99-01 ? jeep cherokee. Posting for a friend who wants to rid his brothers jeep of issues. It has a constant check engine light on. Tried key on-off-on-off-on....................but the engine light does nothing but stay constant. Is it being done wrong? Ideas?

99-01 ? jeep cherokee. Posting for a friend who wants to rid his brothers jeep of issues. It has a constant check engine light on. Tried key on-off-on-off-on....................but the engine light does nothing but stay constant. Is it being done wrong? Ideas?

When you turn the key on-off-on-off-on watch the odometer and you will get an error code. The light should then shut off until the problem occurs again.

76455firebird is right, If the jeep is equipped with a digital odometer then your error codes will come up on the odometer.

Thanks for the Info!!!

76455firebird is right, If the jeep is equipped with a digital odometer then your error codes will come up on the odometer.
I don't think that will work as it is new enough that it has an OBD II system and you may have to get a scan tool to read the codes. Tool cost is under $50.00

All Jeeps (well grand Cherokees) have the built in code extractor, On non-digital Ocometer you wil have to count the # of times the CHECK ENGINE LIGHT flashes and on Digital Odometers the code will pop up in the Odometer. That goes for OBD II and earlier.

You know? I've never been able to get this to work.
I have three jeeps, a 96 JGC, a 89 LTD and a 90 sport....and I have never been able to get anything to flash...on any of them...ever!

If after I do the key thing, and there is no code to display, will it do anything at all?

Or is there some trick I don't know about?

Ed
web/gadget guru

Yes you will at least get a code 55...

When you turn the key to the ON Position (ON Position, the furthest forward the key will move without cranking the engine), Does you check engine light come on?

to get the codes....
Turn the Key ON, then OFF, then ON, then OFF, then ON - leave it in the ON position this time, the CHECK ENGINE light will begin to flash. Count the number of flashes. It will flash out double digit codes, There will be a SHORT pause between Digits and a LONG pause between each code.

Example:
flash pause flash flash 1 pause 2 - Code 12
pause pause pause pause pause pause
flash flash flash flash flash pause flash flash flash flash flash 5 pause 5 - code 55


and on Jeeps equipped with Digital Odometer, the code will apear in the odometer, P????


Make sure you are turning the key all the way forward but not as far as to engage the starter.

Everything worked great for my friend. Only hitch was he had to press the tripometer reset while he did the on off thing. I forget the code he said....23 or 24... it was the "Intake air temp" sensor. I didn't hear the outcome yet but I'm sure it was the connector or sensor itself.

Thanks again