97v10mn

Hey guys, new to the forum, I have a 97 XJ that has been a work in progress, I went to start it yesterday and the guage cluster wouldn't work, IE the needles wouldn't move after the engine was running, no tach, wanted to stall if you put it in gear. My buddy pulled the connectors off the ecm to reset it, the gauges worked but it wouldn't idle, thinking it had to relearn to run we drove it for about ten minutes, seem to run ok but did stall once, had to keep on the fuel or it would stall. Early today it would start and idle but missed horribly, blew black smoke, wouldn't idle for crap, miss stayed with rpms. So I shut it down pulled connectors off ECM, cleaned IAC, pulled terminals off battery. Still no gauges, so I gave up for a few hours, went out early tonight, fired up and idled, had a high idle and a slight miss, it idled that way for about ten minutes then finally died. Pulled the dash apart to check connectors, they look like they had been done before as they still had die electric grease on them. Guages still do not work ie volts dont go up when running nor does oil pressure and no tach, but I did notice that even with the jeep running the dome lights were dim, I checked the volts at the battery and they were 13.9 running and 12 with the jeep off. It has a new battery so I'm not sure why the lights would be dim, the only thing I've changed this week has been replacing the TCU and battery terminal ends? The jeep ran fine before yesterday, it had a slight miss when cold but ran fine, had great power, good throttle response. It has had the ECU replaced before when my brother had it, could it be the wrong one or could it have gone bad? It was a junk yard one iirc. I have done the cluster test where you held in the reset button, the needles all moved, and its not throwing a code either. It will run if you give it throttle but it still dies if you put it in gear. Leaning towards ECM, any suggestions guys? Sorry for the long first post.

Radi

You sure the grounds between the battery, chassis, engine, etc are all in good shape?
The dim lights point to an electrical problem somewhere, which might be affecting the ECU.

97v10mn

Honestly I did not, I was really confused at this point and was scatter brained. I'm new to Cherokees, can you tell me where all the grounding points are on an Xj? I'm assuming theres two or three running to the block then a few running to the body? I know theres the one that runs from the negitive terminal to the body, is there any major ones that I should look at?

Radi

Grab a digital voltmeter, set it to the lowest DC voltage scale you have and check for voltage differential between battery (-) and various points on the block, chassis, etc.
(negative test lead on battery (-), probe block, ECU ground, etc with positive test lead). If you have anything more than a few millivolts, perhaps 1/2 of one volt at most, the ground to that area is suspect.
Do it with the engine running and headlights on so some current is flowing through the grounds.

97v10mn

Ok, I have a digital mulitmeter that has an auto range function, IDK if that makes a diffrence or not, but I will try that tomorrow, hopefully I can get her fixed up, I would like to drive this thing haha.

97v10mn

Also im not sure how it will act tomorrow, I doubt I will be able to keep it running and check the grounds at the same time, hopefully ill get lucky and have a bad ground and it'll take care of the other issues

97v10mn

Update: I cleaned the grounds for the battery that runs to the fender, also the ground strap that runs from the back of the head to the body, I had to splice on a new ring terminal as the strap was about ripped off from the original one, On a whim I unhooked the TCM I just put in and it started up and idled fine, all gauges worked, I left it set there and run for about half hour, had a slight miss but I think it needs a tune up. I re-hooked the TCM just for a minute and the gauges stopped working, so I'm thinking that there's a short in the wiring as I tried the original TCM and it did the same thing, I shut it off and restarted it and she fired right up with all gauges working, So I'm thinking of running a separate ground wire from the TCM connector to the battery just to make sure it grounds itself. I took it for a test drive with the TCM unhooked and it ran fine except it had a miss and pop under moderate throttle, almost like what the tps did on my TJ before I replaced it, I'm going to unhook it and see how it runs. I'm going to do a tune up next time I'm home, plugs, wires, cap and rotor as I'm not sure when it was last done plus it's sat for almost a year before I got it.