mattcotools

Help!! My burb is cutting out like it is loosing connection to the run position on the key switch (but it's not the key switch or the batt.) it only does it when you hit bumps, thought it to be loose batt. connection, then batt. remote start, key switch signal, fuses & relays, no problems found, hooked up the super snap-on scanner- no dtc If you are going too slow up a hill it will die, the power flickerin has caused all sorts of side show type problems -hvac & stuff. Any suggestions????

in2pro

Are all of the ground connections good and solid, don't rely on the cable looking okay. Check both ends if you seen any corrosion the cable is likely bad, check for any swelling along the cables length as the corrosion can and is most likely internal...
Check the alternator and make sure all connecting bolts are secure...

mattcotools

just double checked that by adding an extra cable and it did fail the test.. noticed on this trip however, the average mpg monitor deal resets itself when this happens as well as the hvac failing to function properly after a incident, so any thoughts?

in2pro

check the connections to the BCM, below is the replacement procedure but it should get you where you need to be to check and reseat the connections...
*YOU MUST DISCONNECT THE BATTERY FIRST*


Service Information
2004 Chevrolet Tahoe - 2WD | Avalanche, Escalade, Suburban, Tahoe, Yukon (VIN C/K) Service Manual | Document ID: 855407
--------------------------------------------------------------------------------

Body Control Module Replacement
Removal Procedure
Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

Disconnect the negative battery cable(s).



Remove the knee bolster. Refer to Knee Bolster Replacement in Instrument Panel, Gages, and Console.



Disconnect the brown connector.
Disconnect all other connectors (1).
Remove the BCM from the sliding bracket.
Installation Procedure




Slide the BCM onto the bracket.
Connect all the connectors (1) except the brown connector.
Connect the brown connector.



Install the knee bolster. Refer to Knee Bolster Replacement in Instrument Panel, Gages, and Console.
Connect the negative battery cable(s).
Reprogram the BCM. Refer to Body Control Module (BCM) Programming/RPO Configuration .
Perform the Passlock Learn Procedure. Refer to Programming Theft Deterrent System Components in Theft Deterrent
© 2011 General Motors Corporation. All rights reserved.

mattcotools

checked out bcm connections and pins (ave econ display did not reset). Drove briskly across our newly graded gravel road (very bumpy) It did it again, alot, & ave. econ display reset, abs and check brake system lights went bonkers, and the engine barely stumbled and shuttered me home while the display read "reduced engine power". re-starting it did not help me get home any smoother,

in2pro

Might try running it in the drive way and start wiggling...cables that is..
check the under hood fuse box connectors, check the mega fuse on the firewall.
check wire bundles and boxes under the dash.
I believe the ECM is located near the drivers side fender well near the front of the vehicle, check those connections as well.

mattcotools

been doin that all week, even pulled the eng ecm out to flog it with a hammer while idling in the driveway all the while wiggling and twistin on every wire but the backup light wires. If it werent for my ethics i would have burned this thing to the ground and committed insurance fraud two days ago.

mattcotools

just found loose J plug bolt on ecm green plug,, ran down road and back like a maniac across the bumps and it did not fail. I aint puttin all that plastic back on yet, that's bad luck, but how do you reset all the hvac actuators so I can blow air somewhere besides the windshield?

in2pro

You will need to calibrate the HVAC module, it has a self calibrating mode...
You aren't installing or removing the module just doing the cal...

Important: Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.


Alternate Method (w/o Scan Tool)
Clear all DTCs.
Place the ignition switch to the OFF position.
Install the HVAC actuator.
Connect all previously disconnected components.
Remove the HVAC/ECAS fuse for a minimum of 10 seconds.
Install the HVAC/ECAS fuse.
Start the vehicle.
Wait 40 seconds for the HVAC control module to self-calibrate.
Verify that no DTCs have set as current DTCs.

mattcotools

hey thanks for the hvac info!!!! btw the problem came back this afternoon, made it long enough this time for a brief mental stress vacation, soooo..... the question I have is who stores the average econ info, makes an engine go to reduced power and well pretty much kill everything with strobe light speed, which must be why my hvac goes bonkers.. it is my custom to not 'try' parts for fun, I know why and what then buy parts, guessing has a 95% failure rate in my book, and btw, in2pro, thank you for stickin with me on this one.