ocjason

Interesting article. I clipped the part that talks about the GBCM. Seem like it needs to be on the battery negative cable. It says it "interpret battery current and voltage" so i would think it would have to measure all the current returning to the battery? Im not going to run a negative cable back over to the GBCM so i guess i will just extend all the GBCM wires over to the battery on the passenger side frame rail where my batter is.

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.

GrannySShifting

iTrader: (10)

When you say you got it working are you talking about 13.8v charging or got the battery control module outputing 90 percent duty cycle and 15.5v output when load was high?

aleks2505

The whole purpose of the GBCM and going through this trouble is to get it to do the later, otherwise if one's goal is to just make it charge constantly at 13+ V, then why not just eliminate GBCM. Yes, mine works as it was intended but the wiring has to be done as mentioned in this thread. It is actually much simpler than I thought when I first started to tackle this, as I really liked having that feature. Hope this clears it up.

Josh Beverly

I did not pull this GBCM unit from the vehicle I got my engine and computer from. My PCM and alternator are from a 2005 Suburban L59 with the 2-wire alternator. Will my setup charge at 13.8V constantly with only the brown and gray wires going to the PCM on pins 15 and 74?

aleks2505

You have two options: Either pull the GBCM out of a 05/06 truck that had GBCM and wire it up according to the info confirmed in this post (I would recommend this), or bypass it like mentioned in lt1swap.com wiring info, but I believe you will have to get a non GBCM alternator in that case, so I am told.

Josh Beverly

Are you saying I need a 4 wire alternator?

aleks2505

I am only telling you what I heard, sorry, its been a while since I completed my swap. I have GBCM and my alternator is a 2 wire alternator. I do recall in my search that it was mentioned a few times that there was a difference in alternators, not so much the plug but internally, GBCM set up had different alternator. I only mentioned this as it was always on my mind and frankly convinced me to go the GBCM route and hook it up like it was in the donor truck. You have nothing to lose, if you eliminate GBCM, try it and see if you have a charge when you test light the charging system at alternator. I will have to look at the LT1SWAP.com to see which wires need to be moved if you eliminate the GBCM but it is all there. I should have time later today or tomorrow. This thread was more for people who wanted to keep the GBCM. Are you leaning to keeping it or you want to eliminate it?

Josh Beverly

It's not there. The truck is an 86. I would have to hunt one down. I would rather put the pins in 15 and 74 and move on if that will work.

aleks2505

ok, some good info here: https://ls1tech.com/forums/conversio...cm-delete.html
From some quick reading on other forums, you may have to tune out the GBCM if you wont go that route, since you PCM was programmed for it. Again, I think you are better off searching threads were people eliminated GBCM. This thread was for guys like me who wanted to keep it. Those modules are cheap, the system really works and it is extremely easy to hook up. Your PCM and wiring is all set for it too if you got the wiring harness from the donor truck.

LSx '73 Nova

I have just completed connecting this up on my truck 05 Silverado 5.3 swap turbo on ethanol. Battery is relocated to the rear of the bed. I have relocated the GBCM to the Neg cable and made a long harness to run up to the factory PCM>. I have checked and tripled checked the wires are pin out to the correct location and nothing works I only have 10v with everything on lights a/c fans. All parts are new GBCM, Alt, Pigtail etc. I did try and to the delete as mentioned in the previous and that doesn't work either. Not sure what to do next. Should I just go with the Fbody alt and forget this? Any ideas would be helpful.

aleks2505

When you say you have "relocated" the GBCM to the Neg cable, you lost me a bit. GBCM "has to be" on the Neg cable and looks to me it has to be very close to the neg bat terminal. I would not alter that. (did you buy it complete with the neg battery pigtail )? You moving it to the back of the bed may not be a problem, but if you have GBCM far away from the neg. terminal where it hooks up to the battery, that may be an issue. If you have connected everything exactly as mentioned above, then it may be the location of the GBCM module being too far away from neg battery terminal or that you have the incorrect alternator for the GBCM. Buying it all new when it did not come from a specific vehicle as a package is always going to be iffy, even though I am in support of buying things new.

LSx '73 Nova

Thanks, Just to clarify Yes I moved the GBCM to the neg cable at the batteries new location at the rear of the bed. The negative cable is only about 18"inches long and i mounted the GBCM under the bed floor close to the grounding location of the cable to the frame. I then made a new much longer wiring harness so it can be properly installed and integrated in the factory harness etc. I had to buy everything new as when we took out the V6 we sold everything with that motor not knowing we should have kept the components.

favors_poppa

I have a 2006 6.0 from an Escalade in my swap. 2 wire alternator. Donor originally had the 8 wire GBCM on the battery. I’m attempting to get alternator working. My swap harness has the 4 pin connector. I attempted to try the instructions on here but still defaulting to 13.4. Two wires to battery, two to ground, brown and gray to alternator, and Orange/blk to pin 2 on OBD2 connector and I’m still at 13.4. Is the module bad or am I doing something wrong? Module part number 15263889 is showing discontinued but ones I’ve found online are $80.

LetsTurboSomething

https://ls1tech.com/forums/conversio...hrow-away.html

Do what this thread describes instead. It's just much easier. I messed with the GBCM for a year and the things SUCK. They're not doing anything helpful for a swap and the PWM generator conversion is about a 5min install and you get what ever amount of charging you want, fully adjustable with a button on the dash or under the hood.

favors_poppa

Very much appreciated! I read that thread before but couldn’t find it again. I ordered the PWM like Bill listed with adjustable output voltage and should be here Wednesday. Anyone know if Bill still makes the box for them?

mhunt

This seems like one of the few threads on the Internet that seems close to hammering home the re-use of the factory GBCM.

I am in need of this info as my donor truck ('05 Tahoe) has the 2 wire alternator. It appears to me that the GBCM is nothing more than a Current meter that is measuring the current coming back to the battery via the Negative cable, so to answer some of the questions, yes, it has to be on ALL of the negative cables feeding back to the battery, hence why it is near the battery since there is usually only one wire by the time the ground cable is getting back to the battery.

Also, since the current flow direction is important, those that have had troubles getting your GBCM to work properly, are you sure the GBCM is oriented as the factory did so that it captures the current flow in the proper direction ?

I plan to try and re-use mine since, in theory, you get the best of both worlds, needed increased voltage when running accessories and less drag/wear when you don't need the extra juice

Escalado

Hello, I’m attempting to hook up the GBCM from an 06 sierra to a 2000 Silverado, to control a DR44G alternator. I’ve temporarily hooked the charge indicator wire to the positive battery post, with a small light bulb wired in to reduce amp. I’ve swapped/set up the GCBM in place, but my problem is I have no pin 75 on the PCM. Is there any way to have this alternator run properly using just pin 15 of the PCM? Any tips on making this swap work? I have a full donor 06 to take parts from

70f100

can I put Pin K (Orang/black) to pin 59 @ the pcm or can i splice to Pin 58? What do yall suggest I do? thx!!