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Discussion Starter #1
Hey everyone,
my 2008 Silverado 3500 stopped recognizing the key fobs. At first I thought it was the key fobs so I changed the batteries and no improvement. I checked every fuse I could think of and I also checked all the wire harness connections. I searched the thread and saw a few other people had similar issues but I never saw a solution to the problem. It could be unrelated but I noticed a water leak on the top driver's side corner of the windshield. Upon further inspection I saw where the windshield had been replaced and the installer or previous owner had attempted to fix the leak with clear silicone. I found no evidence of water on any of the wires or wiring harnesses. Any help would be appreciated.
-Coop
 

LHN...We ARE the Joneses
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It could be the battery contacts in the remote.

Open it up, pull the battery, and use a pencil eraser to clean the contacts. See if it make a diff.
 

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Discussion Starter #3
All 3 key fobs aren't working. My first thought was that the key fob that I use most often had died but even with a brand new battery I wasn't getting any response from the truck.
 

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Discussion Starter #4
I also disconnected the batteries on the truck thinking that maybe that would reset the computer but no luck there either.
 

Awooga, Awooga
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Did you try the remote relearn procedure?


INSERT key and TURN the ignition to ON (just shy of starting vehicle without cranking engine).
PRESS the Trip Odometer Reset Button until 鈥淩ELEARN REMOTE KEY鈥 is displayed.
PRESS and HOLD the Trip Odometer Reset Button for approximately 3 seconds until 鈥淩EMOTE KEY LEARNING ACTIVE鈥 displays. Vehicle is now in Programming Mode.
PRESS and HOLD LOCK and UNLOCK buttons at the same time on first remote for approximately 15 seconds. An acoustic signal will sound indicating successful programming.


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You might also have your two truck batteries load tested. When they get old and weak all sorts of electrical gremlins start to pop up.

Could be your BCM too but Id try all the above from all posts, including the battery testing, all of which cost nothing. before I even thought about the BCM
 

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Discussion Starter #7
Did you try the remote relearn procedure?


INSERT key and TURN the ignition to ON (just shy of starting vehicle without cranking engine).
PRESS the Trip Odometer Reset Button until 鈥淩ELEARN REMOTE KEY鈥 is displayed.
PRESS and HOLD the Trip Odometer Reset Button for approximately 3 seconds until 鈥淩EMOTE KEY LEARNING ACTIVE鈥 displays. Vehicle is now in Programming Mode.
PRESS and HOLD LOCK and UNLOCK buttons at the same time on first remote for approximately 15 seconds. An acoustic signal will sound indicating successful programming.


Sent from my iPhone using Tapatalk Pro
the "RELEARN REMOTE KEY" message would flash and then disappear. It would never switch to "REMOTE KEY LEARNING ACTIVE"...

You might also have your two truck batteries load tested. When they get old and weak all sorts of electrical gremlins start to pop up.

Could be your BCM too but Id try all the above from all posts, including the battery testing, all of which cost nothing. before I even thought about the BCM
407Driver, Is there a way to test the BCM?

After all day of the keyless entry not working, the truck all of a sudden started working again. I haven't changed anything today. I'm wondering if maybe some moisture got somewhere it shouldn't have and caused these problems? I'll go get the batteries tested this weekend and let you know what the status is.
 

Awooga, Awooga
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the "RELEARN REMOTE KEY" message would flash and then disappear. It would never switch to "REMOTE KEY LEARNING ACTIVE"...







407Driver, Is there a way to test the BCM?



After all day of the keyless entry not working, the truck all of a sudden started working again. I haven't changed anything today. I'm wondering if maybe some moisture got somewhere it shouldn't have and caused these problems? I'll go get the batteries tested this weekend and let you know what the status is.


Interesting. You might be onto something. I鈥檓 beginning to think you may have an intermittent ground.


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Discussion Starter #9
This might be a silly question but I'm going to ask it anyway: What is the best way to go about finding an intermittent ground? I read somewhere else on the forum that the Duramax has 15 grounds dispersed throughout the vehicle. So, just basically go around and find, clean and tighten all the grounds you can find?
 

Awooga, Awooga
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This might be a silly question but I'm going to ask it anyway: What is the best way to go about finding an intermittent ground? I read somewhere else on the forum that the Duramax has 15 grounds dispersed throughout the vehicle. So, just basically go around and find, clean and tighten all the grounds you can find?


