TPS Error? Codes P0510 and P0120 (1 Viewer)

[ADVFJ80]

Hoping I'm on the right track and asking for some feedback. My '97 80 threw two CEL codes today, P0510 (Closed Throttle Position Switch) and later P0120 (Throttle Pedal/Position Circuit A).

Following the FSM procedure for OBD2, since I don't have the fancy Toyota tool, voltage measured at TPS terminals 1 and 2 read 11.89 volts. According to the FSM, that means I should replace the TPS, assuming I don't have a short in the harness between the sensor and the ECM .

I've not pulled the panels to follow the procedures for the ECM check, but the voltage was stable when I chased the wiring harness and used the Oklahoma wire wiggle-n-jiggle test I learned back home. I'm planning to test that when I can, but am curious if any others have seen the ECM be the problem in this procedure?

Learning what I've learned today, my truck has intermittently given me symptoms of a bad TPS. Some of those symptoms have been erratic idle, odd throttle response (mostly more abrupt than expected), and new today is absolutely abysmal milage (even worse than usual!) according to the scan gauge.

I've got a new TPS and gas cap on the way, but I'm curious if others have had the same codes, and any outcomes aside from a bad TPS?


Thanks,
Randy

 

[jonheld]

but am curious if any others have seen the ECM be the problem in this procedure?

I will only say that in a later model OBD2 FZJ80, it is EXTREMELY rare to see an actual ECU issue.

 

[ADVFJ80]

I will only say that in a later model OBD2 FZJ80, it is EXTREMELY rare to see an actual ECU issue.

Thanks for that. I feel the same way, but am curious if anyone experienced an ECU failure with similar symptoms.

 

[ADVFJ80]

Just wanted to close this out. Followed the troubleshooting guide in the FSM and determined the ECU was fine, and that I had correct voltage in the harness to the TPS connection.

Replaced and adjusted the new TPS as per the FSM, and all codes cleared and all symptoms went away.

Thanks to 'mud for the knowledge base and access to the digital FSM!!

Randy