removal of generator battery control module

[rustycars63]

Not sure about tuning what year is your engine and harness ?

[Hart_Rod]

Originally Posted by rustycars63

Not sure about tuning what year is your engine and harness ?

Both 2006

[ls1nova71]

That blue "engine on signal" wire goes to the solenoid thing that is on some brake boosters, it comes from the alternator though, but isnt part of the GBCM. Rob, I would just enable it and see if it changes anything. Does the percentage on the F ever change?

[Hart_Rod]

Originally Posted by ls1nova71

That blue "engine on signal" wire goes to the solenoid thing that is on some brake boosters, it comes from the alternator though, but isnt part of the GBCM. Rob, I would just enable it and see if it changes anything. Does the percentage on the F ever change?

I didn't have a chance to test it. I have a couple of things that I will check when I get time.

[Hart_Rod]

I checked the continuity of all my wiring and everything checks good. I also reflashed the tune with the "Alt L" turned on (1). I didn't get a chance to check it yet, but will this evening. I also found a pretty good article that goes more indepth of the GBCM system: http://www.flatrater.com/samples/Battery/rvc.html

[Hart_Rod]

Changed the tune, and still no difference in output and nothing on the scanner. The only other possibilities are, bad voltage regulator or bad GBCM?

[rustycars63]

Are you getting any codes ?

[Hart_Rod]

Originally Posted by rustycars63

Are you getting any codes ?

No, but I wasn't getting any codes before I wired the GBCM up

[Hart_Rod]

Found a slightly different wiring diagram for the GBCM in this thread:

https://ls1tech.com/forums/conversio...de-anyone.html

[Hart_Rod]

Played with a couple things last night, but nothing worked. Seems like there are 3 options left:

1. Get a new GBCM ($80)
https://www.gmpartsgiant.com/parts/g...-15263889.html

2. Replaced the voltage regulator.....
https://store.alternatorparts.com/d3...ternators.aspx

or

3. Convert to a 4 pin voltage regulator and say goodbye to the GBCM:
https://alternatorstarterrebuildkits.com/product/dr44/

[Hart_Rod]

Found another good article describing the RVC systems:

https://www.motor.com/magazine-summa...september2015/

"There are two types of RVC systems in use—integrated RVC and stand-alone RVC (SARVC). Integrated systems use a battery current sensor to inform a body control module (BCM) how much the battery is being charged or discharged"

[Hart_Rod]

If we are wiring a standalone GBCM, why do any wires need to go to the computer?

"SARVC systems (found mostly on trucks) do not use the BCM for operation. They have a generator battery control module mounted to the negative battery cable, to interpret battery current and voltage and battery temperature inputs. The battery current sensor is internal to the module. This module also directly controls the generator L terminal duty cycle instead of the ECM/PCM."

[Hart_Rod]

Quote:


Originally Posted by clinebarger View Post

So is 100%
"When there is loss of class 2 communication with the powertrain control module (PCM), the module will send 100% duty cycle, 13.8 volts"
"Between 0-5 percent and 100 percent are for diagnostic purposes"
"the generator battery control module is limited between 36-90%"

This is from an older thread:

http://67-72chevytrucks.com/vboard/s...77#post8275277

I'm wondering if the reason I can't get my GBCM to work is because I haven't connected the orange/black wire (serial data K Pin) from the GBCM connector to PCM serial data line? Thoughts?
__________________

[Hart_Rod]

2 wires to the alternator, 2 wires to the battery, 2 wires to ground, 1 wire to serial data port - BOOM!!, it works!!!! Clinebarger strikes again,

[ls1nova71]

Originally Posted by ls1nova71

I probably would if you have it. Seems to me it's a better way of controlling the alternator, and isn't really that much more wiring. It's a couple of power wires and some grounds, then the rest just go between the GBCM and the PCM so there's nothing really to be done. You will have to splice the serial data wire, but that's about it. Here's a schematic in case you need it. The schematic is two pages, even though it looks like one, so that's why it looks funny. I cant put them all on one page and still be able to read them.

Originally Posted by Hart_Rod

I hooked my GBCM up per the instructions/wiring diagrams. Nothing changed, still defaulting to 13.8 V. Does something have to be updated in the tune? Is there a way to troubleshoot the GBCM? TIA

Rob, you're killing me, man!! I assumed you had that hooked up all along..... Well, we all know what they say when you assume something.....

[Hart_Rod]

Originally Posted by ls1nova71

Rob, you're killing me, man!! I assumed you had that hooked up all along..... Well, we all know what they say when you assume something.....

, long story short Eric, my GBCM harness didn't have the serial data wire in it, so I assumed it wasn't needed..... my bad..... It's all good now, .

And just to close the loop, my computer is a 2006 (nothing has to be changed in the tune to make the GBCM work).
The grey and brown wire from the 2006 GBCM harness goes straight to the alternator (nothing goes to pin C 15 or C 75).
Two reds/wht to 10 amp fused source.
Two black/wht to ground.
Orange/black to class 2 serial data line.
Blue wire was deleted.

For a 2005, I believe you may have to connect some wires to the computer (C15 & C75), but I'm not certain.

Eric - where would you recommend connecting into the Class 2 serial data line? Is there possibly an open pin in the PCM blue or green connectors that I could use? Thanks again for all of the help!

[BR3W CITY]

This thread has been a mountain of tech

[cj847]

I am curious about this thread. I am wiring up a 2006 truck LS and had planned to eliminate the GBCM, but now I think I will try to use it.

It seems everyone is worried about getting 13.8V all the time. I am more worried about OVER charging than under charging.

On my 2016 GMC if you watch the volt gage, it drops to 9-10 V after a few minutes on the freeway. There needs to be something to shut down the charging. Otherwise, you will burn up batteries on daily drivers.

What has been the long term effect of eliminating GBCM on daily drivers?

2nd question. What are the minimum wires I can hook up to use the GBCM (my connector was cut off by the people who pulled the engine)?
I think I can wire the power, ground and the two wires from alternator (assuming the charge regulation is in the module). Or is the purple wire to the PCM required?
Thanks.