I wouldn鈥檛 consider that a silly question. I鈥檓 a USN submarine electronics technician and understand that electricity can be difficult to grasp.

What you鈥檙e describing above would be checks for an inadequate ground, which can affect how electronics function, but I don鈥檛 think that鈥檚 your issue. Realistically, you are probably dealing with something on the other end of your electronics that is normally not grounded (isolated from ground) that is being grounded.

You mentioned water/moisture earlier and that can definitely do it. Other examples include a chaffed wire where then bare wire is contacting something that is grounded. For example, in a perfect world, the current leakage from the positive terminal of your battery to ground should be 0mA. If you had current leakage that was sufficient, you could drain your battery and drop voltage low enough that circuits no longer function properly (this is an example of a ground that is not desirable). However, at the other end of your battery is the negative terminal that is grounded and if you lift that cable, you would have an inadequate ground that would also prevent a circuit from working properly.

Trying to find what鈥檚 grounded is varsity level troubleshooting and can be very difficult. One thing that makes this difficult is that most vehicles have some electronics that are slightly grounded, but continue to operate normally, so no one is aware the problem exist. The other thing that makes finding a ground difficult is that it may appear only when certain things are energized or de-energized (as power is applied to different things, relays actuate and energize other circuits that may be grounded). I have spent weeks trying to find grounded electronics on a submarine.

Honestly I鈥檓 very suspect of your mention of moisture. Your best bet is to see if you can find where the water is leaking to and make sure any electronics in that area is completely dry. Then stop the moisture from getting there in the future.


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407Driver, Is there a way to test the BCM?
The BCM is located around the top of your brake pedal. I think it has a pink connector. I do not know of a way to test it other than to have a dealer hook the truck to a Tech 2. You might look for frayed wires in that harness though, possibly something near the brake pedal that could be jostled or rubbed against?

And always remember, when doing this troubleshooting, Remove BOTH Neg battery cables FIRST!

Then do what you are doing and reconnect the battery cables LAST.

This procedure will keep you from grounding something that does not want to be a cooking some expensive electronics.

I know, it is a PITA, but this forum is replete with lines like "I thought it would be OK" or "I wish I had". Dont be that guy.
 

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Discussion Starter #12
Thanks for the tips Gents. It's currently raining so I should be able to see any leaks. I'll disconnect the batteries and hunt for chafed wires this weekend.
 

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Discussion Starter #13
The BCM is located around the top of your brake pedal. I think it has a pink connector. I do not know of a way to test it other than to have a dealer hook the truck to a Tech 2. You might look for frayed wires in that harness though, possibly something near the brake pedal that could be jostled or rubbed against?

And always remember, when doing this troubleshooting, Remove BOTH Neg battery cables FIRST!

Then do what you are doing and reconnect the battery cables LAST.

This procedure will keep you from grounding something that does not want to be a cooking some expensive electronics.

I know, it is a PITA, but this forum is replete with lines like "I thought it would be OK" or "I wish I had". Dont be that guy.
weekend update:
I disconnected the batteries and had them load tested. They came back as very healthy. I continued looking through the wiring harness to try to find any bare wires. I never found anything obvious. After I removed the BCM I saw this suspicious white line on it that made me think it had been getting wet. I bought a new BCM and I just need to get it programmed before I can use it. After I reassembled everything with the old BCM, the wireless entry was working and a few other issues had resolved themselves...(I discovered some issues with the AC system that seemed to fix themselves over the weekend...) Its frustrating because I haven't found the culprit. While on my hunt for the water entry point, I blew compressed air through the drain lines coming from the sunroof and then flushed them with a 50/50 mixture of water and bleach. I also found these loose wires with the ends covered with electrical tape.. Does anyone know what they are for?
 

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LHN...We ARE the Joneses
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Does anyone know what they are for?
Trailer brake controller hookups....when the unreliable IBC craps out, you have the provisional wiring to install a reliable P2/P3 controller.
 

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weekend update:
I removed the BCM ..................... I reassembled everything with the old BCM,................. the wireless entry was working and a few other issues had resolved themselves...(I discovered some issues with the AC system that seemed to fix themselves over the weekend...
OK, think about what you did and what happened. Basically you disconnected teh BCM and reconnected teh BCM. Things changed, for the better.

