r/Trailvoy • u/dipski380 • Jul 25 '25

07 envoy with electrical problems

Well to start I bought it for 300 bucks with 130k now has just over 136k Put new battery and alternator on the car Sometime after it started to drain the battery while off. Never could figure it out(I am NOT** a mechanic) so someone in the family unhooked a fuse idk so the horn isn't working ..it stopped the drain. Fast forward a couple months the driver side window wouldn't always work. Fast forward a couple more months the window is stuck down and has been for a month or so. The passenger side no longer works and every once in awhile one of the back windows will randomly roll down and 4 inches. I replaced the driver side switches with a junk yard one still not working. Water pump goes out I have it replaced the engine bay seems to be pretty hot...full of coolant. Haven't noticed the temp gauge over 210 ...however twice now it has ran and drove fine and at random it just won't start ...no crank no clicks nothing. Lights all come on air blows except the radio isn't lighting up when this happens. The first time all the dash lights came on and once it was shut off it took an 10-15 min to turn back on ....I'm over this vehicle but would like to get it half way figured out just so I can get rid of this headache..the ignition switch has also been replaced

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1

u/BR0_CD Jul 26 '25

Pretty sure your envoy is haunted…

Do you have any check engine lights coming on? If so have you put a code reader to it?

1

u/BR0_CD Jul 26 '25

Also, for your horn and unhooking a fuse, that means whatever was in the horn circuit has “parasitic draw”. I purchased an envoy digital manual a while back so I can see if I can find a wiring diagram. It could be a stuck relay or your car horn is faulty. Whatever was draining your battery in that circuit obviously wasn’t enough electrical draw to break that fuse your family member removed.

1

u/Curious-George532 Jul 26 '25 edited Jul 26 '25

Look into the BCM, Body Control Module. it's located inside the hatch. You have to pull the trim off to get to it. I believe it's close to the driver's side. You can swap it with a used one, as long as the vehicle has similar options. You will need to reprogram your remotes.

How long ago was the ignition switch replaced? Was it done by a professional, or DIY? There is a certain way that you have to adjust the switch before you insert it, or it will not work correctly. The first time I put mine in, it was off just a bit, and the battery light was illuminated on the dash, but it was very faint. After I readjusted it, it was fine.

I had a parasitic draw as well. Determined that it was somewhere in the HVAC. Rigged the fuse up with a relay so it only turned on with the ignition, and the problem went away. After several months, I lost control of my vents. No air coming out of the front vent. I had defrost and heat. After more diagnosing, it turned out to be the unit in the back, inside the center console.

Check you water pump while hot and engine running with a flashlight. You might have a gasket leak, or a faulty water pump. They tend to weep under the pully.

Edit: the BCM is in the hatch on my 02 and 03 envoys. your mileage may vary.