P0123 code tried all the usual 2001 GC 4.7
02-19-2017, 02:20 PM
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Model: Cherokee
P0123 code tried all the usual 2001 GC 4.7
I have read many posts about the P0123 code (TPS High) and possible cause by the clockspring. I need help from the gurus.
Here's what I have done:
Replaced TPS
Backprobed TPS plug with key on 5.1v in, ground checks ok to PCM
and chassis, signal shows 1.17v and goes to 4 v as I move throttle. The book says it should have .2-.9V at rest. If I remove the TPS it will go down to .4V but installed it preloads and is too high. I also tried a Mopar TPS and it's the same as the O'Reilly one.
I put a 220 ohm resister between the signal wire and Gnd and it shows .4 at rest and the code will clear, but comes back upon engine start.
I also just de-installed the TPS so the spring goes to rest but still connected with .3V but the code stays on
Ohmed out all wires to PCM and to the TCM from TPS (my model has a branch to both from the signal wire)
I brought it to a mechanic and they said I need a PCM. Their quote was $1,100 so I got one from a source in FL for $249 programmed. The local dealer uses them since they are not available new.
I installed it but no joy.
Thinking something is pulling up the voltage, I tried the following:
I wanted to eliminate the TCM so I found the signal wire to/from the TCM and cut it - no change but the voltage is exactly the same as the back of the plug.
Pulled the fuses for horn and airbag
Pulled the connectors from the Clockspring ( I had to use heat and create a bracket to keep the wheel puller from slipping off and chipping off the small parts you could grab onto) many hours wasted.
Replaced the clock spring
Tried the second PCM again with the Mopar TPS
Soldered the cut wire and put it back together.
So now I'm stuck. I still see 1.17V from the TPS at rest and know it could be within range uninstalled, but the only way to install requires preloading the TPS sensor a bit. And if I leave it uninstalled and reset the code with the key on, the code comes back upon startup anyway.
Even if I take it to a shop they will charge hours to go through these steps and I don't want to pay that for a vehicle worth a few grand.
What next?
Here's what I have done:
Replaced TPS
Backprobed TPS plug with key on 5.1v in, ground checks ok to PCM
and chassis, signal shows 1.17v and goes to 4 v as I move throttle. The book says it should have .2-.9V at rest. If I remove the TPS it will go down to .4V but installed it preloads and is too high. I also tried a Mopar TPS and it's the same as the O'Reilly one.
I put a 220 ohm resister between the signal wire and Gnd and it shows .4 at rest and the code will clear, but comes back upon engine start.
I also just de-installed the TPS so the spring goes to rest but still connected with .3V but the code stays on
Ohmed out all wires to PCM and to the TCM from TPS (my model has a branch to both from the signal wire)
I brought it to a mechanic and they said I need a PCM. Their quote was $1,100 so I got one from a source in FL for $249 programmed. The local dealer uses them since they are not available new.
I installed it but no joy.
Thinking something is pulling up the voltage, I tried the following:
I wanted to eliminate the TCM so I found the signal wire to/from the TCM and cut it - no change but the voltage is exactly the same as the back of the plug.
Pulled the fuses for horn and airbag
Pulled the connectors from the Clockspring ( I had to use heat and create a bracket to keep the wheel puller from slipping off and chipping off the small parts you could grab onto) many hours wasted.
Replaced the clock spring
Tried the second PCM again with the Mopar TPS
Soldered the cut wire and put it back together.
So now I'm stuck. I still see 1.17V from the TPS at rest and know it could be within range uninstalled, but the only way to install requires preloading the TPS sensor a bit. And if I leave it uninstalled and reset the code with the key on, the code comes back upon startup anyway.
Even if I take it to a shop they will charge hours to go through these steps and I don't want to pay that for a vehicle worth a few grand.
What next?
02-21-2017, 01:42 PM
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Model: Cherokee
does the throttle body have a lot of carbon buildup in it? I have seen a couple where carbon buildup wasn't allowing the throttle body to mechanically operate properly giving faulty signals to the tps.