Intermittent Electrical Problem – Damn!
 

My 02 Suburban just started dropping codes U1000, U1064, B2973, B1477. Along with this the vehicle would not start AND all power was shut down to the accessory bus. The worst part is that this is an intermittent issue – truck will run fine for a few days, then just when I start to think the problem healed itself, the problem presents again, usually at a very bad time. I really didn’t think this was simply a battery problem, but I did install a new battery – of course that didn’t fix anything. I’m not even sure where to start short of replacing the ECM and every wire and other component that has a wire connected to it. Has anyone had the same set of problems or seen these codes? Help!

Re: Intermittent Electrical Problem – Damn!
 

Sounds like something going on with the body control module. I can't help beyond what little bit I found. Sounds like there is a short somewhere or blow fuse/bad relay.

U1000 is a vehicle specific code primarily found on Chevrolet, GMC and Nissan vehicles. It refers to a "Class 2 communications failure." Generally, this code will precede an additional code that identifies the module or area of the failure. The second code may be generic or vehicle specific.
U1064 - Lost Communications With Body Control Module


B2973 OBD Code Definition:
Daytime Running Lamp Output Shorted to Ground

B1477 Possible Causes
Faulty Wiper Hi/Low Circuit Motor
Wiper Hi/Low Circuit Motor harness is open or shorted
Wiper Hi/Low Circuit Motor circuit poor electrical connection
Faulty Body Control Module (BCM)

Re: Intermittent Electrical Problem – Damn!
 

Thanks for the helpful feedback Bill - you found some information on the codes that I didn't come across... Thanks!

Re: Intermittent Electrical Problem – Damn!
 

Before you do swaptronics with the BCM do some troubleshooting.
Check on the serial datalink wires to make sure you don't have loose connections or damaged wires at the BCM.
Check the main BCM Power and Ground connections.

Re: Intermittent Electrical Problem – Damn!
 

x2

Re: Intermittent Electrical Problem – Damn!
 

DTC U1000 and DTC U1255 = Class 2 Communication Malfunction

DTC U1064 = Loss of Communications with DIM (Dash Integration Module) Refer to Data Link Connector (DLC) Schematics Circuit Description.
The class 2 serial data line communicates information between modules. Each module connected to the serial data line is assigned a recognition code, or address. This code is used in order to identify which modules are communicating.
Modules communicate with each other by periodically sending state of health (SOH) messages. When the ignition switch is in RUN, each module communicating on the serial data line sends a SOH message every 2 seconds. This ensures that the system is operating properly. When the dash integration module (DIM) stops communicating on the class 2 serial data line, the SOH that is normally sent on the serial data line every 2 seconds disappears. The module, which expects to receive that message, detects the absence of the message. The module in turn sets DTC U1064 associated with the loss of SOH of the DIM.
Conditions for Setting the DTC
The module does not receive a state of health (SOH) message back from the DIM. The module retries the request 3 times, and then sets DTC U1064.This DTC only sets if U1300or U1301 is not current. Action Taken When the DTC Sets DTC U1064 is stored in the module. The module uses the default values for the initialization data. This DTC does not cause driver warning message to appear.
Conditions for Clearing the DTC
This DTC clears (status changes from current to history) under any of the following conditions:
The module detects a state of health message from the DIM.At each ignition cycle.
A history DTC clears after 50 consecutive ignition cycles if the conditions for setting the DTC are no longer present.
Current and history DTCs may be cleared using a scan tool.
Diagnostic Aids DTC U1064 does not normally represent a failure within the module. When loss of class 2 serial data communication DTCs (DTCs with the letter U as the prefix) are stored as history DTCs, know all possible serial data DTCs set in each module before diagnosing the serial data line. If U1064 is stored in the module memory, inspect for the same DTC stored in other modules capable of storing this DTC. If the DTC is a history DTC, the problem may be intermittent.
Test Description
The numbers below refer to the step numbers on the diagnostic table:
U1064 is the result of loss of communication with the dash integration module (DIM). Note that other modules on the class 2 serial data line may also set U1064 if the DIM is not communicating with the serial data line

DTC B1477 = Retained Accessory Power Circuit Low
DTC B2973 = LF Door Key Switch Circuit Low

Hope this helps.

Re: Intermittent Electrical Problem – Damn!
 

Thanks hatzie - this feedback is golden! I'm going to need to obtain some technical schematics to guide me on this troubleshooting adventure. As you can see from my list of vehicles in my signature, my experience - and knowledge - rests with old school machines that did not have computer controlled everything. That being said, I'm not afraid to get up to speed on the 2002 technology and architecture. Can you help point me in the right direction to find the tech support manual, schematics, etc... that I might need to move forward? Hopefully they might be available online and I don't mind paying for them. Many thanks for the kind of help that is available on this forum!!!

Re: Intermittent Electrical Problem – Damn!
 

You can get the 4 volume printed GM manuals on Ebay. They shouldn't cost more than $300 for a full set. You can find em for between $200 & $300 with patience. The SUV/Avalanche and Silverado/Sierra are different sets. Well worth the money and you can re-sell them when you buy another truck.

Eric O posted this video on where to find aftermarket service info.
http://youtu.be/L1FxoQI_Fw4