2008 Tahoe Remote Keyless Entry Issue

[leftwing27]

Hi all,

I have a strange issue with my 2008 Tahoe remote keyless entry system. After the truck sits for a few hours, the key fobs will not unlock the doors right away. I have to try a couple of times and then wait anywhere from 30 seconds to a couple of minutes before the fob will unlock the doors. I have done all the standard troubleshooting... different key fobs, disconnect the battery, check for battery drain, etc. with no luck. Today I decided to hook up a multi-meter to the battery and found that the amp draw from the battery jumps from .05 amps at rest to 1.5 amps when I hit the unlock button. So the truck is responding to the key fob but is failing to unlock the doors initially. I've also noticed that sometimes the climate control buttons will light up while I'm hitting the unlock button on the key fob waiting for it to finally work. I'm thinking it could be a faulty module but I'm not sure which one controls remote keyless entry. Is it the BCM or does it have its own module altogether? Any help is appreciated!

-Paul V.

 

[swathdiver]

Welcome to the forum Paul. The remotes are controlled through the driver's door lock, the Remote Control Door Lock Receiver Module which talks to the BCM.

I would check the batteries and connections in your remotes and determine how old the truck's battery is and what condition it is in. A weak battery can cause all kinds of gremlins, looking good at first and second glance while creating havoc until we figure him out!

Having said that, BCMs and RCDLRs do go bad.

 

[Big Mama]

Your amp draw and ac lights come on bc when you unlock your interior lights come on. I’m with Chris it sounds like a balky remote. It’s hard to believe they both go bad at the same time but think back as we usually change both at the same time. Good luck

 

[leftwing27]

Welcome to the forum Paul. The remotes are controlled through the driver's door lock, the Remote Control Door Lock Receiver Module which talks to the BCM.

I would check the batteries and connections in your remotes and determine how old the truck's battery is and what condition it is in. A weak battery can cause all kinds of gremlins, looking good at first and second glance while creating havoc until we figure him out!

Having said that, BCMs and RCDLRs do go bad.

Thanks for the info. I have new key fobs and replaced the battery in the truck last month. Neither have helped the situation so I think I'll look into the RCLDR next.

 

[leftwing27]

Your amp draw and ac lights come on bc when you unlock your interior lights come on. I’m with Chris it sounds like a balky remote. It’s hard to believe they both go bad at the same time but think back as we usually change both at the same time. Good luck

I wish that were the case but I have one original fob and two new ones with new batteries. The truck acts the same way with all of them. If the fobs were the issue I don't think the truck would respond at all when I first hit the unlock button. And the climate control buttons are the only things that light up. No interior lights, dash lights, headlights, etc. Only the climate control buttons.

 

[swathdiver]

Thanks for the info. I have new key fobs and replaced the battery in the truck last month. Neither have helped the situation so I think I'll look into the RCLDR next.

You'll need access to a bi-directional scan tool like the Tech2, which can interact with the RCDLR and if it needs replacing, flash the new module into the system. Or let the dealer handle it.

 

[leftwing27]

You'll need access to a bi-directional scan tool like the Tech2, which can interact with the RCDLR and if it needs replacing, flash the new module into the system. Or let the dealer handle it.

Thanks for helping out. I'll have to look into that type of scanner. Will I be able to flash a new module with any type of bi-directional scanner or should I stick with the Tech2? Also, any idea where the RCDLR module is located on these models?

 

[swathdiver]

Thanks for helping out. I'll have to look into that type of scanner. Will I be able to flash a new module with any type of bi-directional scanner or should I stick with the Tech2? Also, any idea where the RCDLR module is located on these models?

I do not know if all bi-directional scan tools can program GM modules using TIS2WEB. The RCDLR is on the left side on the D-Pillar, about level with the bottom of the left side glass, slightly above. If you have any newer GM vehicles, you might look into the MDI2/GDS2 instead of the Tech2. I find the Tech2 to be more maneuverable inside the cab though.

 

[Floep]

If the driver door unlock motor is seizing up it will act like that

 

[leftwing27]

Ok, so I picked up a VXDIAG VCX NANO GDS2 scanner which came with Tech2Win pc edition. The only codes coming up are Park Assist Module - U0184 Lost Communication with Radio, Instrument Panel Cluster - U0140 Lost Communication with Body Control Module, and Body Control Module - U0184 Lost Communication with Radio. I have an aftermarket radio so those codes make sense, but I'm not sure what to make of the Instrument Panel Cluster losing comms with the Body Control Module. I tried putting the stock radio back in but it does not fix the key fob issue. The stock radio wiring was not changed either. I used adapters to connect the aftermarket radio.

I also found that, during this 30 second or so time frame when the key fobs aren't working, if I use the key to manually unlock the driver door and open it nothing turns on. I get no interior lights and even the door switch to unlock the doors does nothing. About 10 seconds or so later, presumably when the key fobs would start working, the anti-theft alert starts to go off. I can then hit the unlock button on the key fob to stop it and all is well.

 

[Big Mama]

I’m somewhat surprised no other body control errors if it’s not communicating. I’d guess the original module is the factory one. Can you test it with your new scanner?

 

[leftwing27]

I’m somewhat surprised no other body control errors if it’s not communicating. I’d guess the original module is the factory one. Can you test it with your new scanner?

Yes, but once I'm in the truck with the key on, everything works as it should so testing doesn't yield any new info. It's almost as if the truck is acting like an interior light was left on too long and it kills power to the modules in order to save battery life, but nothing is drawing from the battery while at rest. I'm pretty sure these trucks have that feature, just not sure which module controls it. Would it be the body control module?

 

[leftwing27]

Updating this thread with the solution in case anyone comes across the same type of issue. It wound up being the Body Control Module. I picked one up from Amazon, purchased the subscription to ACDelco to download the firmware, and used the VXDIAG VCX NANO GDS2 scanner with the Tech2Win software it came with to program the new module. Everything returned to normal after that. Thanks again to everyone who responded.

 

[Dirtrunner702]

Hey @leftwing27

If youre still around and can recall your issue before replacing the BCM, was the RCDLR pulling a lot of milliamps or just acting strange?
when I pull the RCDLR out of the circuit I see milliamps drop to 40-50mA but when plugged in it pulls 70-112mA sporadically over and over during a parasitic draw test.

In my case its draining the battery. Negative battery cable assembly has been replaced, SDM-c under driver seat replaced and I have ruled out all other modules.
I have a 2008 Chevy Tahoe Hybrid. No other issues other than 12v battery draining. I will be replacing the positive battery cable this weekend too as the positive terminal gets very hot after running the truck for about 20 minutes.

Long shot on here but worth a shot!