No Spark No Fuel No Start! 93 XJ Help!

1993 Cherokee 4.0L . I think I've tried and checked everything. Power everywhere. Disarmed the factory security. No blown fuses of the big 40a one either. Cranks like crazy but no fire. No spark or fuel delivery. Possibly someone criss crossed the jumpers trying to start it with dead battery so searched for fusible links possibly burned but can't really find any. Only CEL code, using the blink system is 12, battery recently disco'd. Then 2 5's. All clear. Did replace CPS, but nothing. Mine is a Calif.emiss. A/T, with security. Trying to find a ECU to try. Did try one without security and nothing. Even with the ECU disco'd , it cranks all the same. No spark no fuel. Fuel pump does engage when you jump 30 and 87 with the relay removed. My ECU is a 56027285. I guess Murphy's Law would prevail if the criss cross jump cables burned the ECU box to save the 40amp fuse in the relay box. Can a scan tool reset/reboot a 93 ECU? I'm about to buy a used ECU, so someone stop me. Thanks for any help.. David in Calif. 714 751 2464 or 865 2464 if need be.

IF you are getting CEL codes from the ECU, the ECU may be OK. There is a relay or two on HOs that can kill fuel and spark, I forgot their names.

Try swapping the ASD relay with the AC relay.

Just a thought.

A scan tool cannot reset or reboot a 93 ecu any different than disconnecting the battery or unplugging the ecu does.

The Dark Blue wire coming out of your security module has to have current, it is the actuator current for the ASD relay. The Dark Blue and Yellow wire to your ASD relay has to have ground, it grounds the ASD (and fuel) relay through the PCM.

Various sensor (problems) will shut down the ASD actuator ground at the PCM, the security module will interrupt the ASD + actuator feed.

The Dark Green and orange wire is the main feed for your coil, injectors and alternator. It is the 87 pin on the ASD relay. The 30 pin is main power *in* to the ASD relay, fused Red Black and *I beleive* (assume) only hot when the ignition is in run or start.

I think your security is much the same as my 96 (export), it isn't in the PCM, it is a separate module, mine is by the hump in front of the shifter console.

Digger87xj said:

Try swapping the ASD relay with the AC relay.

Just a thought.

A scan tool cannot reset or reboot a 93 ecu any different than disconnecting the battery or unplugging the ecu does.

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Thanks Digger, have done that with no progress. This ASD module sounds interesting, no idea where it is, one reader said on his 96 its on the tranny hump? Can you jump it like I did the fuel pump, just to hear it run? Maybe 87 and 30 . I'm pretty sure I have the security disengaged, 2 fuses out, no flashing lites when battery on and off etc. Thanks again. David in Ca.

Bandonbound said:

Thanks Digger, have done that with no progress. This ASD module sounds interesting, no idea where it is, one reader said on his 96 its on the tranny hump? Can you jump it like I did the fuel pump, just to hear it run? Maybe 87 and 30 . I'm pretty sure I have the security disengaged, 2 fuses out, no flashing lites when battery on and off etc. Thanks again. David in Ca.

Click to expand...

I don't know exactly where the security module is on your 93 but, but I'm pretty darned sure it has a ASD cutout built in, the dark blue wire coming out of the security module has to have power. Pulling the fuses is unlikely to be helpful.

The ASD relay is in the PDC, should say where on the inside of the cover or in your operators manual. ASD stands for auto shutdown relay. You can usually feel it work (the click) with the tip of your finger. Or you can volt test at the coil or the alternator (dark green and orange wire).

Other things can open the ASD, like a necessary sensor signal missing during cranking, CPS and others.

No Spark No Fuel No start 93 XJ Update

Tried a donor ECU yesterday, not the exact one but close. A 117 box. Doesn't have the security mode. BUT, using this one I did get a dash CEL symbol and was able to use the key method and get CEL codes. Only 1 2 as I said previously but using my original 285 ECU box, no CEL. Does this narrow it down to the ECU box? This ASD module sounds promising as I do not have 12v at the coil. Thanks to all. David in Ca. 714 751 2464 if need be.