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1997 TJ Start Issues

Old 12-08-2018, 04:46 PM
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Year: 1991 - 1996 - 1998
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Default 1997 TJ Start Issues

This is a RHD postal Jeep. I have had zero problems with it until my son turned 16 a few days ago. He took it out for his first taste of freedom, and it let him know exactly what driving a Jeep is all about. Driving down the road and it just shut off without warning or CEL. No codes to speak of. The problem is crank - no start. After a long period of time it will start and run great for about 5 minutes then shut down. After it shuts down, no spark (verified with spark checker), and no fuel pressure Verified with gauge on rail). I swapped out the crankshaft position sensor, no joy. Verified with a multimeter that the crankshaft and camshaft position sensors are functioning normally while cranking. Oddly, it will try to start in neutral. It stumbles a few times, then shuts down. This does not happen in park. In drive, reverse, or 1-2 it will not crank. Can anyone explain this? It has a different NSS installed than what Rock Auto or any of the other stores say it is supposed to be. I will add photos shortly. All the grounds that I can find have been refreshed. ASD relay has been swapped out.
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Old 12-08-2018, 05:11 PM
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NSS Plug

NSS

This NSS does not appear to be the same as what can be found at Rock Auto or the other stores. Does anyone know the part number?
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Old 12-08-2018, 08:33 PM
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Do you get fuel pressure on initialization?

Just key on before cranking?
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Old 12-08-2018, 09:23 PM
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Thanks for the look cruiser.
No fuel pressure with the key to ON. After looking over the wiring diagrams, I am starting to think I have a ground problem. When the Jeep was running, the OBDII would connect to the code reader; after it went to no-start, the OBDII would not connect. The ground G105 is for the PCM to operate the OBDII. It also is the PCM ground for the crankshaft and camshaft sensors. I did not have a good ground on the wiring for the two sensors while cranking over the engine, but I did have nearly 5V on both signal and reference. I found it strange that both the signal wire and reference wire read exactly the same as the engine cranked. On my XJ, the signal was a pulse and the reference was 5V steady as soon as you turned the key to ON. Plan of the day for tomorrow is to find G105; I have the FSM ground diagram...wish me luck. I'll keep you posted. Still not sure about it trying to start in neutral...
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Old 12-09-2018, 05:39 PM
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Problem solved. The PCM was bad. I slaved in a PCM from a 1998 XJ and it runs like a champ. It does have a CEL because of the different transmission. Verified the no-start on the other vehicle.
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Old 12-09-2018, 05:45 PM
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Nice work.
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Old 12-09-2018, 08:04 PM
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Thank you sir. I was sure it was a bad ground or splice, but pulling on wires and moving the harnesses was getting me nowhere. Desperation makes you do crazy things like swap PCM. This time it paid off.
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