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-   -   99 XJ, No Bus P1694, p1686 starts, misses, dies (https://www.cherokeeforum.com/f2/99-xj-no-bus-p1694-p1686-starts-misses-dies-242063/)

Jeepsinker 02-04-2018 02:28 PM

99 XJ, No Bus P1694, p1686 starts, misses, dies
 
Hey guys, got a deal on this XJ. 2wd, 4.0, AW4. Bought it sight unseen figuring the crank sensor went out buy that isn't the issue.
I've followed the thread on the 97 XJ with the bus failure and done all the testing there.

I've got 1.5-2 volts fluctuating on the dlc connector pins, even with all the modules unplugged except the pcm and cluster. I get 122 ohms across the pins with battery disconnected and key off.

I did test the wires from pins 28 and 30 to pins 3 and 5 on the dlc connector and found good continuity @ 1.5 ohms.
Testing the pcm pins #28 & 30 all I get is open circuit. I am unable to get anywhere near 2.5 volts at the dlc connector no matter what I do, and if I've read everything right, it appears the the terminating resistors in my pcm have burned and opened, but I can't figure out how I would have any voltage whatsoever at the dlc connector, much less how the vehicle would run at all if that was the case.

Also of note: I have checked reference voltages at the engine sensors and got 5.1 volts across the board, which would suggest that the pcm is not bad, Right?
I'm assuming the Skim bus failure and pcm bus failure are directly related, as they run off the same bus, and I'm sure the Skim bus failure is why it only runs for three seconds before shutting down.

What am I missing here?

Jeepsinker 02-07-2018 05:30 PM

Well, I appreciate all the help and second opinions. I'll be ordering a new pcm tonight.


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