Jetta GLS Speeometer Problem

[borayar]

I have 1996 Jetta GLS 2.0 SOHC with speedometer problem. About 20 minutes after hitting the Interstate, the indicator flops up and down <OR> just dives down to zero.

The Transmission sensor and relay have been replaced. Just swapped out plugs, wires, distributor, and rotor.

Any ideas on what is the cause <or> where to look now?

[boschmann]

I've heard that the problem more often is the plastic drive gear below the sensor, at least on later models. One other question; Is this auto or manual? I believe some automatics have two speed sensors, one for speedo, one for trans module.

[borayar]

Originally Posted by boschmann

I've heard that the problem more often is the plastic drive gear below the sensor, at least on later models. One other question; Is this auto or manual? I believe some automatics have two speed sensors, one for speedo, one for trans module.

It's Auto.
Oh, the sensor stuff was done by the dealership. I did the wires, plugs, cap, and rotor.

I bought the Jetta used, but also bought an extended maintenance agreement - which has paid me back almost three times over and keep my cost pretty low.

I've got the Haynes book, but will probably head to the library to copy a few pages from the Bentley book if the resolution is not covered by the extended maintenance coverage.

[borayar]

Went to the local library and copied a few pages from the Bentley book on the sunroof and the driver side door. While I was there, I decided to look up the speedometer and cruise control, since I'm having trouble with both.

Well, guess what? Seems that the troubleshooting guide for the cruise control includes the speed sensor off of the tranny, which is also a component of the speedometer problem. Well, the sensor has been changed, so it appears that the cruise control may be the root cause of my speedo problem.

Good thing. Cruise control is covered under my maintenance Agreement. Yes!

[boschmann]

The cruise control runs off of info from the trans control module, which uses the other speed sensor - left (of car) front of trans with white, yellow & black (shield) wires. Speedo runs off the other sensor on the top backside of the trans with the white/blue wire. It would be unusual that the speed sensor causes the cruise to go bad, usually it's the switch at the brake pedal or a vacuum leak. Besides if that sensor was bad it wiuld not shift properly. Again, I'd check the plastic drive gear under the sensor for the speedo.

[borayar]

After many trips (and usage of vacation time) to sit and wait for the VW Techie to troubleshoot the problem [which I finally proved to them by taking the techie on a test drive to see the speedo flop and fail], the problem turns out to be .........

a loose wire going into the fuse/relay box!

Next problem? The techie's explaination to the Maintenance Agreement company led them to believe that the problem was all about a fuse!

Solution? A calm and to-the-point discussion with the Service Manager about the differences between a fuse wire and a relay wire. The Service Manager is calling the Maintenance Agreement company today. I expect a complete repair soon - at no cost to me!

Many thanks to all who gave suggestions - especially Boschmann.

[pedrog]

Really? What have you heard? My speedo is dead, the dealer said it's the assembly in the transmission and wants 1200 for the repair (ouch). Any info that you can share would be mucho appreciated.

Originally Posted by boschmann

I've heard that the problem more often is the plastic drive gear below the sensor, at least on later models. One other question; Is this auto or manual? I believe some automatics have two speed sensors, one for speedo, one for trans module.

[borayar]

Well, the saga continues.

The 'approved' repair was done was to do 'bypass surgery' from the lead-in wire to the fuse/relay box to the exit wire leading to the speedo - bypassing the fuse/relay box entirely.

Ten minutes after I left the shop - the speedo dropped.

Now, we're back to troubleshooting the root cause.

Sorry to be negative, but could it be that I was just unlucky to pick a dealer with a staff of idiots?

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To answer the last poster's question (I hope): Yest there are two sensors on the Transmission. If you don't have the Service Manual, you can check out a good sized library section and find it there.
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Back to the shop.........