Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

Just for fun - here's the schematic for RPO TP2 aux battery correct for 1972

Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

A 100amp alternator tells me it doesn't have the "luxury" package that is mentioned on the wiring diagrams. From what I can tell it coincides with factory heated seats and all the interior power goodies, sometimes fog lights as well. For sure the 140AMP alt is on 99/00 Denali/Escalades, Z71 Tahoes with heated seats and '00 Limited Tahoes. I've also seen it on Tahoe/Yukon/Suburbans with full power heated seats from 97-00.

Also, if you look into an alternator there is a slick way of mounting one of the NEW (LS motor) alts that are really efficient. Look here.

Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

Nice! Bookmarked the site. I'll look for the alternator when I hit the salvage yards...

Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

I havent forgot about you. I will have those pics on the weekend.

Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

Thanks Greg - no rush. It'll be a winter project for me.

Seems like nearly all the vortec motors have been removed from so-equipped GMs trucks in the salvage yards I've visited in the area. Pete

Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

DeadheadNM, I was at a local yard today and I happened across an Aux Battery solenoid and cables. The only wire I could not GET is the one that is integrated into the harness that is the trigger wire for the solenoid, runs to the interior fuse block. Upon looking at it, I see where it would be easy-peasy to get away with NOT needing a new battery cable from the passenger (primary) battery. I will get pics of it for you soon...

If you want it, it's yours, honestly pulled it knowing you hadn't found one yet.

Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

Absolutely I'll take it! Let me know what I can do to make it easy for you...definitely glad to reimburse you for the effort. Thanks! Pics would be a big plus. Appreciate the help, Pete

Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

There's a dimple in the firewall where a hole can be drilled to pass the harness through to connect to the terminal. Next pic is the solenoid which is mounted next to the washer jar. If you have the battery tray you already have half the installation completed.

Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

I had that system on my truck when I bought it from the previous owner ( had only 11,000 mikes)... I removed it, my truck is the SLE 'Camper Special'..

I may have the pages in my OEM service manual. The harness goes all the way to the left-rear fender well...To plug into the camper... that part is still there.

Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

Helpful pics, thanks!! Looks like the pos goes from the battery to the solenoid. The harness ties in at the solenoid.

Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

Sorry about the wait, had a lot of academic things going on lately, will be glad to be done soon.

Here is what I pulled. Now that I've had a chance to look at it, you do not need the battery cable portion that is different based on vehicle configurations. All they have done is crimped the fusible link lead from the solenoid with the battery cable lead on the same ring terminal that powers the underhood fuse/relay center. The truck I got this from was pretty unique as far as battery cables, so those pictures won't do the "normal" justice. This truck had the auxiliary power center in the dash so there was an additional ground cable, two additional underhood maxi fuse holders and wiring. If you want I can split that ring terminal open and remove that mess of oddball battery cable from what you need.

EDIT: In the first pic, the wire with the blue tag is what connects to the 2nd battery's + terminal. From the factory they shrinktube over the terminal.

Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

Devin you rock! Don't worry about separating anything, I'd be glad to parse through it here. Let me know what you need for the wiring and your time in a PM when possible. Thanks again! Pete

Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

I know its been awhile but here are the pics of dual battery hookups on my 99 Cop Tahoe. Hope this helps and if you need anything further let me know.

Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

I have one more picture

Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

Perfect Greg - a huge help! Looks like y'all have some snow up there. Stay warm. It's a balmy -3C here in Montana :)

Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

Awesome. Glad I found this. I was curious about the spare battery tray and was considering adding a 2nd battery in my '98 before adding anything crazy car audio-wise. I'd been digging through parts diagrams trying to find what this setup looks like. Pics above help. Tossing this exploded pic here in case it helps anyone else. One for the diesel trucks, one for the gas trucks. Look for the fan shroud to tell which is which.

Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

Thanks! I’ve got the harness but just sold my 99 and upgraded to a 2019

Re: How do I correctly wire an auxiliary battery 99 Suburban using existing GM equip?
 

I said screw the factory wiring and just put a rotary switch like boats use in my 98. Didn't want the alternator charging the deep cycle backup battery.