Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Bad fuse? Or bad PCM?

Working on my Infiniti G37 won’t start, am getting a bunch of these “circuit high input” codes is it a blown fuse? Or bad pcm?

Blown fuses are very easy to check… but why would any input be “high” if the fuse was blown?

Post the codes… the actual P1234 codes, and I’ll make a judgement on the PCM

image image image

When you got a lot of codes it often makes sense to focus on the one w/the lowest number first. They’re ordered so that the lower number codes are ones that are most likely to be problematic to drivability. The p0123 is for the throttle position sensor. Usually that’s a circuit with a variable resistor and reference voltage who’s output voltage varies from a low voltage to a higher voltage as the throttle position goes from slightly open to wide open (like when you press on the gas pedal). That code is saying the output voltage from that circuit is so high it is out of range; i.e. there are no valid throttle positions open that wide. Possible causes are

  • Throttle position sensor malfunction
  • ECM malfunction
  • ECM reference voltage malfunction
  • ECM sensor ground problem

What does the battery voltage measure? At least check the fuse that powers the ecm. Any work done in the engine compartment recently? If so, check for ground wires that didn’t get reconnected, especially between the cylinder head/throttle body area and the chassis ground.

1 Like

The car was in a accident am doing all the repairs to it now. I check all the connections everything is good am going to pull out the car cpu and send it out to get tested/repaired if needed.

I suspect that the ECU is okay. If you haven’t verified that the grounding is okay to the TPS sensors that show code issues I suggest you do that. Also make sure the ECU grounding is okay, though you are getting code errors okay. You should be able to monitor the TPS voltage going to the ECU with a DC voltmeter while moving the throttle.