Weird issues

[Ffmedic147]

I have a 2007 Tahoe and am having multiple issues. First pressure gauge drips and alarms with no change in motor sounds and runs fine. Cut car off and back on its fine. Now oil pressure alarm and pressure gauge shows 40. Second car is going from 2 wheel drive to 4 wheel drive on its own. Selector switch is in 2wd. Third stabilitrack is cutting on and off. I also have a check engine light. Had a reader hooked to it and the reader acted like it was hooked to nothing. What do u all think??? My thoughts is computer is bad

 

[Jeff M]

The computer measures everything based on a reference voltage, I would be checking to make sure the system is not loosing a solid ground connection...if the ground connection is poor it will cause all sorts of strange things to happen. Also if the vehicles wiring harness has been compromised somewhere allowing the wires to begin corroding this also can cause these types of problems. I have seen many time where the harness has been tapped into for the installation of aftermarket equipment such as remote starter or alarm and not properly sealed up...this can cause major problems.

You are correct that it could be the computer or control module but before buying one I would look close at the wiring. I hope this helps, good luck!

 

[Ffmedic147]

Would the ground problem also cause the headlights to pulsate??? Makes since if it would.

 

[Jeff M]

Okay I have seen a headlight pulsating problem twice in the past and both were a challenge to repair. The first one was caused by the alternator, the diodes were failing causing it to throw ac voltage in the line. The second time it was coil pack shorting to ground, this was sending a high frequency spike into the system. Neither of these issues were on a Tahoe but it is something to look at as both things could happen on one.

It could also still be the ground and I would check it closely, make sure you have a good ground connection between the alternator and chassis too. Electrical problems can be very difficult to track down...good luck!

 

[BluRock]

Has similar problems, noticed volt meter at the 11:00 position every time, which indicated to me there wasn't enough battery voltage to operate all the electrical features. Dealer replaced positive battery cable from the battery to the UBEC box as well as the 175 amp fuse. Seemed to have fixed the problem but there remains a problem with the volt meter going to the left (11:00) and the radio turning off. Today, things went really crazy. Clicking noise coming from each front door and nothing worked, wouldn't even crank. Headlights nor anything else would work. Battery voltage was 12.57 using a volt meter. Dealer coming to get the vehicle this afternoon. Dealer has been very cooperative so far and my thoughts are that anything can be fixed.

 

[BluRock]

Interesting, Tow Truck driver tried starting the Tahoe and observed nothing working at all. After loading the vehicle he again tried to start the engine and it did crank up. I'm glad someone from the dealership observed this. After talking with the mechanic at the dealership, he said there were other technical bulletins referencing this issue. Because it started up fine after being loaded, I'm thinking the movement of the vehicle resulted in a bad ground connection making contact.

 

[Jeff M]

BluRock,

It sure sounds like that could be the case, please keep us posted on what they find.