BCM issues e38 + t43

[Snap]

ECU / E38 L77 6.0L
TCM / t43 6l80

Please excuse the lengthy post.

I am looking for some help with my swap project and more specifically the body control module (BCM). The ECU/TCM/BCM/Motor/Trans/shifter/brake position sensor/battery current sensor/cruise stalk for my swap are all from the same donor vehicle: 2011 Holden VE Commodore SS. Effectively this is a Pontiac G8.

I want to use the BCM for reverse lights (serial message from TCM), tap up tap down (discrete resistance values from shifter to BCM, BCM then sends serial messages to ECU/TCM), cruise control (discrete resistance values from cruise control stalk to BCM, BCM then sends serial messages to ECU) and smart charging (BCM monitors battery current sensor, and commands alternator field control to ECU via serial messages)

I have done a lot of research and have the ECU/TCM are operational. I have wired the BCM based on the service manuals but I am not convinced the BCM is working correctly (or if I have wired it correctly). The BCM appears to be asleep and does not trigger the reverse lights, no manual shift mode, no tutd commands, or the cruise control on command. I have monitored the following inputs PIDS in VCM scanner they are never activate.
? ECM > Transmission > Gear Selection and Detection > Reverse Switch (always off)
? TCM->Transmission->Shift Properties->Trans Shift Mode(always normal)
? ECM > Systems > Cruise Control > Cruise On/Off (always off)

Here is a copy of the body control operation service manual pages for reference. Body Control System Description and Operation.pdf

This is the BCM power schematics BCM Module Power.pdf and BCM pinouts BCM pinouts.pdf.

All information I have found so far never details the minimum wiring for the BCM but some people appear to have it working as discussed: https://forum.hptuners.com/showthrea...8-ECM-plus-BCM

The following is what I have wired:
Plug Pin Wire Circuit Function Reference
BCM X1 / Green / A 3 GY 1884 Cruise Control Switch Signal
BCM X1 / Green / A 20 PU/RD 5526 AT Shift lever (pin 4) Transmission Electronic Range Select Signal
BCM X1 / Green / A 21 N 4 Ignition switch terminal 3 (Ignition 1 Voltage)
BCM X2 / Natural / B 2 OL 1240 Battery Positive Voltage (INT LAMPS)
BCM X3 / Blue / C 1 B 850 Ground
BCM X3 / Blue / C 2 OY 1640 Battery Positive Voltage
BCM X3 / Blue / C 3 OR 2740 Battery Positive Voltage
BCM X3 / Blue / C 5 B 850 Ground
BCM X3 / Blue / C 8 NB 9004 High speed data GMLAN (+)
BCM X3 / Blue / C 9 N 9005 High speed data GMLAN (-)
BCM X3 / Blue / C 16 NB 9006 High speed data GMLAN (+)
BCM X3 / Blue / C 17 N 9007 High speed data GMLAN (-)
BCM X4 / Black / D 19 L 5985 Accessory Wakeup Serial Data
BCM X4 / Black / D 24 G 646 Reverse lamp
BCM X5 / Brown / E 8 K Voltage sensor (5V)
BCM X5 / Brown / E 9 WG Voltage sensor (- ref)
BCM X5 / Brown / E 10 N Voltage sensor (-)

These are not wired but I am not sure if they could be the cause of the problem:
BCM X1 / Green / A 14 PK 3 Run/Crank Voltage (Separate cranking circuit without BCM) I wonder if this is causing the BCM to ?sleep??
BCM X3 / Blue / C 19 PU/WH 5727 Communication Enable Relay Control (not using these modules eg electronic brake control module EBCM, steering angle)
BCM X1 / Green / A 2 W ignition switch terminal 6 / Ignition Key Resistor Low Reference (VATS Disabled therefore bypassed and not needed)
BCM X1 / Green / A 4 WH/BK 1073 ignition switch terminal 4 /Ignition Key Resistor Signal 5v (VATS Disabled therefore bypassed and not needed)

Here is a log of a recent drive.L77 BCM not working.hpl and the current tune2011 VE Commodore Pontiac G8.hpt

Does anyone have an example of their BCM wiring and what the minimum connections are? Does the Run/Crank wire need to be connected? I suspect this may be affecting the Power Mode(s) and causing the BCM to sleep but not sure. Any help/tips appreciated.

