help check engine light
10-06-2010, 02:37 PM
#1
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Year: 1990
Model: Cherokee
Engine: V6
help check engine light
check engine light wont work , dose nit come on at all , failed smog , i check fuse and did the disconect battrey for and hr but it didnt reset it . i have a 1990 jeep cherokee , 6cyl 4 wheel drive .
can anyone help me i cant register car till i get that fixed i might add my blinkers and radio and air /heat and horn went out all at the same time
ty bcingu
can anyone help me i cant register car till i get that fixed i might add my blinkers and radio and air /heat and horn went out all at the same time
ty bcingu
Last edited by bcingu; 10-06-2010 at 02:45 PM.
10-06-2010, 04:14 PM
#3
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Year: 1987
Engine: Check
If its not a bulb or fuse, which is really, really easy to figure out, its your ECU.
If the truck doesn't toss a CEL when the truck is first turned on, the fuses are good and so is the bulb, 99% of the time its a bad or going bad ECU (aka PCM, etc).
If the truck doesn't toss a CEL when the truck is first turned on, the fuses are good and so is the bulb, 99% of the time its a bad or going bad ECU (aka PCM, etc).
10-06-2010, 10:07 PM
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Year: 1990
Model: Cherokee
Engine: V6
thank u very much for the info its not the bulb but i dont know what a ECU is can u tell me so i can check it . i very much apprecate u taking the time to help me .
bcingu
bcingu
10-07-2010, 10:40 AM
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Year: 1987
Engine: Check
I'm not sure about these trucks specifically but I do know some OBD-I cars DO indeed have CELs. Someone with more in depth knowledge of Jeeps specifically needs to cover that. I'm more of a general knowledge kinda guy.
As for the ECU...
The ECU (engine control unit) is the car's computer. Its what runs the show, electronically.
It shouldn't be hard to check. Just open it up and look for leaky caps, and smell it...which sounds weird. If you smell a fishy smell, its likely toast. You can try finding someone with a known good ECU and swap them out. Check to see if your truck is OK when the other ECU is in it.
That is, if your truck does indeed have a CEL...
As for the ECU...
The ECU (engine control unit) is the car's computer. Its what runs the show, electronically.
It shouldn't be hard to check. Just open it up and look for leaky caps, and smell it...which sounds weird. If you smell a fishy smell, its likely toast. You can try finding someone with a known good ECU and swap them out. Check to see if your truck is OK when the other ECU is in it.
That is, if your truck does indeed have a CEL...
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10-11-2010, 02:44 PM
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Year: 1987
Engine: Check
You'll have to remove the ECU from the truck itself and open it up, sorry, I probably wasn't very clear with some of my information.
If you do remove the ECU make sure you lable where each plug came out. If you can use tape on each plug, label the first one you remove #1, and stick a #1 next to the port you removed it from. Move down the line til all are marked.
Most vehicles are set up so only the correct plug fits in the correct port, but I've never pulled an ECU on a Jeep, so its best to cover all bases before just assuming.
Once out, you'll either need to swap in a different ECU you KNOW works (say, from a friend or neighbor's truck), or open it up and inspect manually.
Again, you'll be smelling for a fishy smell, and you'll be looking for leaking capacitors, or what looks like burnt computer parts.
If you do remove the ECU make sure you lable where each plug came out. If you can use tape on each plug, label the first one you remove #1, and stick a #1 next to the port you removed it from. Move down the line til all are marked.
Most vehicles are set up so only the correct plug fits in the correct port, but I've never pulled an ECU on a Jeep, so its best to cover all bases before just assuming.
Once out, you'll either need to swap in a different ECU you KNOW works (say, from a friend or neighbor's truck), or open it up and inspect manually.
Again, you'll be smelling for a fishy smell, and you'll be looking for leaking capacitors, or what looks like burnt computer parts.
10-11-2010, 02:54 PM
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Year: 1995
Model: Grand Cherokee
Engine: 4.0 with all of the noise and clatter
A shop I used to work at years ago had a truck that had a check engine light spot on the dash, but nothing was ever wired from the factory to light a bulb. It would not pass smog for the very same reason as your Cherokee, the check engine light would not light during the bulb check. We researched this truck for weeks, combing over wiring diagrams, talking to the dealer with the VIN, nothing was helping. The truck would pass the sniffer and every other part of the inspection except the stupid check engine light. We got to thinking and noticed the oil light would come on with the key and shut off once there was oil pressure in just a few seconds. We ended up wiring a bulb for the check engine light to the oil light. It acted like it would as if it was from the factory, it came on with the key and shut off after a few seconds just like it should. It was enough to fool the guy doing the smog inspection and the truck passed.
10-11-2010, 02:56 PM
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Year: 1987
Engine: Check
A shop I used to work at years ago had a truck that had a check engine light spot on the dash, but nothing was ever wired from the factory to light a bulb. It would not pass smog for the very same reason as your Cherokee, the check engine light would not light during the bulb check. We researched this truck for weeks, combing over wiring diagrams, talking to the dealer with the VIN, nothing was helping. The truck would pass the sniffer and every other part of the inspection except the stupid check engine light. We got to thinking and noticed the oil light would come on with the key and shut off once there was oil pressure in just a few seconds. We ended up wiring a bulb for the check engine light to the oil light. It acted like it would as if it was from the factory, it came on with the key and shut off after a few seconds just like it should. It was enough to fool the guy doing the smog inspection and the truck passed.
But I don't think this'll help the OP. She said she changed the bulb, so it sounds like the bulb is in place...
10-11-2010, 06:18 PM
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Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
my 89 does not have one either did not come with one either good luck the codes caN can only be gotten with a special scanner have never seen or heard of any body with one