Troubleshooting a GM (Grand Am) speed sensor VSS
Hi
I'm working on a 1989 Pontiac Grand Am, automatic with a 2.5 liter engine. The speedometer and odometer have stopped working, and I'm trying to narrow down the possibilities.
To start with, I thought I'd check out the speed sensor located on the transaxle. There is a 2 wire harness connected to it, a purple one and a yellow one. Should there be any voltage on either wire (input)? If so, which one? And if there is input voltage on one, verified with a VOM, should there be intermittent voltage (pulsing) on the other wire, when spinning the gear, to send the speed signal back to the ecm or to the instrument cluster?
To test the sensor, I'm guessing the key would need to be on, and maybe the shifter placed in drive?
Any help would be appreciated!