Speedometer Problems

[dbosell]

I have a 1995 Chev. G-20 van. The battery went dead and when we jump started it, the speedometer started acting like a tach. After replacing the battery, the speedometer doesn't work at all. Before the battery went out, the speedometer worked fine. (The odometer works fine.)

Does anyone have any ideas as to what needs to be done? My son wants to use this for his learners permit, so I have to get it working again soon.

Thanks in advance,

DB

[RNRea]

You probably fried the DRAC module. The speed sensor from the back of the transmission send a signal that is proportional to the vehicle speed (is is often called the VSS for Vehicle Speed Sensor). This signal goes to the DRAC module which converts this signal to one that drives the speedometer (it also feeds the computer and ABS modules). If the van no longer shifts then it is likely to be this module. If the van does shift normally then it would appear that the speedometer went bad, but my odds are on the DRAC module. If you have an email address I can send you an article (pdf format) that describes how the DRAC module works and how to diagnose it. If you are handy with basic electronics you can get another module from the junk yard and replace your old one. Let me know if you would like the article.

[2Rivers]

i sure would like some info on the drac module. i have a 1994 chev van . speedometer does not work abs light on and the transmisson want shift .takes off and stays in first gear.any pdf info would be nice.my email address is [email protected] thanks alot!!!!!!!!!

[westea49]

Yes the DRAC module is probably the problem. I had that happen to me. Isn't it fun to drive 30mph in 1st gear. This will be my last GMC automatic transmission. Love their engines but they will have to pay me to take one of their automatic transmissions.