XJOZ

Some what of repeat I just posted in the codes sticky. Wasn't sure if I'd get read there so......

Threw a code last night on the way home. Turned it off and restarted it no problem no code.

Went to start it and it won't start..no code. No check engine light. Did the key trick in park and neutral with the emergency brake on. No luck as nothing is flashing.

Ideas? Possibly the ECM is bad as it should at least light up if no codes(I am unsure if it should flash at least something if no code???)

I'm 700miles from home.....

salad

1991 with the 4.0?

Are your battery cables good? Blaming the ECM for a no start is a pretty big leap on an vehicle where everything is dependent on good wiring and grounds.

Go through here and complete 1, 3, and 5: https://www.cherokeeforum.com/f51/cr...x-tips-153657/ it's geared to the previous generation but most of the knowledge is the same.

BimmerJeeper

It's too bad you cleared the code.
The expensive and brilliant engineering of OBD2 was trying to tell you what is wrong.
Now, you'll need to wait for the code.

tjwalker

Do you mean the engine turns over but doesn't start? Or the engine doesn't even turn over? If it doesn't turn over, start with the basics including battery and battery cables and grounds.

1991 is OBDI. Using the below technique, you should get at least a code 55 (end of codes) if no trouble codes are present. Even an old code should still be there as a "stored code".

Retrieving OBD codes on the Jeep Cherokee (XJ)
OBD1 Models: 1991-1995
1) Start engine (if possible). Move transmission shift lever
through all positions, ending in Park. Turn A/C switch on and then off
(if equipped).
2) Turn engine off. Without starting engine again, turn
ignition on, off, on, off and on within 5 seconds. Record 2-digit
fault codes as displayed by flashing MIL.
3) For example, fault code 23 is displayed as flash, flash,
4-second pause, flash, flash, flash. After a slightly longer pause,
other codes stored are displayed in numerical order. When MIL begins
to flash fault codes, it cannot be stopped. Start over if count is
lost.
NOTE: A "5-5" will always occur to signal the end of the sequence. Some will flash the "1-2" code indicating a recent battery disconnect even if you haven't done it. Ignore these two codes, and mark down all others.

XJOZ

Yes it's a 91 and not obd 2. I wish it was as a have a scanner I use for my vette. They typically store current and historical codes in a none volatile ram. Removing the power just reboots it in case there has been some voltage or current fluctuation that can make any computers program crash.
The indicator for me is that if the ECM was functioning I'd expect to get code or something from the check engine light. If that's nit functioning it is part of the ECM caused by a malfunction of another component? Possibly. With out the codes reading one could chase and replace all systems and sensors to no effect.
The epoxy is all cracked and crazed in the box. I can see a few caps that look like they have over heated. It looks pretty used up in there.
The Haynes manual goes through how to extract codes for various models. On the 91 4l they don't state there is a code that flashes to state you are going into that mode or has run through andvstatesvannall is ok code as it does on at least oe other model. I find that odd as ivebworked on many obd1 cars BMW,vette, Saturn, Toyota, etcetc that have all displayed some code to let you know it is functioning. I've been working on cars since 77. And found the obds greatbasblong as the ECM is working. When they fail it's expected as its in a hostile environment for any computer. I like bmwbas they typically place them in a box within the firewall andvarentbsubject to so much heat.
So with no codes I'll verify the bulb us working and get a new one. Dealership can get me one fr,get this, $1,000. There is only one left in Canada andvatbthat orice. I'll order a new if the bulb is good.

However if someone can verify that. There should be some signal thatbhebecm displays even if there are no current code that would be great.