Speedo Not Working

RabbitGTI

Top Post Dawg
Joined
Jul 20, 1997
Location
Wisconsin
TDI
B4 Passat Sedan
A friends car, 96 B4V. Radiator fans ran all the time. Then speedo quit working as well as wonky fuel gauge. We found a ground up gear on speed sensor in transmission and replaced it. Still no speedo. We swapped out the cluster and no difference. Cleaned up all the grounds including the three near the head. While doing all this, the fans quit running all the time. :confused: Any ideas on common wiring between the two or other things to check. Cruise does not work, so signal from VSS is not going to anything. thanks :)
 

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
Did you replace the complete speed sensor at the trans? I would be leery of a sensor where a gear got mutilated. Try replacing the sensor with known good one and see what that yields.

Sounds like you solved your fan problem when you cleaned the grounds, the wonky fuel gauge and inop speedo might not be related to each other.

If the wiring has become a problem with the speed sensor then it most likely the failure will be found in the engine compartment.

Steve
 

RabbitGTI

Top Post Dawg
Joined
Jul 20, 1997
Location
Wisconsin
TDI
B4 Passat Sedan
Thanks. I think we took the gear and sensor together out of a spare transmission and put them in his car. Will have to check. I'm looking at the wiring diagram now.
 

RabbitGTI

Top Post Dawg
Joined
Jul 20, 1997
Location
Wisconsin
TDI
B4 Passat Sedan
We replaced the entire VSS. Voltage to VSS connector is fine with key on. Ground from VSS connector to three wire attachment point is fine. Cluster in diagnostic mode yields

6063
4
3
4
000000 0000
0
0
051

Fuel gauge goes up when key is turned to on. When driving it fluctuates, the speedo is pinned to the bottom, the trip odometer does not work and the odometer remains on the mileage that was displayed when this problem started. Any ideas?
 

Abacus

That helpful B4 guy
Joined
Nov 10, 2007
Location
Relocated from Maine to Dewey, AZ
TDI
Only the B4V left
I encountered something like this a few years ago with a B4. I did the same things you did without fixing the problem. I finally found it when replacing the clutch and transmission. It was chafing in the area between the starter and battery on the wiring harness. I hope you can discern where from the photos, which you can click on to enlarge. Run your hands under the wire loom to feel for areas it may be chafed. It doesn't take much.

Good luck.









 

RabbitGTI

Top Post Dawg
Joined
Jul 20, 1997
Location
Wisconsin
TDI
B4 Passat Sedan
Harness looks fine. Noticed with key on CEL illuminates very dimly for a second and goes out.
 

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
The B4 clusters are not known for being the most robust. I suspect either the cluster is shot or you have crossed wires somewhere in the harness. You should not have a ghost CEL light under any situation.

Steve
 

RabbitGTI

Top Post Dawg
Joined
Jul 20, 1997
Location
Wisconsin
TDI
B4 Passat Sedan
Hi Steve, we swapped out the cluster for one out of the owners parts car. That cluster was working before the car was crashed. The owner also says the ghost CEL has been coming and going for a longtime and he thinks it's related to the cobbled 5th injector wiring the PO installed. Damn, this is a frustrating problem.
 

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
If the replacement cluster performed identically to the original then you have a wiring dilemma that needs to be resolved.

I think there's some good write ups on how to deal with the 5th injector stuff, see if you can't repair the cobbled mess with something that will adequately disable the injector and not give you a CEL.

Good luck!

Steve
 

buttonfly

Veteran Member
Joined
Feb 9, 2006
Location
Texas Corners, MI
TDI
2004 Jetta TDI GLS Wagon
You might find some answers here:
http://forums.tdiclub.com/showthread.php?t=450269

My VSS gear was mangled too, still have not resolved the issue. It is looking like I'll need to crack open the differential to look at the condition of the speed gear, but I want to explore all possibilities before I have to drop the transmission.

If you figure it out, let me know!
 

RabbitGTI

Top Post Dawg
Joined
Jul 20, 1997
Location
Wisconsin
TDI
B4 Passat Sedan
Tried CoolAirVW's troubleshooting from the thread buttonfly posted. Put the broken VSS in the chuck of a drill and gave it a spin with the key on. Speedo works, so it's the gear in the transmission. We have a spare transmission, so I guess it's clutch change time :)
 
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