this thread because Dan's car and VSS issue are now mine.

I have not been able to use VCDS on it yet. Generic code reader gives me the p0501 code as expected. I can't get down to only two readiness codes not set (that I need for NYSI) before the MIL pops back on because of this code.

I haven't had the time to dig around looking at the wiring or anything yet, but I did find on Audizine that the magnetic ring inside the diff cover could be bad. But if the speedo works and the ECU was reading 0 mph, then it must be the connection between the cluster and ECU, right??

 

Hi zak99B5, I hope you have good luck with this annoying intermittent implausible error!

My next plan was going to be to replace the 2 wires from the VSS -- 1 to ground (brown) , and 1 going into the ECU plastic container, and onto T10b (Black) connector, Pin 9 (red/brown). I have another VSS harness connector (from junkyard) that I will put into your care package.

Other observations:
1. For my "new" B5 Wagon, the speed display remained at dead 0 all the time. I found there was some problem with the ground wire from the sensor up inside the harness, as in it was broken. I securely attached that brown wire from the sensor to a good ground, and now all is good.
2. In the car that you have, something went wrong with the Starter Solenoid wire between its connector inside the ECU plastic container and the starter. I replaced that wire and all became good.

The point being, that I have seen some degradation to wires inside the engine compartment without obvious reasons. These observations have been conductivitypen, and the Implausible VSS signal is "faster than expected speed" per my graph above, so I'm not sure how that would work. But anyway -- try to replace those 2 wires to the VSS sensor.

I hadn't tried to connect the VAG-COM to the speed indication for some time, and I don't remember my experience above with "0 speed in VCDS". That could equally well have been caused by operator error or caused by actual lack of signal.

And there is also that white/blue wire (A27 Vehicle Speed Signal) between the instrument panel and the ECM.

Good luck!

Dan M.

 

Since the speedo works, I will focus first on the white/blue wire from the cluster to the ECM. Redoing those grounds couldn't hurt either.

I looked at the freeze frame data on the generic code reader for when the DTC was set, and the engine rpm was 2k but speed registered as 0 mph. So I think the ECM is not getting any speed signal.

I am out of town this weekend, so it will be some time before I get get deep into it.

Thanks.

 

I have been doing some internet searching and found a thread on vortex that listed the pins for the VSS from the speedo (#3 on the blue) to ECU (#54).

When I got home from work, I opened up the ECU box and pulled the cluster. I found said pin locations and busted out my multimeter. Open circuit from #3 on the cluster connector and #54 on the ECU connector. Aha.

So I started pulling back the sheathing from the blue cluster connector, found the white w/ blue wire, and found a factory splice. After I took off the rubber insulation, I could see the connection of the 4 wires (1 in, 3 out) was green and corroded. Oh ho!

Clipped off the factory crimp, stripped the four wires back a bit, and used a wire nut to connect them. I am starting to feel it now.

Did the same 3 to 54 pin test and..........open.

Dejectedly, I put the car back together. P0501 code still there. Cleared it. Then I drove it for a couple miles. MIL did not pop on. Scanned it when I got home and all but one monitor has now passed readiness.

I don't know if the P0501 is fixed or about to pop back on, but I do know I can drive for as far as I did today without the MIL coming on AND passing enough readiness tests to pass NYSI.

I will try to get it inspected tomorrow and update.

 

MIL popped on after driving a bit over a mile this afternoon (total of about 6miles) going to get the inspection done. Cleared it and drove the rest of the way, but there were 3 monitors not ready.

So it looks like that corroded connection was not the issue.

Are the pin numbers I have correct for VSS out from speedometer (3) and in to the ECU (54)? And is it indeed the white with blue stripe wire out of the cluster? What about the color code of the wire that feeds the ECU the VSS signal--I want to bypass it.

Thanks for any help.

 

I know your pain.... My version of Electronic Service Information System gives me the following information (reference for 1998 Passat AEB) for the VSS signal out from speedometer and into ECU (pdf file pages are available, just ask):

Wire color, for its entire length: ws/bl (white/blue)
Connector Pin on Dash Display Unit: T32a/3 (32-pin connector, blue, on instrument cluster)
Connector Pin on ECU: T80/20 (Connector, 80 point, on Motronic Engine Control Module (ECM) )
Connector Pin that it passes through on the way: T10d/9 (10-Pin Connector, brown, on protective housing for control module, in engine compartment, left)

As a point of information or reference, the same source says that the T80/54 (Pin 54 that you mention) is a black/red wire that goes to the Intake Air Temperature (IAT) Sensor G72

I had great hopes that the corroded connection you found would have been the solution. Keep working on it, you will find the answer soon I hope!

 

Thanks for the info on the ECU pin, Dan. That's the 20 pin, right? When I pulled the ECU, it seemed that the pin numbers continue from one connector to the other (like, last pin on one is 52, and the first on the next is 53).

All the wires disappear into the molex housing (or whatever) well before I can figure out what color wire goes to which pin.

 

Dan is that brown ten-pin connector one of the few that are in the ECU box behind where the ECU itself sits? I was looking at them, but the wires from there don't obviously lead into the harness that enters the ECU box from the front and them connect to the ECU.

 

Yes... it appears as if the pin numbers continue from one connector to the other on the ECU, as you have noticed. The VSS signal is supposed to come into pin 20. The pin numbers are molded into the plastic of the ECU, one number at the beginning of each row and one number at the end of each row. Sometimes they are hard to see.

The brown ten-pin connector is inside the black plastic housing along with the ECU. There are at least four 10-pin connectors mentioned at the same location in the wiring diagram for the ECU (black, brown, yellow, blue), with the wires going all over the place from there.

 

Awesome--I have some digging to do. Any idea what the VSS signal coming out of the cluster should look like on an analog multimeter? Or do I need an oscilloscope?

 

Well, had one victory today. I was able to reset the light and drive around long enough to get down to just two incomplete monitors.

Pulled into an inspection garage, got the sticker, then about 100' down the road the MIL pops back on. Well, now I can drive around legally and have a year to get this pesky VSS issue resolved (though I plan on fixing it as soon as practical).