Evil Gremlins

I've hit a roadblock and am about to give up and turn the XJ into a mechanic. I have a '97 4.0, Auto. It wouldn't start, so with 171k on the clock, I gave it a tune up. Coil, distributor, rotor, plugs and wires (no el-cheapo parts either).

That didn't work, and I was getting pressure at the rail (solid squirt at the valve), so I assumed CKP. After reading all the horror stories on aftermarket units, I bought the Mopar crank position sensor... still no dice.

I got a fuel pressure gauge and lo-and-behold, bad fuel pump (so much for the accuracy of the squirt test). So, I swapped in a Delphi unit. At this point, I'm over $400 into trying to get the darn thing to run.

It finally runs and now no gears (OD only). I have a P1689 code throwing. No gauges (intermittently the fuel, water temp and voltage works, but never the tach or speedo), CEL and "Airbag" light. So, also sitting in my driveway is a '98. The PCM in the engine bay has the same MOPAR part number on it, so I swap 'em. The 97 computer runs the 98 just fine and the 98 throws the same code in the 97, so it's not the PCM. Chassis grounds by the battery, near the PCM, and engine to chassis are all in what appears to be good shape.

I'm at my wits end and I'm not even sure how to start chasing electrical gremlins across a twenty-year-old wiring harness. Could it be a bad fuel pump itself? This thing wasn't the cheapest, but it wasn't MOPAR either. I'm not used to requiring dealer parts as a prior Chevy guy, everything I bought just worked for those cars/trucks.

I'm a bit past frustrated, so I'm likely just venting and am going to hand it over to a mechanic on Monday. Then I'll be into the repair for as much as the vehicle costs... :doh:

The symptoms point to an electrical issue. Possible causes: open CCD BUS (+) circuit between modules, TCM not powered up, faulty TCM or PCM. Unplug the horn relay, the airbag clock spring at the steering wheel, and unplug the the TCM. See if the codes clear up. Drive with the TCM disconnected and shift using the shift lever. If all the gears function, the transmission should be OK.

You have removed, inspected, tested for continuity, and firmly re-connected all the ground points, or they just appear to be in good shape ? Don't forget the grounds at the coil which are for the TCM. Have you tested the transmission shift solenoids ?

A used TCM should be inexpensive if you want to diagnose by swapping parts.

^ This guy. Awesome. Thanks Tim, you were spot on. When I put the coil in, I missed one of the several grounds that are grounded there. I beat my head all day swapping parts, pulling codes... so simple. Thank you for saving me an embarrassing trip to a mechanic.