Hello and PLEASE HELP!
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Joined: Jul 2017
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Hello and PLEASE HELP! Thank you so much for the add, I do not have. Camero but your group had the most info on a GMC P0342 style issue and I have a monster on my daughter truck that I have spent 8 months trying to fix and it is emissions time.
It is a 1999 GMC Sierra 5.3 with an impossible P0342 issue but it runs great. So far I have done the following:
New ECM
3 NEW Can Sensors
New Crank Sensor
Bypassed all three wires with jumpers black to the ECM
New Plugs and Wires
New Battery
New connectors
Numerous small things
Also ran a bore scope down and the rings and stuff look great.
By adding jumpers from the Sensor to the ECM the code finally went away. As soon as I put it in gear it pops as pending again. So I took the harness off and checked voltage. The low voltage reference wire reads fine until I take it out of park and it drops to zero. I get 4.3 volts on one wire, ground, and 11.7 volts between the three wires. As soon as I take it out of park the low voltage goes to Zero. Does anyone have any ideas. I can start it a dozen times and no P0342 but as soon as I take it out of park it pops as pending on several scanners.
Thank you ahead of time for your help and it seemed as this group had the most P0342 experience.
It is a 1999 GMC Sierra 5.3 with an impossible P0342 issue but it runs great. So far I have done the following:
New ECM
3 NEW Can Sensors
New Crank Sensor
Bypassed all three wires with jumpers black to the ECM
New Plugs and Wires
New Battery
New connectors
Numerous small things
Also ran a bore scope down and the rings and stuff look great.
By adding jumpers from the Sensor to the ECM the code finally went away. As soon as I put it in gear it pops as pending again. So I took the harness off and checked voltage. The low voltage reference wire reads fine until I take it out of park and it drops to zero. I get 4.3 volts on one wire, ground, and 11.7 volts between the three wires. As soon as I take it out of park the low voltage goes to Zero. Does anyone have any ideas. I can start it a dozen times and no P0342 but as soon as I take it out of park it pops as pending on several scanners.
Thank you ahead of time for your help and it seemed as this group had the most P0342 experience.
Thread Starter
Registered User
Joined: Jul 2017
Posts: 2
Likes: 0
Anyone with any idea. Also I wonder if I find another low voltage source and wire it in will it take its place for the ECM. I am thinking about unplugging the sensor on the tranny and check if it is causing a dead short on the low voltage. Wonder if it is the park neutral switch.
