Engine light key trick

what is the trick to it? how do you do it. To get the code readout for your engine light.

wtf???

First off: what year is your XJ?

if it's a '97-up, this likely won't work. There's some anecdotal evidence to suggest that '97s with early software may allow you to do it, but this isn't proven by any means. For the rest of us in OBD-II-land, ain't gonna happen.

on obd 1 jeeps turn the key on-off-on off on than count the blinks on the check engine light

On my bros '01 XJ I know if you hold the trip reset in while you're...I believe turning the ignition on IIRC, it will enter into a diagnostic mode where all the gauges go from full back to zero position and all the cluster lights flash. Some have said this is how you can pull the codes too, but he's had a check engine light on while doing this before, and no codes appeared.

BigBlackHeep said:

On my bros '01 XJ I know if you hold the trip reset in while you're...I believe turning the ignition on IIRC, it will enter into a diagnostic mode where all the gauges go from full back to zero position and all the cluster lights flash. Some have said this is how you can pull the codes too, but he's had a check engine light on while doing this before, and no codes appeared.

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The test described above is a test of the cluster itself, including the gauges and the warning light circuitry. There was a transitional period (96 and maybe some 97) when they had OBD-II (using a scanner) but you still could get the OBD-I codes with the key trick. After that, there's no way to get codes without a scanner.

Are you talking about this?

http://www.go.jeep-xj.info/HowtoECUcodes.htm

Ken

Matthew Currie said:

The test described above is a test of the cluster itself, including the gauges and the warning light circuitry. There was a transitional period (96 and maybe some 97) when they had OBD-II (using a scanner) but you still could get the OBD-I codes with the key trick. After that, there's no way to get codes without a scanner.

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Ahh that explains why weren't ever able to make sense of any codes then. There weren't any.

Key on/off maybe 5 times and then leave on, and see if your check engine light flashes......5 flashes followed by a pause and 5 flashes means end of list, no codes present.....

That website will be helpful if you get any other codes. Flashes first number, then a pause, then the second number. Example of a code 22 or whatever, it would flash twice, then a longer pausem, then flash twice again.....then a longer pause, then flash 5 times, a longer pause, and then 5 times......and then it wouldn't flash anymore.

The transition year for the key clicky thing was '97. Early '97s you could do it, later ones you can't........

Ivan said:

The transition year for the key clicky thing was '97. Early '97s you could do it, later ones you can't........

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yep can vouch for 97's, my 97 Sport does it,
when doing this never fully turn the key off, move it into on position just before turning vehicle on, than back so there is no power to off position, but not so far back as to be able to remove the key... all you do for mine is:
key on/off on/off on/off leave in on position, and as stated wait for the CEL light to blink out its codes. Most seem to have the digi odometer which will also plainly show what code is being 'blinked' out... mine shows '24' '12' '55' while the CEL light blinks the corresponding.

with the Haynes Manual or maybe codes found online here it can be very helpful. Works also with 97 TJ's and my buddies 98 Dodge 1/2 ton aswell.