Electrical Problem

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I posted this in the fullsize suv section but it doesn't seem that I can move the post here.

 

Got an '03 yukon that all of a sudden started doing odd things today. When I go over bumps the service brake system message comes up and the red alert light and abs light comes on. At this same time that check engine light comes on briefly and the doors lock or unlock at the same time. After I'm back on smooth road the red alert and abs lights stay on but the rest of the odd behavior stops. Also, once when there was a bump at a stop sign the truck also stalled. Seems like some of the vehicle losses power when going over bumps. I figured it must be a ground bad or possibly the ignition switch. I've cleaned 4 grounds (one high on driver firewall, 2 under driver seat near when frame mounts to body and one behind the front bumper on the driver side) and that hasn't helped. I'm going to go over the wiring under the dash next but was wondering if anyone had any ideas.

 

Thanks,

Colin

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I managed to figure this out today and just wanted to post the solution for anyone else that might run into this thread.

 

Today I had trouble starting the truck but not as bad as the previous day. I had the another look at the wiring under the dash and couldn't really find anything. I decided to go for another test drive and this time the truck stalled and wouldn't restart. Luckily I was only a block away from home so I left it for a bit and came back to it later, again I had issues getting it to start eventually. After wiggling a harness on the passenger valve cover the truck started and I drove it home. So, started to look at this harness a little closer, it's a harness clipped onto a bracket above the valve cover on the pass side that eventually hooks up to the coil packs on that side of the engine. It seemed that moving these wires would allow me to start the truck I eventually traced the wires to the back of the engine block where they met other wire conduits, one of them the conduits had a single black/white wire in it that was severed hanging down onto the block. Once I grounded that wire the truck started and ran no problem. Because I couldn't easily get to the back of the block to reground in the same location it was in I just soldered on a longer wire and grounded the wire to the engine block ground high on the driver side firewall.