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  • avatar wern10 04/13/08 2:03 pm PST

    if a scanner or code reader says no commuication all it is saying is that you have a power failure or a ground failure,it doesnt mean the computers bad.have you checked for fuel at the fuel rail on top of the engine to make sure the pumps running,the pcm and fuel punp relay are one in the same...when you turn the key on does the check engine lite come on?if not you need to inspect and test relays for pcm/fuel pump and any and all related grounds, you need to make a small investment in a cheap repair manual to aid you in testithe power and the grounds for you vehicle....if you have an alarm the first place i would check is the alarm ability to stop the jeep from running,and if you have a emote starter you need to make sure the connections are good, clean and tite...the alarm can function just fine but it still connects to the computer via ignition wire,so I wouldnt eliminate that at this point in the investigation.you are lookin for an obvious problem and when it is found you'll say damn how'd I miss that.you'll need to test for voltage toand from the ignition switch to insure the alarm isn't locking out the pcm....if the check engine does not come on with the key you'll be looking for a interrupted power supply or a broken or dirty ground...i hope this gets you started...I'll be here if you need any further assistance I will be glad to help...

Answers

  • wern10 04/13/08 2:03 pm PST

    if a scanner or code reader says no commuication all it is saying is that you have a power failure or a ground failure,it doesnt mean the computers bad.have you checked for fuel at the fuel rail on top of the engine to make sure the pumps running,the pcm and fuel punp relay are one in the same...when you turn the key on does the check engine lite come on?if not you need to inspect and test relays for pcm/fuel pump and any and all related grounds, you need to make a small investment in a cheap repair manual to aid you in testithe power and the grounds for you vehicle....if you have an alarm the first place i would check is the alarm ability to stop the jeep from running,and if you have a emote starter you need to make sure the connections are good, clean and tite...the alarm can function just fine but it still connects to the computer via ignition wire,so I wouldnt eliminate that at this point in the investigation.you are lookin for an obvious problem and when it is found you'll say damn how'd I miss that.you'll need to test for voltage toand from the ignition switch to insure the alarm isn't locking out the pcm....if the check engine does not come on with the key you'll be looking for a interrupted power supply or a broken or dirty ground...i hope this gets you started...I'll be here if you need any further assistance I will be glad to help...

  • wjrecker 04/13/08 3:45 pm PST

    Thanks for your answer, the check engine light doesn’t turn on when I tray to star it, I have change the relays and I got the electrical diagrams and my 2 electrician check all the wiring and they say that there fine. It has 2 alarms the OEM and after market I went to the after market alarm installer and broth him to my SUV and he told me that his alarm was fine and dint not have any problems but the OEM its works fine but I don’t know how to check if the OEM alarm is not looking the PCM. Im going to double check again on the power supply and the grounds hope I fiend it because I have 2 electricians busies my self trying to fix this tam problem..
    PS; Thanks for the info going to double and triple check wiring
    Thanks for your info. If you have other ideas please let me know.
    Isaac

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