96 4.0 5 spd 4x4 ecm cutting out
04-13-2017, 07:37 AM
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96 4.0 5 spd 4x4 ecm cutting out
My 1996 4.0 5 speed with 237k miles started having issues a few weeks ago. It seems that the ECM is momentarily cutting out for about 1/2 a second. The reason I say the ECM is I had my cat removed several years back and the check engine light is now always on. When the problem occurs, the check engine light clears for several drive cycles after that. Nothing else electric seems to be affected, lights, radio, gauges, etc. This has happened in different circumstances but seems to happen more often when accelerating. Is there a common failure point that I should look at for this problem? ECM ground connection, etc.
04-16-2017, 07:47 AM
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
ECM is the LAST place I would suspect.
04-16-2017, 09:56 AM
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Year: 1998 Classic (I'll get it running soon....) and 02 Grand
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Engine: 4.0
Agreed!
The ECM is a mysterious black box, known to possess amazing powers, exercising control over everything on the vehicle, and darkly suspected of controlling alternate universes, influencing foreign elections, and, in some cases, torturing puppies in the dark of night, as well.
Being mysterious, it is automatically the first suspect when anything happens that is not understood.
It's rarely the problem. The only two failure modes I know of are poor connections (ground as the first suspect) and internal failure. Poor connections can be anywhere in the harness that leads to it, the ground is under the coil, and, and internal failures require replacement.
Your problem is much more likely to be elsewhere. Spend your time troubleshooting other things.
Put the cat back in and your problem will probably be solved.
The ECM is a mysterious black box, known to possess amazing powers, exercising control over everything on the vehicle, and darkly suspected of controlling alternate universes, influencing foreign elections, and, in some cases, torturing puppies in the dark of night, as well.
Being mysterious, it is automatically the first suspect when anything happens that is not understood.
It's rarely the problem. The only two failure modes I know of are poor connections (ground as the first suspect) and internal failure. Poor connections can be anywhere in the harness that leads to it, the ground is under the coil, and, and internal failures require replacement.
Your problem is much more likely to be elsewhere. Spend your time troubleshooting other things.
Put the cat back in and your problem will probably be solved.
07-08-2017, 06:33 AM
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Fixed!
So for anyone that may have the same problem or similar issue I'm calling my issue fixed. First, I must say that I did not reinstall my cat as this was not related to the problem. Turns out the ignition switch was the cause. The run signal to the ECM from the ignition switch was only reading about 11.5 VDC at the ECM. The switch itself had high resistance and the connector had signs of overheating. New switch and repaired connector brought the voltage up to 12.6 VDC at the ECM. I've had no more problems since then.
07-08-2017, 08:02 AM
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Year: 1990
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Thanks.
