1997 Jeep Grand Cherokee 4.0lt No Start

Maurice Business Development Manager Geebung, Australia Posted   Latest  
Question
Drivetrain
Crank / No Start

I have a 97 jeep Grand Cherokee 4.0 lt no start, the customer has fitted a new ECM

There is no spark, or injection ground control but there is power to them. 

Powers and grounds to ECM are good, and good cam and crank patterns going to the ECM. 

Problems with the Automatic shutdown relay ground control and fuel pump relay ground control, when grounding I have about 5 to 6V voltage drop as the ECM is trying to ground both relays. I can bypass both relays by jumping the switch side but still no spark or injection control. 

I suspect the problem is in the ECM. But I have to consider the fact that the owner has replaced ECM already. I asked him for his old ECM but he no longer has it. 

The other strange thing that is going on is when you switch on the ignition all the warning lights illuminate but then they start to go out and I have not cranked the engine. You can see this in the attached video. After doing this video I was showing my staff and all the lights went out including the SRS light and seatbelt light and then straight after this the fuel light illuminates. I suspect this is a secondary problem but it worries me that it also could be connected.

I am still leaning to the ECM and feel the dash is a second problem, but thought I should run it by you guys first since you have probably cut your teeth on these cars. We do not see that many here in Australia 

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Caleb Technician
Mishawaka, Indiana
Caleb Default
 

The video is normal operation. Whoever is in charge of each warning lamp circuit is self testing the circuit at initial key on. I probably wont be as much help as some guys but ill put in my 2 cents. Im curious how you tested the powers and grounds to the ECM? Remember the only way the ECM can grd the relays( or any circuit the ECM is in charge of grounding for that matter) is by having good…

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Maurice Business Development Manager
Geebung, Australia
Maurice Default
 

The warning lights still concern me in the fact that in the video you see the seat belt light and the SRS light staying on, another time of turning on the ignition all the lights will go out including the SRS and Seat belt light and then all most straight away the fuel light illuminates. Yes thanks I know all about loading the circuits and how to carryout voltage drop tests. So regardless of…

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Scott Owner/Technician
Brantford, Ontario
Scott Default
 

If your power and grounds are ok and when you run the atm test on the asd if you vdrops are still out of spec ,ecm seems like a slam dunk .

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Maurice Business Development Manager
Geebung, Australia
Maurice Default
 

Thanks Scott I agree and I am about to call the customer with the news

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Caleb Technician
Mishawaka, Indiana
Caleb Default
 

Also not trying to be mean but does the ECM look "new" or like a reman anyway?? Theres a good chance that the customer never replaced the ECM an thats why he " no longer has" the old one.

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Maurice Business Development Manager
Geebung, Australia
Maurice Default
 

Sorry Caleb I should have said remanufactured ECM not a new one. He sourced this ECM from over your way and maybe he had to exchange his old one. I will be talking again with him today but he is like getting blood out of a stone when it comes to tell me the history of this car. I am now 100% convinced he has a faulty ECM. It is just that he lead me to believe nothing changed from when he fitted…

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