What is it for? Firewall relay/solenoid - The 1947 - Present Chevrolet & GMC Truck Message Board Network

esbstuff · 09-11-2016, 11:48 PM

On the passenger side firewall of an 05 2500hd. The truck was already mostly stripped when I got it. It only has one wire left on it that appears to go down to the starter...

Thanks in advance!

**truckdude239** · 09-12-2016, 12:13 PM

its a starter soionoid but shouldnt have been on that truck for the starter

izzy_Britton · 09-12-2016, 05:23 PM

Could be dual battery isolator solenoid thing. I have one similar on my 86. Previous owner installed extra battery in bed of truck for over cab camper.

Similar to started solenoid but different.

esbstuff · 09-13-2016, 09:20 AM

Quote:

Originally Posted by truckdude239

its a starter soionoid but shouldnt have been on that truck for the starter

That was my first thought, but I came up with nothing on a search.

What baffles me is the factory studs. Painted red (just like the truck), looks like all the others but I have 6 other 99-07 trucks including 03, 06 and other 05 and none of them have these 2 studs.

amerskier · 09-14-2016, 07:36 PM

It is the factory relay for a dual battery setup

esbstuff · 09-16-2016, 01:01 AM

Quote:

Originally Posted by amerskier

It is the factory relay for a dual battery setup

I finally figured out that yes it is for a dual battery setup, but more specifically a camper special package dual battery isolator.

izzy_Britton · 09-16-2016, 01:22 AM

i was gonna look under the hood of mine today to see if there was lugs, just for the desire to know.

I was thinking that if your truck is a HD version it might have the dual battery isolater as well since I THINK the HD versions all had diesel options? just a thought.

-Izzy

esbstuff · 09-16-2016, 09:27 AM

Quote:

Originally Posted by izzy_Britton

i was gonna look under the hood of mine today to see if there was lugs, just for the desire to know.

I was thinking that if your truck is a HD version it might have the dual battery isolater as well since I THINK the HD versions all had diesel options? just a thought.

-Izzy

This one is a 6.0... The kicker is someone removed the second battery tray and put the fender brace in, so it 'looked' like it didn't have the dual battery option.

izzy_Britton · 09-16-2016, 09:52 AM

Probably a car lot changed it over to save having to buy another battery. They do that crap around here all the time. I deliver used car and truck parts, car lots and body shops are our biggest customers...

The 04 2500hd I bought a few months ago came with 8.1, it HAD dual batteries when I looked at it and bid on it (impound), web it arrived at my shop everything 'dual' was missing, the tow truck driver apparently thought he needed it more than he thought I did. Bastard.

09-11-2016, 11:48 PM	#1
esbstuff Registered User Join Date: Jun 2011 Location: St Robert, Mo Posts: 730	What is it for? Firewall relay/solenoid On the passenger side firewall of an 05 2500hd. The truck was already mostly stripped when I got it. It only has one wire left on it that appears to go down to the starter... Thanks in advance! Attached Images

09-12-2016, 12:13 PM	#2
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,238	Re: What is it for? Firewall relay/solenoid its a starter soionoid but shouldnt have been on that truck for the starter __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

09-12-2016, 05:23 PM	#3
izzy_Britton Registered User Join Date: Apr 2013 Location: Nor-Cal Posts: 632	Re: What is it for? Firewall relay/solenoid Could be dual battery isolator solenoid thing. I have one similar on my 86. Previous owner installed extra battery in bed of truck for over cab camper. Similar to started solenoid but different. __________________ WHO_DCTC - Wifes 05 Z-71 Build - Now defunct as she decided she wants an Escalade too Cream Puff - LS'd Square - Slow going on the back burner Tripple Threat - 3 Wrecks for the price of one build thread Project Delongdium - Step-Sons Plastic Clad 2003 Avalanche - DONE and Delivered.

09-14-2016, 07:36 PM	#5
amerskier Registered User Join Date: Apr 2016 Location: Wenatchee Wa Posts: 10	Re: What is it for? Firewall relay/solenoid It is the factory relay for a dual battery setup

09-16-2016, 01:22 AM	#7
izzy_Britton Registered User Join Date: Apr 2013 Location: Nor-Cal Posts: 632	Re: What is it for? Firewall relay/solenoid i was gonna look under the hood of mine today to see if there was lugs, just for the desire to know. I was thinking that if your truck is a HD version it might have the dual battery isolater as well since I THINK the HD versions all had diesel options? just a thought. -Izzy __________________ WHO_DCTC - Wifes 05 Z-71 Build - Now defunct as she decided she wants an Escalade too Cream Puff - LS'd Square - Slow going on the back burner Tripple Threat - 3 Wrecks for the price of one build thread Project Delongdium - Step-Sons Plastic Clad 2003 Avalanche - DONE and Delivered.

09-16-2016, 09:52 AM	#9
izzy_Britton Registered User Join Date: Apr 2013 Location: Nor-Cal Posts: 632	Re: What is it for? Firewall relay/solenoid Probably a car lot changed it over to save having to buy another battery. They do that crap around here all the time. I deliver used car and truck parts, car lots and body shops are our biggest customers... The 04 2500hd I bought a few months ago came with 8.1, it HAD dual batteries when I looked at it and bid on it (impound), web it arrived at my shop everything 'dual' was missing, the tow truck driver apparently thought he needed it more than he thought I did. Bastard. __________________ WHO_DCTC - Wifes 05 Z-71 Build - Now defunct as she decided she wants an Escalade too Cream Puff - LS'd Square - Slow going on the back burner Tripple Threat - 3 Wrecks for the price of one build thread Project Delongdium - Step-Sons Plastic Clad 2003 Avalanche - DONE and Delivered.



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