2018 Silverado electrical problems

[GrePat]

I purchased a GM Certified 2018 Silverado 1500 Crew Cab Z71 in June 2021. The dealer has a 1 year bumper to bumper warranty on the truck because it was GM Certified plus I purchased the extended 5 year warranty.

 

It is starting to become possessed with weird intermittent issues.

 

First oddity: Normally, when you use the key fob to lock the doors, then push the lock button a second time, the horn beeps once. It sometimes does not beep the horn. I checked the settings and that feature is definitely turned on, yet sometimes on the 2nd press of the lock button I get no horn beep. Later, the horn will beep normally when the lock button on the fob is pushed a second time. No rhyme or reason for when it does or doesn't work like really hot, or really cold or raining, etc. Just stops working randomly. Horn works when horn button on steering wheel is pushed. Sometimes horn will work or sometimes won't when the panic button on the fob is pushed. The temperature outside right now is minus 2 and no horn when buttons on fob are pushed.

 

Second oddity: When the weather turned off cooler and winter set in I started having a problem where the right directional is turned on, after the 3rd blink it will start to hyper blink and a message comes up on the dash that says "Service - Right Rear Turn Indicator Failure". I have gotten out and looked and  BOTH lights in the taillight assy are blinking as well as the front bulbs and markers with no bulbs out or dim. Left directional signal will be working fine. Next time I drive the truck the problem has gone to the left side with the right side working fine. Next time I drive it will happen on BOTH sides. Hop in to drive again and both sides are working fine.

 

This issue "COULD" be caused by very cold temperatures. It is currently below zero here today and both directionals are hyper blinking with the SERVICE message on dash display AND the horn isn't beeping on the second press of the lock button on the fob AND the panic button isn't making the horn beep. Parking lights blink 3 times when panic button is held but no horn.

 

Third oddity: When I remote start the truck, 99% of the time it doesn't turn on the parking lights and the LED strip under the headlights. They DO blink when you push the LOCK button and they do blink once when you hold the START button. They are supposed to come on when the truck starts and stay on until it shuts off. I found the ONLY lights that come on when remote started are the 2 plate lights. Kind of defeats the purpose of knowing if the truck is running, or not. I have to watch for exhaust steam at the tail pipe!

 

I did have trouble with the mirrors on the truck. Issues with those were the rear facing white LED's that come on with the cargo lights. First the passenger side white LED's would blink on and off or go dim to bright, then shut off all together. About a month later the drivers side LED's went to a dim level and stayed there. The heated mirror on the passenger side worked fine but the one on the drivers side didn't work at all. The arms also would not hold the mirror in position because the wind would slowly push them back toward the truck as you drive down the road, more of an issue when you had them extended to tow a trailer.

 

Last week I took it to the dealer that I bought it from. Here is what they have done so far...

 

They had my truck for 3 days. They did not provide a "Courtesy Loaner" as promised when I bought the truck because due to COVID, they don't have any loaner cars and the rental car place they normally get cars from didn't have one, either.

 

They replaced the mirrors but they are NOT the same as the ones that came on the truck. The ones that came on it had these features; large mirrors were heated, power adjusted, white LED's that come on with the cargo lights, red arrow in the glass that blink with the directionals, white LED ground flood lights that come on when you remote unlock doors or open a door, 8 LED's on the front side of the mirrors with 2 of the LED's that came on with the parking lights and the other 6 would blink with the directionals.

 

The mirrors they put on the truck do not have the white LED ground flood lights and the amber lights just come on with the parking lights with no blinking with directionals. They do have heaters in them and the red arrow in the glass. I have told them I want what was on the truck when I bought it. They claim the mirrors that came on it must have been aftermarket and they ordered the ones they did based on the VIN. I call BS on that!! $200 mirrors vs. $550 mirrors. Going to fight them on that one!

 

I have a dash cam with a power control module I installed that requires a constant 12 volt, a switched 12 volt and a ground so the dash cam comes on with the key, goes into parking lot mode when the key is turned off and then will shut the camera off if the truck battery drops below 12.3 volts. The dealer said that I had tapped into a BUS line for the power in the fuse panel on the passenger side. Their tech said this "may" be causing the issues with the lights and other features. After working on it they said they were confident they had resolved the issues with power and to leave the dash cam controller installed as it was but if the issues with lights returned to remove it.

 

The night I picked the truck up I remote started it... no marker lights came on when the truck started and just the plate lights were on. I did have the horn beep when the lock button was pushed 2 times but when I pulled out of their parking lot both right and left turn signals hyper blinked with the SERVICE message on the dash. The next day I removed that controller and now have the dash cam plugged into a 12 volt accy socket that turns off with the key. Still having the same issues with the lighting. Blows that theory!

 

Just to rule things out with possible interference from ANY of the devices, I unplugged every single accessory inside the truck. I have a fire scanner, radar detector, dash cam and wireless cell phone charging pad. With NOTHING plugged in, all electrical issues and malfunctions continued to malfunction.

 

The truck is going back to the dealer this Friday. I want these problems fixed! If it is an issue with the BCM or other onboard computer module then I want it replaced in warranty! I don't want to take the chance that some critical system will suddenly decide to malfunction! ... stuff like headlights or wipers or the engine!

 

The dealer said "They weren't able to replicate the problem". One thing I figure is it has to do with the cold temps. The problem is the dealer pulls the truck inside a warm building and starts working on it. Everything is warm so of course they can't find any issues if it is related to the cold. They need to sit outdoors where it is 10 degrees out and work on it! I'm pretty confident they will see the issues I've described. Dealer said there are computers all over the truck. They were able to see some stored codes in the computer referencing "low voltage shutdown". They said various computers will "Go to sleep" to conserve battery power and sometimes they don't wake up properly." We'll see what they find during round two! They had said if the issues turned out to be due to non-oem wiring that was done in the truck then all troubleshooting and diagnostics for time spent would have to be paid by me!

 

Anybody else have issues like these? Any suggestions would be appreciated!

[steelerdude15]

Here are a couple of things to check first. Since the truck is going back to the dealer on Friday, ask them to test the battery. Sometimes when a battery is on its way out, they will cause electrical issues. Another thing to check and this is a common issue, is to check the ground behind the passenger front wheel. When this ground gets dirty, it can cause the truck to have electrical issues. I would clean it and make sure it’s bolted down tight.

[John3971]

Hey GrePat did you find the issue and solution to your issues?  I am having random horn honking when locking and unlocking no rhyme or reason for it.  Sometimes it honks even if it is optioned to no feedback when locking and honks twice when locking with key-fob followed by 3-5 rapid honks within a minute.  On rare occasion it'll honk once 5-8mins after locking it. I did a battery reset and now the alarm will not go off when a door or the tailgate is opened.  The battery reset did make the option of horn feedback work as it should but no alarm horn now.