Joe34

Hi,
1999 Jeep Grand Cherokee 4.0 engine.
Cannot get check engine light to go off.
Took it to Autozone and Orileys to scan codes no codes show up.
Tried the disconect batt. cable deal no luck and on off ignition 3
times and on off on headlight switch, still on.
Took it to Jeep dealer, said engine cooling fan motor was drawing to many amps.
I replaced the complete unit fan motor and shroud.
Took back to Jeep dealer to clear, now showed fault in fan relay.
Replaced fan relay under right front headlamp, and checked all fuses, and
fan relay in fuse block under hood.
Took back to Jeep dealer to clear, said no codes showed up, would have
to have tech man check wiring, at $100.00 an hour.
Don't think so!
Any other ideas? Thanks for any help.

5-90

Check the wiring yourself? If you can score an FSM, that will help you. (As a temporary measure, PM me your address and your filesize limit by your email provider, and I can come up with a few things to help you.) Visually checking wiring ALWAYS takes a while, which is why you should do as much of it yourself as possible. You can usually narrow down the repair bill rather sharply that way, since most wiring faults are visually obvious (even to the neophyte.)

Joe34

Traced wire from cooling fan relay, to PCM,
all OK.
Still cannot get light to go out?

Trxgedy

I kind of had this problem... my check engine light kept coming on and my jeep would over heat. When I would go get the codes read they said it was my fan sensor relay... well I replaced this 3 times. I have a wiring problem where the fan sensor relay gets power but won't send a signal to the fan to click on. So I wired the fan straight so its always on and my check engine light just went off.

Good ol WJs

5-90

Bear in mind that, even with OBD-II, a DTC will only tell you where to start looking. It's not going to give with the actual fault, although everyone seems to think so.

A fault indicated by an OBD-I or OBD-II DTC means something in that circuit has failed, not necessarily the item itself. If you don't investigate, and waste money by throwing parts at it, you deserve to. An hour spend troubleshooting and inspecting is ALWAYS cheaper than merely throwing parts and something and hoping to fix it under the "Million Monkeys Principle."

SeriousOffroad

Disconnect the pos. and neg. leads from the battery and touch them together for a few seconds.

Joe34

I have tried,touching the cables together, and also
leaving them off for 10 min. then 30 min.No luck.