Exterior Fuse Box where is it???????

Hummer H1 and Military Humvee topics
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butchh
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Joined: Thu 05 Feb , 2009 10:36 am

Exterior Fuse Box where is it???????

Post by butchh » Fri 12 Oct , 2012 10:31 am

I have a 1996 H1 and am trying to troubleshoot my P1643 code and part of it in the manueal is to check the exterior fuse box. I have spent a couple days trying to find it. Does anyone know where it is?? I have a H1,1996 wagon. Any help would be appreicated.

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1997HMCS
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Re: Exterior Fuse Box where is it???????

Post by 1997HMCS » Fri 12 Oct , 2012 2:42 pm

I don't think pre 1999s have any sort of external fuse box except for the CTIS relays., but I'm not 100% positive on the 1996.

butchh
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Re: Exterior Fuse Box where is it???????

Post by butchh » Sun 14 Oct , 2012 12:43 pm

Thanks for the input. I think you are right, found what you said, but can't find anythink else. Again thanks!!! Still trying to work through the P1643 code and the wiring diagram and trying to understand, plus finding the errors with the manual and digrams.

Have a great day!!

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GreenMeanie
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hummer_info: 1997 HMC4 H296 Green
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Re: Exterior Fuse Box where is it???????

Post by GreenMeanie » Sat 20 Oct , 2012 3:02 pm

Its possible they meant the main distribution box which is behind the regular fuse panel under the dash on the firewall. That is where all the relays mega fuses are for the truck. Pia to get to because of all the wires there. Somehow i don't feel that is what you are looking for. Nothing on the outside or under the hood that i know of other than a junction block which could be the culprit. The B positive to your glow plugs runs from there!!
On the 97 there is black and orange wires going to the wait bulb. Orange is positive from the glow plugs and black carries the glow plug signal to the PCM on pin BRD7 which then the PCM controls the light by switching the ground path. You are correct, the manual does not say what pin it is switched on. Im a 97.
It may be different on the 96. I don't know!!
I would say either the ground side of the lamp is faulty or there is a break in the black wire from the PCM to the lamp or even the lamp itself could be blown.
There is also a possible fusable link from the B positive feeding the glow plug controller at the junction block which i believe to be on the drivers side under the hood where the big wires go in below the ctis valve body. There are several connections here and they are famous for getting corroded because there is a lot of dirt and grime that gets into this area.
When i first got my truck it was the first thing i did was to clean all the contacts there. 2 bolts hold all the eye connections to the 2 posts. There are ussualy plastic thumb insulator wheels on top of the posts.
So the therory. You should be able to connect a meter with the truck off and get 12v at the glow plug controller on the b positive wire coming from the junction box. If not the fusable link in the wire is gone or the connection at the junction is faulty. Check for power at the junction block. Chances are you will have power here or your truck would not work.
1997 HMC4 H296 G10 1of35 in the world ,110,000 miles and no cracks yet, HWY speed 84mph & 242 still good, custom PMD, custom overhead console, custom roof rack, custom brushgaurd and custom stereo.
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butchh
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Re: Exterior Fuse Box where is it???????

Post by butchh » Thu 25 Oct , 2012 1:09 pm

Hello GreenMeanie,

Thanks for the input, I appreciate it. You are right the wire color off the wait light is black and orange. But when it connects to the main harness it turns orange--to blue, black --stays black. I checked all the other stuff you had menitoned looks ok. The one thing that has made my life a little easer is that I have the wiring digrams for the H1, it is much more correc than the information in the manual.

I think I am close on getting this figured out, I also know what each of the connectors going to the PCM are and how to identify them for checking pins and there connections.

Thanks again, all inputs help when trying to figure things out.

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