Strange Electrical Short - Looking for troubleshooting ideas

[Kyle Yaege]

Hi Everyone,

I have a 2009 JKU (Sahara trim), and I am having a very strange electrical issue that I need help trouble shooting.

I just wired in a new brake controller because I'm going to be towing a small travel trailer (roughly 3000 lbs) in the near future. As soon as I finished wiring in the controller, I started having an electrical short. Here are the symptoms:

• It only happens in the morning when it is cool (55-60) and wet (foggy/dewy) outside.
• When I turn the key from the "accessory" to "start" I hear a click (which I presume is the starter getting an initial jolt of electricity) and then the whole electrical system seems to short out (it blacks out all gauges, dome lights, clock, and stays dark).
• If I open and close the driver side door, it resets the entire electrical system (power immediately goes back to everything, clock resets to 12:00 etc..., but I don't get any error codes),
• After 2-3 "resets" by opening and closing the driver side door it turns right over and runs fine (no hesitation at all by the starter as far as I can tell).
• In the afternoons and early evening (when it is warmer and dryer outside) its jeep starts right up without any of these antics.

Trouble shooting so far: Because I had just concluded the brake controller install I started my trouble shooting by disconnecting the 12v power and brake controller power from the battery (because it is spliced into the low amperage brake signal coming from the switch above the break pedal, and the low amperage reverse signal driver rear light assembly, those connections remain in place.). I have also called the local jeep dealer to confirm that all recall service has been performed (it has), and confirmed that my unit is not covered by the starter switch recall that earlier models were subject to.

Operating theor(ies): My best guess at the moment is either that my remote start has finally failed (it has never worked properly) or that I bumped one of the connections (e.g. main power to the starter or to the remote start controller) when I was feeding the new wiring for the break controller under the jeep and the wet/cool morning is creating just enough moisture to ground out one of those connections and 2-3 resets creates enough of an arc to evaporate the moisture out. However, this theory doesn't explain why I seem to be able to reset the entire electrical system by opening and closing of the driver side door.

Other info: The same day that I installed the brake controller I also installed a transmission cooler, but do not believe that it is a contributing factor because all work occurred away from electrical connections except for temporary disconnection of the mass airflow and ambient temp sensors that have since been returned to their original locations/connections. The remote start on this jeep has never "worked" consistently, occasionally it will work but most of the time it just honks the horn at me.

Does anyone have alternative theories for where the problem might be?

 

[BLACKJKU]

Don't understand what the drivers door would have to do with anything, but sounds like a good place to start is the inspect clamps and cables. The click on starting sounds like a dirty connection possibly at the battery.

 

[Kyle Yaege]

Thanks BLACKJKU. The door reset is definitely the mystery factor (doesn't make any sense to me). Because I had to disconnect (and remove) the battery during my break controller install, the connections are freshly cleaned (they weren't all that dirty to begin with).

For the time being I will count this as a vote for my loose connection theory

 

[BLACKJKU]

Thanks BLACKJKU. The door reset is definitely the mystery factor (doesn't make any sense to me). Because I had to disconnect (and remove) the battery during my break controller install, the connections are freshly cleaned (they weren't all that dirty to begin with).

For the time being I will count this as a vote for my loose connection theory

But just because the clamps are clean and tight not everything is always good. Where the cables go into the terminals or clamps if there is alot of corrosion it can cause a problem.

Also when you mention about it being damp outside and having a problem, i've heard that is usually a ground problem. There are battery to engine ground, engine to body, and grounds in the harness. On my Jk one of the first things I did was to run ground from the neg terminal to the alternator case. To many grounds is never a bad thing.

Didn't you have to ground the brake controller ? Maybe that is where the problem if there were other grounds on the connection.