Damn Gremlins - JKowners.com : Jeep Wrangler JK Forum
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post #1 of 3 Old 09-10-2010, 10:12 AM Thread Starter
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Damn Gremlins

It it's driving me nuts.

So the JK has been acting funny electrically and it's getting worse. It started that the seat belt light would flash and chime once in a while, eh I can live with that. Then it grew to the seat belt light coming on when I press the brakes once in a great while. Now it sometimes will flash with the flashers as well (when it's acting up). It's random but once it starts and stays around for a while then goes away when I bust out the multi meter.

Here's the kicker. When it's acting up the flashers go fast indicating a bulb is out so I checked, rear flashers don't work when it happens but front do. So I checked brakes, same thing, same with parking and reverse lights (none of them work when it is acting up). So that makes it sound like a wiring/connection issue. HOWEVER there is something funny to add into the mix. The center brake light is wired straight to the brake switch, that wire also goes into the TIPM and the IPC. The TIPM controls the other two brake lights and the flashers and parking and reverse lights. Parking and flashers go through the multi function switch through the IPC then to the TIPM via CAN. Well since the front parking and blinkers work I don't believe its a CAN or IPC or Multifunction Switch issue, also the brakes are hardwired to the TIPM so if it was the IPC the brakes should still work right. So that doesn't rule out the wiring harness 100% yet, except that the same harness goes to the gate and the power lock and gate ajar features work during this AND if the key is off the center brake light will flash when you hit it, but only flash briefly like as soon as it's triggered there is a short (when it is acting up).

So I have been monitoring some wires and it hasn't acted up yet since I tapped in the multimeter... UG. I'm going to take and wire up some AtoDs to my laptop from the TPIM brake input and outputs and monitor this weekend, but damn this is nuts. I'm leaning towards the TPIM failing but for $200 I'm not ready to just replace it yet.

I've tried disconnecting the battery for a while. Crazy shit. I'm not 100% convinced it's not wiring but it seems odd the center brake light that is wired directly to the brake switch only flashes when it happens.

I think I'll disconnect it's input to the TIPM as well and see what happens. I know that means my other two brake lights won't work but this acts up on the turn signals as well.

Damnit I wish I had a break out harness for this module. I might have to make one.

Just venting but if anyone else has had similar issues I'm open to hearing what you found. I saw a post on another forum very similar but the guy hasn't responded to my request for how he fixed it....
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post #2 of 3 Old 09-10-2010, 12:26 PM Thread Starter
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Location: Indianapolis, IN
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To add to the above, I suppose it is possible that the brake switch wire is shorted out somewhere and that when the module detects a short it kills whatever drives the rear lights. Which would make some sense. This will be my first step. I just wish I knew more about the logic inside the module
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post #3 of 3 Old 09-10-2010, 01:12 PM
Join Date: Jul 2010
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I had similar ever escalating gremlins (first flashing lights, then occasional weak horn noises, later wipers then washers coming on sporadically). Read somewhere about a guy who's TIPM was "bad" and suggested that to my stumped dealer who'd already updated it several times. They called corporate who agreed that was worth a try and replaced the TIPM under warranty. Never happened again.
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