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Pete, Technician
Category: Jeep
Satisfied Customers: 27814
Experience:  Over 17 years diagnosing and repairing automobiles various makes and models with some training and certifications.
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03 jeep grand cherokee p0108 code replaced map sensor still

Customer Question

03 jeep grand cherokee p0108 code replaced map sensor still code had 5 volts reference went too test wiring thinking it might be the ecm now i lost reference voltage too sensor and injectors can i get a wiring diagram of the sensor too computer i put power
to the orange wire at the map sensor the ecm was disconnected i noticed the key light is staying on of course the eng no longer starts
Submitted: 1 year ago.
Category: Jeep
Expert:  Pete replied 1 year ago.

Hi my name is ***** ***** I will be happy to help with this today.

Below is a diagram for the MAP sensor to PCM.The 5 volt signal is a direct signal from the PCM to the sensor itself with no other components inline that can affect the 5 volt signal.If you had 5 volts on the orange wire at one point then when checking the harness you lost the 5 volts there is a good chance that there is a wiring fault leading from the PCM to the MAP sensor itself and I would check over wiring for any issues needing repaired.

If wiring is all o.k. the PCM power and grounds need checked and if these are found o.k.and you have no 5 volts on this orange wire with key on I suspect the PCM has failed needing replaced.PCM failure will also cause no injector operation as well here and security issues.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.Thanks Pete.

Customer: replied 1 year ago.
pete something is wrong i noticed now that when i turn on the key on the dash lights normally a second later lights go off all that stays on is the key symbol engine light and low fuel light i had the ecm disconnected when i tried too test the wires when i put power to the the organge wire do you think a destroyed something else can i get a more extensive wiring diagram thanks for helping
Expert:  Pete replied 1 year ago.

I apologize for the delay.

If you had the engine computer disconnected completely when you applied power to the orange wire this shouldn't have damaged anything except possibly the sensor itself.

Are you saying all of the lights are staying on on the dash with this issue now?

Customer: replied 1 year ago.
what is happening is the car running poorly and stalling code po108 tried 2 map sensors same thing then tested for reference volts had 5 volts and ground even had voltage return i figured it was the ecm i wanted too make sure the signal was getting back to the ecm so i disconnect it and the map sensor and applied voltage instead to the orange reference wire thats when the trouble begin no reference signal to map or coils no start when i turn the ignition on all lights come on then shut off and the key symbol and check engine lights are all thats on it does not make sense is it possible to get a diagram of the ecm wiring maybe there is something more with that orange wire unless the ecm just got worst thanks much for your time.
Expert:  Pete replied 1 year ago.

O.k.,looking at the diagram further there is a splice,splice s105.Even with the ecm and map sensor disconnected applying the 12 volts would have sent 12 volts to the throttle position sensor,cam sensor and crank sensor as seen in the link below.Unfortunately I am unable to upload all diagrams on this model here due to all of the pages it would require to upload but below is the diagram for the splice.Most likely you damaged all of these sensors as they are only suppose to receive 5 volts and you applied 12.With the ecm fully unplugged (all connectors unplugged) this shouldn't have damaged the ecm but if any of the connectors were left connected I suspect the ecm is damaged as well here.

Thanks Pete