Bought, wrecked, rebuilding a 2009 LMM
- Thread starter malibu795
- Start date
I didn't find that specific diagram, but deducted crank signal from key runs through the BCM, along with DIC, PRDML information, warning light signals. Through several others
Found the BCM pin out. So I'm going to verify it's getting full battery voltage where it should be.
Doesn't explain the "relay clicking" noise under the dash.
Haven't found which wire/circuit actually turns everything "on" through/via the key yet either
Yes engine starts if I jump the relay or starter itself.. though initially GP don't cycle, alternator doesn't come on, water, oil, fuel, coolant, tach, speedo, trans temp gauges are all dead., traction, brake, abs lights are on, T/H light doesn't activate, neither does the line under the PRDML light up, more often than not I can't connect to anything via a scan tool through the OBDII port
From what I've gathered it's switch/BCM/ECM/starter relay with all safety switches in their correct position
What rim posted
Sounds like an issue with the databus. One time while driving an LMM I had to clear codes and my V2 came unplugged during the process and everything went blank but the truck still ran. Pulled over and shut the truck off to get everything to come back on and truck wouldn’t start. Nothing had power, waited 15/20 min then heard a thud under the hood like the ecm reset and everything went back to normal.
I had something similar when loading a tune. Truck wouldn't start. Dash and other stuff acting weird. Disconnected the batteries for a minute and everything was fine afterwards
I agree, looks like a data line issue. The ignition switch is what notifies everything else when to turn on or off. And when the ECM should send power to crank. If this serial data line is interrupted or blocked from making it to the other modules then nothing will work as you experience
I agree, looks like a data line issue. The ignition switch is what notifies everything else when to turn on or off. And when the ECM should send power to crank. If this serial data line is interrupted or blocked from making it to the other modules then nothing will work as you experience
I've had the batteries disconnected for over 24hrs at a time during the week.. nothing changed. Even touching the cables together
If the BCM doesn't tell the ECM to wake up and crank it won't crank, seams it's waking up, but not getting a request to crank signal, hence why it runs when BCM is bypassed to crank
I haven't hooked EFI live up to it since i had to jump it at work. Didn't want to creater other issues due to failed scan/flash
If the BCM doesn't tell the ECM to wake up and crank it won't crank, seams it's waking up, but not getting a request to crank signal, hence why it runs when BCM is bypassed to crank
I haven't hooked EFI live up to it since i had to jump it at work. Didn't want to creater other issues due to failed scan/flash
At one time a new BCM was only like $100 for these trucks. They were that popular for getting fried and needing to be replaced.
New seams to be around 2-250.. used seams to be ,~65-70
Plus what every it cost to reprogram the new unit
Is that Post Malone's illegitimate brother?
Well.. dealer/official outside shop is ~850-900 with the BCM running ~500.00, GM wants 1.25 HRs just to r&r the actual hardpart
a 15 minutes job.. and 1.0hr for programming which is roughly reasonable on the programing side
Found this guy.. ~200.00 with a reman unit, no core... running 4.6 starts of 158 reviews.
a 15 minutes job.. and 1.0hr for programming which is roughly reasonable on the programing side Found this guy.. ~200.00 with a reman unit, no core... running 4.6 starts of 158 reviews.
From what I've found there vin specific stuff additional to VATs which I disabled with EFI live