No Power To VSS

[Va6622]

I have a 1989 Silverado 5.7 350, automatic. Speedometer stopped working. Replaced speed sensor. Speedometer still didn't work. With engine running, I checked for power at connector that plugs into the sensor. Not sure what voltage should be but my voltmeter showed zero volts. Its a purple/white stripped wire and a yellow wire. Any help appreciated.

 

[BeXtreme]

VSS is a hall effect sensor. You wont have any voltage on that with out the truck driving. Basically as the metal tone wheel goes past the magnet in the sensor, it creates a voltage pulse between the two wires. If you replaced the sensor and it didn't fix it, you either have a broken wire somewhere or a bad gauge.

 

[Va6622]

Thanks for the info. I'll keep troubleshooting until I find a solution.

 

[PlayingWithTBI]

If you replaced the sensor and it didn't fix it, you either have a broken wire somewhere or a bad gauge.

Or a bad DRAC/VSSB which is mounted on the cluster for 88-91 models. The VSS sends the signal (~2000 PPM) to the DRAC/VSSB which converts the signal and sends it to the speedometer.

 

[Va6622]

Should I look for a schematic to locate the DRAC/VSSB on the cluster and also, how could I test it to see if it is bad?

 

[PlayingWithTBI]

Should I look for a schematic to locate the DRAC/VSSB on the cluster and also, how could I test it to see if it is bad?

IIRC @someotherguy did a write up on calibrating these for different gears and/or tires. Maybe he can chime in - Richard?

 

[PlayingWithTBI]

Should I look for a schematic to locate the DRAC/VSSB on the cluster and also, how could I test it to see if it is bad?

Here's some FSMs

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

 

[Va6622]

Desert Old Guy I want to thank you for taking the time to post the link to all of that information. Much appreciated!