1993 GMC Sierra TBI 5.7L V8 - don't have 5v to TPS!! Advice please!

[masher41]

Getting Codes 22 and 34, TPS and MAP. Pulled plug off TPS and tested grey wire to battery -, I get 0.025VDC with key on and engine not running.

Here's my question:. I understand the 5VDC comes from the engine computer in the glovebox, but is there anything in the circuit between the computer and the TPS(other than the wiring) that I need to look at? Any advice on narrowing my trouble shooting efforts down?

 

[Schurkey]

Get the wiring diagram for your vehicle, find out everything on that circuit.

Trace the wires, you'll likely find a break or a ground.

MAYBE you have a failed computer that no longer produces that 5V signal. Possible, not likely.

 

[masher41]

Get the wiring diagram for your vehicle, find out everything on that circuit.

Trace the wires, you'll likely find a break or a ground.

MAYBE you have a failed computer that no longer produces that 5V signal. Possible, not likely.

Got the schematic, traced the wiring down, had continuity and no ground on wire, I conclude it's a bad ecu, got one on order. Noticed existing ECU is labelled "remanufactured", so we'll see what happens with new one.

 

[Schurkey]

Did you test for that 5-volt supply at the harness connector where it plugs into the ECU?

Did you disconnect the other sensors that receive that 5-volt supply? If one of the sensors had a short-to-ground, it'd disable the 5-volt supply to all the other sensors in that circuit.

 

[masher41]

Did you test for that 5-volt supply at the harness connector where it plugs into the ECU?

Did you disconnect the other sensors that receive that 5-volt supply? If one of the sensors had a short-to-ground, it'd disable the 5-volt supply to all the other sensors in that circuit.

no, I didn't check that but I will. thx for the tip!