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No start xj

Jeepngdave

NAXJA Forum User
Location
Missouri
About two weeks ago I tried to start my 96 jeep cherokee with auto transmisssion and 4.0 6 cylinder motor and the starter would turn the engine over but it would not start. It ran fine the day before, when I tried to start it the next morning, no start. The same thing happened about a year ago and I ended up having to replace the ECM with one from a salvage yard and that cured the problem that time. I checked for spark at the distributer and coil and there is none. I hooked my code reader up and it says "no link" just like when the ECM died last year. So I buy a rebuilt ecm that is supposed to have a life time warrantee and when I install it in my jeep, no start, no fire from the distributer. So, I check the coil, coil wire, replace the distributer cap and rotor and and distributer pick up coil and perform the tests with my ohm meter to the cps and O2 sensors and every other sensor that my manual says that I can test without the engine running (it says that I can't check the map sensor, to take it to the dealer to have that checked) and everything tests good with the tester. I am getting 12 volts to pin # 1 and 11 volts to pin 15 at the ecm and 5 volts to the coil. So, I call the place that I bought the ecm from and the guy tells me that I must have a problem with my jeeps wiring harness since the code reader won't communicate with the ecm when I turn the key on. So, I unplug and check every electrical connection under the hood and clean the connectors with electrical contact cleaner. The connector beneath the ecm was very corroded inside and at both ends where the wires plug in but it still made no difference. Still turns over and no spark. The rotor turns when the engine is cranked and the engine has good compression so its not a broken timing chain. The place where I bought the ecm is supposed to be sending me a replacement but until it gets here, I am open to suguestions as to what I can try next. When I pulled a spark plug to do a compression test it was not wet from fuel so I am assuming that it is not getting fuel either as the plug was not wet after repeated starting attempts. I have never been able to hear the fuel pump switch on when I turn on the ignition key even when the jeep was new because its always been very quiet. I haven't investigated the fuel system because I've been concentrating on the electrical system to find out why the ignition doesn't fire. The wire going to the cps is good and it tests good with my ohm meter. All the fuses check good. I have no way to check the relays so I tried switching the ASD and fuel pump relays and still no start, no fire. I'm hoping that someone has had a similar experiance and can tell me what to try next.

Thanks,
jeepngdave
 
Just for a thought......mines an 88.....everything checked out except I got no spark from the coill to the dist.. I had voltage going in the ICM but no spark out.
Mine turned out to be the ignition control module. I didn,t find it till it finally quit running all together.
I dont know about the ICM on yours (1996)....mines a ICM/coil combo so replacing the module was the easy part on mine.
Hope this helps, as to something else to look for.
 
Hi,
Yes, I checked the cps with my ohm meter acording to the instructions in my repair manual and it checks ok acording to their refrence. The wires leading to the cps look good also and the trick of unplugging it and plugging it back in does not work, the engine turns over but still no spark. I tried replacing the camshaft position sensor in the distributer with a known good one and that didn't make any difference either.
 
Hi,
I have a digital meter. My service manual said to test the b and c terminals and the reading should indicate no resistance. Since the connector is not marked, I checked for resistance between the center and right terminal, then the center and left terminal and then between the left and right terminal and there was no resistance between any of the connections.
 
Hi,
Thanks for the links to the thread and website. They were VERY informative. I received the replacement ECm today and replaced it and I decided to replace the CPS at the same time and my jeep started the first try.
It's running a little rough and it may have an ignition miss (probably have something unplugged when I pulled all the connectors apart to clean them ) but at least I have something that I can work with now that its running again and I'm sure that I can sort out the rough running in short order now. Thank you again for the advice and information. The link is a gold mine! It goes into a lot more detail about diaginosing sensors than my repair manuals. :cheers: Many thanks,
Jeepngdave.
 
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