I did it! I FINALLY did it!! Dual batteries

[DCIV]

Coop

[Chris GTO TT]

[alienviking]

[Jeff V.]

[DCIV]

Exactly!!!!


Coop

[Jeff V.]

Study hard.

[DCIV]

So is it like I read? Charges both but only starts and uses one?


Coop

[Jeff V.]

Kinda looks that way. But only when the aux battery relay is closed. I think it's controlled by the PCM. I'll get the power distribution schematics next.

[aaronatstate]

I’m guessing it only uses one unless lower voltage or high current draw is detected and it starts using both. Also looks like the second battery can be used to start it as well.

[Jeff V.]

This is from the service manual.

The auxiliary battery relay coil is energized with the engine running through the fuse block and wiring, thus closing the relay contacts which allow the battery to be charged from the vehicle's generator via the battery junction block. The auxiliary battery relay is permanently grounded so any time the ignition switch is in the run position the relay will be energized.

The auxiliary battery is only used for accessories and is not part of the vehicle starting system. However if the primary battery fails and in need of an jump start, follow the service information for Jump Starting In Case Of Emergency using appropriate battery jumper cables.

Check your owners manual. I wonder if you can jump it off the secondary battery if the primary is dead.

[DCIV]

No can do….no manual to be found.


Coop

[Jeff V.]

https://www.dezosmanuals.com/wp-content ... Sierra.pdf

There's nothing in there specific to jump starting a dual battery setup.

[alienviking]

Well that gave it away!

[Jeff V.]

Oops

[aaronatstate]

Bet that manual says something about that fuse link in there to connect the second battery to the starter.

[aaronatstate]

It actually doesn’t say what to do in the manual you posted Jeff

[DCIV]

Well that gave it away!

Haha. It’s all good. It’s not at the house to post pics. It’s a long story. I will make its own thread when I get it here. But here is a pic from the Facebook ad. I can’t believe how clean it is under, I would put it up against new cars at the dealer. It’s impressively rust free.


8.1 Allison 4:10 gears……and factory dual battery set up on a gas engine!!! Pretty rare option, not sought after, just not needed as all I found is that the second batter goes to the trailer only. I know jeff will be able to tell me though.



Crew cab king bed. It’s 14” longer than the avalanche. I am worried about the driveway.


Coop

[Chris GTO TT]

Crew cab 8ft bed!? Is one end in NC while the other is in AR?

[DCIV]

It’s only 14” longer than the avalanche.


Coop

[Jeff V.]

2001 Sierra brochure. Some nice diagrams and frame pictures in there.

https://www.auto-brochures.com/makes/GM ... a_2001.pdf

Page 3 pretty much sums up Coop. "You can never have too much truck"

Speaking of...

It’s only 14” longer than the avalanche.

That's the short bed. Crew cab long bed is 256". 34" (nearly 3 feet) longer than the Avalanche. It's on page 47 of that brochure.