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4 Wheel Drive/SUVs/electrical issue 2002 chevy trailblazer


I have checked all fuses and relays and grounds i can get to i replaced the neg cable as it was bad now the problem no door locks no interior lights no electric windows not starting guages not working lights on dash work as well as turn signals but lights on dash dim when ignition switch is turned to start position battery replaced could it be a possible bcm problem and where is it located


The only way to check this out, is to get a voltage meter, and start tracing out the wiring.  Start at the battery, and work towards the fuses.  Check the voltages by trying to start the vehicle and see how much of a voltage drop you get.  I would suggest that you purchase a repair manual from your local parts store, as they have wiring diagrams in them.

There is no real easy way to check this out without tracing out the wiring.

I have seen this problem many times, and the solution has been everything from a faulty battery to a loose wire connection not letting the full voltage through.  Any type of short, or bad connection can cause this.  I had a similar problem in my Grand Cherokee, and it was a broken ground wire in the wiring from the body to the door.


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Carl Brandt


Will discuss suspensions, lifts, lockers along with tire suggestions. Trail ratings and possible requirements needed for specific type of trails. Safety equipment and what you should carry with you. Certified off-road instructor. I am not a mechanic, and 4-Wheeling is a hobby, so if I can't answer a technical question it is due to my mechanical knowledge being related to vehicles that I have owned, or have worked on. I do not have manuals on all vehicles, and I suggest that you obtain a repair manual for mechanical problems and do some research before asking your question. Most mechanical questions can't be answered completely without looking at, or listening to the vehicle in person.


40 plus years of 4 wheeling in a variety of vehicles. At the present time, my major off-road rig is a 94 Jeep Wrangler with a spring over and a 1 1/2" suspension lift. This gives me a total lift of 7" or so. I have lockers front and rear. I have removed the track bars, and sway bar for maximum articulation. I am running a stock 2.5 ltr 4 cylinder with a Jacobs ignition along with a cold air high flow filter. It has 4.56:1 gears with a Dodge NV4500 transmission along with a 3.8:1 Atlas II transfer case. This gives me a final ratio of 105:1 in low gear/low range. Other vehicles I own, are a 96 Ford F-250 with a 6" lift, posi rear end, 36" Hummer tires, 5 speed with a fuel injected 460 ci engine, an 87 Samurai with an 8" lift, Ford 9" rear end with a spool, Chevy Dana 44 front end with an electric locker, 5.88 gears, 16% reduction in high range and a 6.5:1 low range with 35" Baja Claws, and a stock 2003 Grand Cherokee Overland. Trails I have run are the Rubicon (10 times), Dusey Ershim, Fordyce Creek trail, McGrew trail, several trails in Moab, Utah along with local monthly runs.

Lost Coast 4x4's Cal 4-Wheel Corva UFWDA Blue Ribbon Coalition

Certified off-road instructor - Certificates in engineering/electronics

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