I have a 1999 Jeep XJ, stock, but it has a brake controller installed recently.

Just got back from a camping trip where I towed a camper for an hour with a 7pin and brake controller. Parked the trailer in the storage lot, unplugged the jeep, moved it, and packed the trailer away. When I went back to the jeep it wouldn't start. It won't turn over or make any noise other than what sounds and feels like the "cigar" relay clicking in the passenger fuse/relay box. Tried jumping it with no change.

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I took the battery to AutoZone and they said it was fine (battery is from January 2022). I got my tools and tested it myself and it was ~13.5 on the multimeter. Next I took the starter in and AutoZone said it was also fine and was activating.

Any suggestions on what to try next?

I thought maybe the alternator, but the battery is charged and it should at least start or turn over.

Headlights, radio, air, etc all work fine.
Fuses are fine.

 

On my '99 I had loose crankshaft position sensor bolts, which prevented it from turning over. After tightening them, it fixed the issue. Worth checking out, since they're easily accessible with a 6" extension and a socket u-joint. The CPS is located on the top right of the bell housing, when looking at it from the rear.

 

Your starter wouldn't even crank? (Mine isn't)

 

Yeah it was really frustrating, for a while it would randomly happen. I would drive somewhere, park, and when I went back to jeep it wouldn't even try to crank. Radio, headlights, all that worked just fine. One day after whipping it, it died right when I was rolling into my driveway. I looked under the jeep and my CPS had fallen out and was hanging by the wire. Only reason I realized that was the issue. Got new bolts, put it back in, and no issues ever since. The connection to the ECM is really easy to access, its in the back right of your engine bay, probably going over the fuel rail if I remember correctly. You could start just by unplugging the connector and testing the CPS sensor. If its bad, replace it. If its good, check to make sure its bolted in tight. Here's a link to the YouTube video I used to learn.

 

CPS was tight.

Turned out to be the ignition switch actuator. What looks like a sleeve had broken off

 

And for future reference for people reading this thread: how did you find that?

 

I had to take it in to the shop