2007 GMC Yukon Electrical Issues

I have a 2007 GMC Yukon and am having some weird issues with the electrical.

When I turn my blinker on the rear air turns on. Same thing happens when I turn on the radio. When I turn them off the air will go off. When its on it makes a loud whining sound and seems to get louder when I press the gas.

I also noticed my headlights will blink while I am going down the road. Not really sure what that is.

I'm not very mechanically inclined so any help would be appreciated.

Thanks

Welcome from SoCal. A couple of Q’s for ya. Is it a Denali (6.2L) or standard (5.3L)? XL or shorty? Milage when you got and now, plus how long have you owned it? Any recent work done on it and/or is this a new issue?

On these trucks electrical is controlled through a 5V CAN/BUS diagnostic line. When the main battery cables go bad from internal corrosion after a decade (like right now) you’ll have wonky behavior occurring from low voltage & bad grounds. You’ll also have false codes appear because the 5V diagnostic line is too weak to work properly.

Bottom line. Start on solid ground. Replace both battery cables if it has not been done. THEN, see what’s really there and left over. A dealership would love to have you visit and spend 2-$3k on diagnostic time and $200 on battery cables that cost $60 from RockAuto.

^^^^^x2^^^^^ I would first assume that your issue is electrical in nature, and as @petethepug suggested start with the battery cables, followed by the engine to firewall ground, and then the body grounds to ensure that they are in good condition, and the contact points are clean and tight.

petethepug said:

Welcome from SoCal. A couple of Q’s for ya. Is it a Denali (6.2L) or standard (5.3L)? XL or shorty? Milage when you got and now, plus how long have you owned it? Any recent work done on it and/or is this a new issue?

On these trucks electrical is controlled through a 5V CAN/BUS diagnostic line. When the main battery cables go bad from internal corrosion after a decade (like right now) you’ll have wonky behavior occurring from low voltage & bad grounds. You’ll also have false codes appear because the 5V diagnostic line is too weak to work properly.

Bottom line. Start on solid ground. Replace both battery cables if it has not been done. THEN, see what’s really there and left over. A dealership would love to have you visit and spend 2-$3k on diagnostic time and $200 on battery cables that cost $60 from RockAut

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This would be the perfect excuse to get away from the wife and finally buy an oscilloscope to nerd out in the garage ogling at low V square waves.

2007 Tahoe 3.5L 4wd with 286K miles with a myriad of issues that I suspect are electrical. About 12 months ago, I started hearing a hiss in the speakers that changed pitch as RMPs ramped up. Finally ordered the rear radio, heat/AC control module and will replace today. About 6 months ago the key fobs stopped working. The fobs had great range and did not show any signs to malfunction prior to complete malfunction. I replaced the batteries which did not help. About 3 months ago the compass, temperature display on the rear view mirror started malfunctioning intermittently. Seems to switch on an off randomly. Took the Tahoe to the mountains last weekend and it threw a code (cylinder 5 misfire). I cleared the code but the same code popped up a minute later. (Yes, I carry a code reader because it throws a P0403 code once per tank). I stopped and added a bottle of injector cleaner which worked wonders (no codes since). I ran the Tahoe through the car was two days later, drove home and parked it for the night. The next morning it would not start, just one click. The temperature was in the teens. That afternoon after work (warmed in the the mid-30s) it started right up. The Tahoe seems to burn out headlamps every couple of months. I replaced both headlight assemblys but it still burns through bulbs. I'm wondering if a root cause is one or both battery cables. Any guidance on how to test/diagnose would be greatly appreciated.
Matt

Arcing within battery cables or chassis wiring can cause issues like burning out bulbs.

The battery cables, if original, owe you nothing. Replace them and charge the battery to 100%. Test the output voltage of the alternator at the battery while the engine is running to make sure it is not over charging.