ls1nova71

iTrader: (4)

I'm trying to find a way around the GBCM on my 2007 5.3 swap in my 1971 Chevy truck. From what I've read, if you just take it off or it goes bad the alternator will charge at a default setting of 13.8v, which might be fine for something that isn't driven much, but this is going to be my DD in the summer (I think, ), and I don't want to run into problems later down the road, like when the A/C, electric fan, stereo, headlights are all on at the same time.

The easiest way to do this from what I've read, is to change the OS to a year that didn't have the GBCM, which I believe is pre 2005. If I go this route, I'm thinking I'll have to change to a TAC and pedal from a 2003-4, which isn't a problem because I have several of them lying around collecting dust anyway. But what I'm trying to find out is if my 2007 alternator is compatable with the PCM alternator control in the 2004 OS. I would like to keep the alternator just because it's original to the engine and only has 26k on it.

Anybody done this?

garys 68

iTrader: (1)

I kept the module with my 05 5.3. All the wiring is intact except the 1 wire to the BCM.
It will simply charge at 13.8V if removed or dies. (From GM TSB).
I've also been told that you can eliminate the module and wire it directly to the PCM as an 04 (C2 pin 15), no reprogramming needed. Im not sure if it goes to default with this or functions as asn 04 though.
Wiring diagrams for 04 vs 05.
https://ls1tech.com/forums/conversio...le-delete.html

ls1nova71

iTrader: (4)

Yeah, I read that thread, that's where I found out they default to 13.8v.
What I want to know is if you wire it the way you said, if it's actually working or just in default. Have you checked yours to see if you get any other reading other than 13.8v?

garys 68

iTrader: (1)

I wont get a chance to check until next week (out of town til next friday), but I'll disconnect the module and use a jumper wire to see if the 04 wiring makes a difference.

Hart_Rod

iTrader: (3)

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

manuel gomez

i was trying to see if i could revive this once again ..i just did a v8 swap in my 04 but im having the problem with the gcmb and charching at 13.8 ..could you give me more info on this ..the 2 wires to the alt ...2 wires to the bat ...2 wires to the ground and the serial data wire ..please and thank you !

G Atsma

Hart Rod hasn't been here since Feb of this year.

ls1nova71

iTrader: (4)

I'm not sure what wires he used, I just deleted it on mine. HartRod is more active on the 67-72chevytrucks forum, so you may try to reach him there.

manuel gomez

how did you delete yours ? I planning on just wring the alt straight to the pcm

ls1nova71

iTrader: (4)

I wired it like an older one, 2004 I think, then had the tune in the PCM changed to match. Had to swap to ra 2004 TAC module though, but I already had one so it wasnt a big deal.