Reprogramming key fobs and remote start?

MICHAEL POWELL

MEMBER
2004 CHEVROLET TRAILBLAZER
4.2L
6 CYL
4WD
AUTOMATIC
180,000 MILES

The fobs and remote starter suddenly stopped working. I tried reprogramming. It goes into programming mode but when I get to holding the open and close buttons simultaneously on the key fob it doesn't program. I also tried programming them with my Launch Diagnostics tool. And it says they're reprogrammed before I can even push any buttons on the key fob. I replaced the batteries. Checked the fuses. Everything works from the driver's door controls. Rear wiper, hatch lock, and defroster work. The wiper is quite slow though and sometimes it doesn't make it back to the seated position. I scanned BCM and no codes came up. I actuated the driver's seat and that worked. I couldn't find a valet button. I just removed the rear panel and didn't see any cracked wires. Since everything works from the door, does that mean the Hatch/lift gate module is working correctly before I try checking for power on all the wires? Are there any simpler things I should try first?

5 Replies

KEN L

MASTER CERTIFIED MECHANIC
42,913 POSTS

Yep, this happens when the driver's door module goes out which is common, here is the location and how to change it out in the images below. When you say you scanned the BCM did you use a CAN scanner? You can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

The DDM is integrated into the main window switch. Check out the images (below). Please let us know what happens.

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Sunday, March 17th, 2024 AT 11:06 AM

MICHAEL POWELL

MEMBER
14 POSTS

I'm using a CAN system. I have a Launch analyzer. I've scanned the DDM, LGM, and BCM. There are no codes. I've actuated the door locks, hatch lock, wiper, and defrost with the scanner and everything works on the driver's door when pressed. I've taken the fobs to the parts store, and they were all putting out signals. I have an old code stored U1162 but nothing currently. The hatch light comes on when I open it manually, but it didn't with the scanner actuator.
Everything seemed to work manually and with the scanner and there weren't any codes. So, I don't think replacing the DDM would fix this but I'm not the expert.
I don't know what to do next.
I read about a valet button but couldn't find one under the driver's side panels.
I have one original Advital fob. And two more used ones. The code is exsdei474s on all of them.
I did read something about having a new key cut on Advital because the old key may be worn out.
Hopefully, someone has the answer.
Thanks

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Tuesday, March 19th, 2024 AT 2:59 PM

KEN L

MASTER CERTIFIED MECHANIC
42,913 POSTS

U1162 code indicates a specific fault within the vehicle's communication network. What condition is this car in and has it been water damaged?

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Thursday, March 21st, 2024 AT 12:41 PM

MICHAEL POWELL

MEMBER
14 POSTS

The truck visually looks like it's only 5 years old. I haven't had any water damage that I know of.
The code isn't current. It was in history. And I'm almost positive that it was only there because I unplugged the LGM when I started to look for cracked wires and corrosion on the plugs and fuses.
I rarely have to do anything to this truck other than maintenance.
This summer everything wore out at once. Replaced the Cat, alternator, battery, water temp sensor and thermostat, IAT, and Fuel filler tube I replaced just this summer. And after I replaced the fuel filler, the code I had for a small air leak, changed to a large air leak. I'm still chasing that problem, but I need to put a smoke tester on it. And my ABS pump motor isn't working. And now the key fobs to top it all off.
So, considering that the driver's door controls everything works manually and I was able to actuate everything in the DCM and LGM with the scanner and there aren't any current codes. Should I conclude that the wiring and modules themselves aren't the problem?
Could the remote car start be causing key fob programming problems?
My landlord put in a new garage door opener, and it seemed like my fobs stopped working the same week. Could that have anything to do with this?
Where is the remote car starter module, behind the glove box?
I'm not sure what they look like or if there's anything I could check for on that. Is there possibly a reset button on it?
Awaiting further thoughts and instructions. Thanks

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Friday, March 22nd, 2024 AT 3:37 AM

KEN L

MASTER CERTIFIED MECHANIC
42,913 POSTS

I don't think the garage door opener would do anything, is there an aftermarket remote start kit on this truck i so I would remove it and put the wiring back to stock. I am surprised that a CAN scan is not telling us more. With all systems on I would check all fuses for power. You could have a maxi fuse that has gone out which can power down many systems which makes sense that there are not more codes.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

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