No start - would rather diagnose than throw more parts at it!

Last night my 96 XJ (4.0) quit while driving down the road. It was runnning fine, and just quit out of the blue. No recent swimming expeditions. It has not been worked on for a few weeks, and even then was just a lift and tires. It did lose the fuel gauge (reads empty with low fuel light even when completely full) a couple weeks ago. I offer that in case it's relevant to troubleshooting.

I tried a couple things including pulling the battery ground, and could not get it to restart. Went and got the flatbed to haul it home and got into it this morning. It does not show any codes or check engine light. The Gen light does come on sometimes when cranking.

Used old_man's "How to Troubleshoot a No Start XJ" as a guide. Have good crank, fuel at the Schrader valve, but no spark. Winched it onto flatbed last night, so put battery on a charger to make sure it had good voltage, still no spark. Fiddled with a half dozen electrical connectors, still no spark. Changed CPS. Still no spark.

Now what? The listed choices were "bad coil/ignition module, a bad ECU, or a bad ignition switch".

Are there easy tests for coil?

What does the ECU look like? I unplugged/replugged a few things under the dash, but not sure what I'm looking at.

Any easy tests for the ignition switch? Any other ideas? I can start throwing more parts at it, or load it back on the trailer and haul it to a pro but I'd rather do it myself.

It wouldn't hurt to check the AutoShutDown relay in the PDC.

Slo-Sho said:

It wouldn't hurt to check the AutoShutDown relay in the PDC.

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Excuse my ignorance, but the what in the which?

PlainWhiteXJ said:

Excuse my ignorance, but the what in the which?

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Power Distribution Center

The black plastic box - PDC - under the hood to the front and left of the coolant bottle as you face the engine bay. Lid has a latch on the front side.

If you have a short somewhere that has blown the ASD fuse (it's a mini blade, 30A, left and 2nd in from the front, iirc), that will cause no spark. Also, same thing if the ASD relay is bad (in the same PDC, but farther back - check the inside top of the lid for location diagram).

Thanks Guys!

It was a blown fuse. Now I just get to figure out why it blew, but in the mean time I have a running truck.