Mystery Power

[Sting-Gray Neutral Pres.]

I had power on my diesel when I didn't expect any and am scratching my head as to where it came from. Here's what happened.

1. Disconnect main battery ground at post (only, no wire separations) and isolate. Disconnect both front and rear body grounds on the passenger side of the engine bay and isolate. Remove PCM. Sat for a few days while I did stuff, reconnected PCM, and first touch of the main battery ground to the post sparked and fired up systems just as expected.

2. Power cycle truck, repeat everything in step 1 except time the truck was "dead" was very short. About 5 min after disconnecting everything I plug in the PCM, and with all of the 3 aforementioned grounds fully disconnected and isolated.....the hum of the DEF return pump kicks on. Where the heck is power coming from? There has to be some other ground that is still connecting the Aux battery, or maybe a capacitor is in the system?

I want to figure this out because electrically, "dead" truly needs to mean dead.

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[sharpsicle]

Good question, but I don't think it needs to be chased down too far. I would just disconnect the AUX ground cable itself at the main battery terminal. With that disconnected, and the clamp off the main terminal, you've removed every possible grounding path to a battery. Much easier than trying to hunt down various body grounds.

 

[Sting-Gray Neutral Pres.]

Thanks, I think that solution sounds logical and I'll do that next time.

 

[Free2roam]

And to think I was thinking that there was some kind of trick the Jeep put in there. Punch buttons disconnect power. Reconnect punch buttons. Lock unlock then start. And all of a sudden I've got the mystery power. 500hp and 900 ft pounds of torque. Guess not

 

[Sting-Gray Neutral Pres.]

We're still trying to find Plaid Mode for this flying brick, its buried in a hidden menu somewhere!

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