[blindsquirrel]

FYI, there is an aftermarket CANbus box that does all those features you're looking to get from the BCM. Much simpler in a swap than dealing with duplicating all the potentially irrelevant inputs the BCM will look for before it will think nothing's wrong.

https://www.swaptimeusa.com/store/p1...ar_Module.html

[Snap]

Always the way: as soon as I ask you helpful people, the very next thing I check works...

My suspicion of the missing BCM X1-14 PK 3 Run/Crank Voltage wire was on the right track. The BCM did not was not "awake" because it didn't know it wasn't able to enter run power mode. Because I bypassed the BCM for engine cranking, I didn't think it was required - I was wrong. Once I hooked this wire the cruise on/off, manual mode, tutd started working.

More info on power modes and sleep/awake states for anyone interested: Power Mode Description and Operation.pdf

[bonesv8]

Snap:
Good info....did you need the bcm to allow the trans to operate correctly?

[Snap]

Snap:
Good info....did you need the bcm to allow the trans to operate correctly?

No not technically. The trans can work without the BCM but you won?t be able to get reverse lights or tap up/down easily without it.

[ecir55]

bringing up old thread to give props to snap.

There isn't a whole lot of info on the net about using a BCM as standalone. Found a few references with this one that allowed me to get my BCM to work as standalone with a E38 and T43 with about 10 more wires, thanks.

I know this is a tuning forum but it would be nice if there was a section where DIY harnesses were discussed.

Put this cheat sheet together for a motor and tranny for a 07 Escalade. Bold letters on right side of column are schematics that need to be referenced.

[Cringer]

bringing up old thread to give props to snap.

There isn't a whole lot of info on the net about using a BCM as standalone. Found a few references with this one that allowed me to get my BCM to work as standalone with a E38 and T43 with about 10 more wires, thanks.

I know this is a tuning forum but it would be nice if there was a section where DIY harnesses were discussed.

Put this cheat sheet together for a motor and tranny for a 07 Escalade. Bold letters on right side of column are schematics that need to be referenced.

Sweet find! Where did you get this pin out?

[ecir55]

its the pinout for a 07 escalade narrowed down. From what have found most pinouts of bcm's for this generation are not exactly the same so took mine and figured out what was needed and what wasn't based on what others have done.

Purchased a 07 escalde to use the motor tranny that was in running condition and am using it to make it standalone before pulling apart. Was able to do test drives to check functions for what was needed to keep and the functions that weren't needed that would work in a swap. Ended up eliminating over 100 wires from the BCM.

Not as easy as wiring up as the cheat sheet have to reference the schematics to simplify them too, wires go everywhere from the bcm, lol.

[Cringer]

its the pinout for a 07 escalade narrowed down. From what have found most pinouts of bcm's for this generation are not exactly the same so took mine and figured out what was needed and what wasn't based on what others have done.

Purchased a 07 escalde to use the motor tranny that was in running condition and am using it to make it standalone before pulling apart. Was able to do test drives to check functions for what was needed to keep and the functions that weren't needed that would work in a swap. Ended up eliminating over 100 wires from the BCM.

Not as easy as wiring up as the cheat sheet have to reference the schematics to simplify them too, wires go everywhere from the bcm, lol.

Well the thing that interests me is the fact that the TUTD signal is intercepted by the BCM (C1, Pin 20 in your diagram). Perhaps one day when I get some spare time I would like to see if I can bypass that. How can I find the pin out diagram for my car (2014 Chevy SS sedan, aka Holden Commodore VF)?

[hjtrbo]

Go to the Just Commodores forum in Oz. In the VF section, search for the workshop manual, a few links should pop up. She's a big pdf, 11000 pages, 1GB.

[blindsquirrel]

Some models already come with TUTD wired direct to the TCM. Dunno if your trans OS will (or can be forced to) read this pin or not, but here's the diagram for '09 Corvette, for just one example...

screenshot.09-09-2023 04.25.16.png