VSS location

[mailliw]

1987 Pontiac Grand AM, Auto trans. Where is the vehicle speed sensor located, and would it mess with the idleing as well the speedometer and tach.
Thank You;
William

[Knifeblade]

VSS is on the transmission, usually located on the R rear of the engine compartment. The VSS sends a pulsing signal to the ECM, and controls operation of TCC system, shift light, cruise control, and activates EGR system.

I don't believe it will fuss with idle, or speedo/tach operation.

[Knifeblade]

U can test the VSS for proper operation. Backprobe the VSS terminals with a high impedance Voltmeter [set to AC voltage scale]. But```````

Ya have to raise the drive wheels up off the ground, start the engine, and put in gear. Rev the engine slowly, VSS AC Voltage read should increase, as drive [in gear] speed increases. If not, VSS is toast, most likely.

[mailliw]

Thank you, looks like I will have to look at something besides VSS for solution to my problem.
William

[Knifeblade]

NP, William, I don't think the VSS is the source of your symptoms, although you don't state the symptoms. But, if ya feel confident about backprobing, and have a few minutes [actually about an hour or so, given jacking up, and unjacking] it worth checking the VSS out anyway.

Tam

[mailliw]

1987 Grand AM 2.5 L, auto trans
Symptoms; Was running fine,check engine soon light came on, started going dead at stops(low idle), speedometer and odometer stopped working. Can improve idle some by boosting idle screw length, but odometer and speedometer still dead, then sometimes check engine soon light starts flashing, speedometer starts jumping from 0 to about right speed(on-off,on-off) idle speed or tach rises and falls, engine runs rough. Then when I restart it,the speedometer might be dead and idle low or it might be jumping up and down.
Thank You;
William

[Knifeblade]

Ruh roh, ya got a bad send-unit or bad wire somehwere. I suggest get the ride scanned, see if the ECM can advise.

[mailliw]

Tried scanning, light want flash so I can't scan. Where would send-unit be located?
Thank You
William

[Knifeblade]

K, is the panel electronic or cable-driven?

[mailliw]

Panel is electronic. Thanks