Know how to check the ref. & signal volts at the sensor?
Identify the power, ground and signal wires on the TPS. Do you have an EVTM?
BK/W - ground/neg.
O/W - signal
DG/LG - ref.
All tests made with the connector firmly seated on the TPS, and key on. DVOM is best. Ability to backprobe at the connector is required. Be careful to not short out while testing...the wiring goes directly to the ECU.
- Check the reference voltage. This is the voltage running through the circuit between the TPS and the ECU. Touch the negative probe on the DVOM to the negative wire connector, BK/W on the TPS, and the positive probe to the positive/ref, DG/LG. You should see 4.00v~5.00v.
If the ref. volts are low, inspect the main harness connector behind the pass. side fender well near the self-test connector near the firewall. Open it up and check for corrosion. Still no joy, start checking grounds and consider doing voltage drop testing.
- Check signal voltage. Touch the positive probe to the signal wire and touch the ground probe to the body/engine, etc. Acceptable voltage range is from .49 ~ 1.22 V with the throttle closed.
Signal volts should change smoothly when the pedal is pushed/released. If the volts jump or don't change, the TPS is faulty, and/or the throttle shaft isn't rotating it correctly for some reason. Confirm the throttle shaft bearings in the throttle body are not worn out.