I do not believe that the BCM, while sitting on your bench or shelf healed itself. It is much more likely that the connector or the wiring for the connector is the culprit.

It may be right at the connector or anywhere else back along that harness where it could rub and chafe. It sounds to me like it is near that connector though because moving the wiring by disconnecting it altered the issue

If I were you Id remove the BCM and use a thin file or small brass brush to try and clean the pins in the connector.

While it is disconnected Id take a VERY hard look at the connector itself to see if any pin/s are possibly loose in the connector. Look at the wiring on each and every pin to see if it is chaffed.

before putting it back together and after having cleaned the pins use a bit of dielectric grease on the end of the wiring harness connector. Push a small bit into each hole so the pins on the BC will be coated. This is to keep any moisture out of the connector.

Good Luck, keep us advised
 

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Discussion Starter #16
OK, think about what you did and what happened. Basically you disconnected teh BCM and reconnected teh BCM. Things changed, for the better.

I do not believe that the BCM, while sitting on your bench or shelf healed itself. It is much more likely that the connector or the wiring for the connector is the culprit.

It may be right at the connector or anywhere else back along that harness where it could rub and chafe. It sounds to me like it is near that connector though because moving the wiring by disconnecting it altered the issue

If I were you Id remove the BCM and use a thin file or small brass brush to try and clean the pins in the connector.

While it is disconnected Id take a VERY hard look at the connector itself to see if any pin/s are possibly loose in the connector. Look at the wiring on each and every pin to see if it is chaffed.

before putting it back together and after having cleaned the pins use a bit of dielectric grease on the end of the wiring harness connector. Push a small bit into each hole so the pins on the BC will be coated. This is to keep any moisture out of the connector.

Good Luck, keep us advised
So, on the drive to work this morning the AC started changing modes, the driver's side audio went out on the stereo, and the keyless entry wouldn't work. Due to this intermittent operation, I definitely think you are correct that it is a wiring issue somewhere. I think the only way to get a good enough look at the wiring is to disassemble the dash. I'll keep you posted on that process. Also, I'll take a good look at the connectors themselves.

Trailer brake controller hookups....when the unreliable IBC craps out, you have the provisional wiring to install a reliable P2/P3 controller.
Thanks! I was worried that those wires were some aftermarket thing that a previous owner had added. It makes me feel better to know that those wires came from the factory.
 

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Discussion Starter #17
I opened the dash, luckily I only had to remove one panel in order to gain access to the area I needed. I disconnected everything I could see and inspected all the wiring. Unfortunately I discovered no chafed wires, or exceptionally loose connections. I added dielectric grease and reassembled the BCM. I am still getting poor reception on the wireless remotes (which all have new batteries). I haven't had the speaker or ac stop working since I've added the dielectric grease... Now I'm kind of just holding my breath and waiting... My next step would be to take it to the dealership if I continue to get intermittent operation. Once again, thanks for all the advice and tips! I appreciate it!

I attached a picture of one of the connectors that had a slightly loose wire. It seems to be making contact when the connector is plugged in though. Is there any way to fix a single wire inside that type of connector or do you just have to replace the entire harness?
 

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The wire connector can be broken down and a new pin installed on the loose wire, but you need the correct tools... I'd look for a you tube video.

Also, having been a tech for 4 years on video games, the full arcade upright ones... issue still could be on the BCM board. bad traces are hard to see... pulling the board and reinstalling it can flex the trace, or a loose solder joint...

Reinstall the BCM and then slowly start wiggling harnesses and try to get issues to come and go...

Good luck...
 

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Discussion Starter #19
All,
I want to say thank you for all your help and your suggestions. I took the truck to the dealership so they could reprogram the BCM and they started talking about a wireless door lock receiver. I had never heard of such a part. Long story short, they checked that and it was the problem and not the BCM. 500$ later, I got my truck back. I wish I had known about that part before I took the truck in. I found the part online for 66 bucks... Hopefully this information can help someone else! Apparently the part is located on the C pillar (my truck is a crew cab) behind some trim pieces. Again, thank you for all your help and suggestions. It was greatly appreciated.
- Coop
 
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