92" G30, can I test my "RPM SPEED SENSOR"? [Archive]

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Sceolan

01-21-2008, 02:43

I am suspecting that my tranny (4l80e) don't receive RPM info from the RPM speed sensor. Is it possible to measure if it is sending RPM information to the PCM?

Jody Jack

01-21-2008, 07:33

well only way i know is to find a shop or someone with a scan-tool and hook it up to your dinostic's link ups. it should tell you if it is or isent....

john8662

01-21-2008, 09:22

The correct scan tool might be capable of seeing the RPM, that engine should have a sensor on the oil pump drive, or on top of the vacuum pump.

But for using this for a tach, I'm not sure how this'll work.

J

Sceolan

01-22-2008, 00:23

The sensor is on the Oil Pump Drive Gear yes.

This sensor, along with the veichle speed sensors, sends information to my PCM regarding when my car should shift, doesn'it? Cause I think my veichle speed sensors are ok, and I have adjustet my TPS, but still my tranny shifts to early at full throttle.

Could this be a faulty rpm sensor, or is this not likely?

80Sierra

01-22-2008, 11:50

I was under the impression that 4l80e transmissions had two speed sensors in them. One is internal to aid with shifting, the other external for the PCM to use for your speedometer signal etc.

I could be totally wrong, but I'd be looking to see if maybe one of the two sensors on the transmission itself had failed...

highpockets

01-22-2008, 13:45

My '94 Sub gasser has a thing called "drac", digital ratio adaper controller. It takes the vehicule speed sensor and sends signals to the speedometer, cruise control, and to the tranny. I had problems with wiring just above the tranny shorting out and stopping the VSS signal. I found a write-up on a Camero web site on how they were reto fitting new engine and trans into older (pre-ecu) bodies. My repair manual ignores this part. Hope this helps.

Sceolan

01-23-2008, 04:20

Yes, the tranny do have 2 veichle speed sensors, isnt it a way to measure these, to see if they are working? My speedo works fine, no problemo there. But the wires from the RPM sensor also goes to the PCM, so I guess this one also have something to do with how the tranny shifts?