Error Code 51 Diagnosis

[cferry7]

1989 Toyota Pickup 2.4L 4WD Manual Transmission

Receiving Error Code "51" while jumper wire connecting TE1 and E1 Diagnostic Connector Pins.
Code 51 suggests a "Switch Signal Error" : Suspected cause areas : ECM, A/C On Switch, A/C Amplifier, CTP Closed Throttle Position,PNP Park Neutral Switch per Haynes Manual.
Currently, the A/C Belt is not on the vehicle.

Has anyone had a experience with this Error Code on a similar vehicle ?

 

[Riggter]

Error code 51

I just had that same one come up and the end result was my Throttle Position Sensor was bad. Had it replaced, code went away and now she purrs like it's supposed to. I'm also running a '89 2.4 22RE in a 4runner.
Also pulled up code 52 which is the knock sensor. Hopefully you don't have to replace that one too. $pendy little sucker.