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Cargo Master
Joined: Aug 2004
Posts: 3,455
Likes: 8
From: Williams Lake B.C.
Ive asked before?
Ive asked before and either nobody knew or I missed the answer.
What are the relays under the hood for?
I have 3 black boxes with relays in them?
There are NO fuses in the boxes.
I cant find the info in my owners manual.
2002 F-350 7.3
What are the relays under the hood for?
I have 3 black boxes with relays in them?
There are NO fuses in the boxes.
I cant find the info in my owners manual.
2002 F-350 7.3
Snowboard season cometh..
Joined: Jan 2006
Posts: 5,406
Likes: 1
From: Gulf Coast of Florida
I just went out and took these pictures. Keep in mind that my truck is a late-99, not an '02.
Covers closed:
Covers opened:
I've never fully decoded my VIN, but as you can see on mine, one of the smaller boxes has 2 relays, the other small one has none, & (thankfully!! HAHA) the big box is full of goodies! My truck did come standard with the normal 7 & 4 pin hookups by the hitch, but I think all Super Duty trucks come that way (but of course could be wrong). Hope this helps, at least for reference.
Covers closed:
Covers opened:
I've never fully decoded my VIN, but as you can see on mine, one of the smaller boxes has 2 relays, the other small one has none, & (thankfully!! HAHA) the big box is full of goodies! My truck did come standard with the normal 7 & 4 pin hookups by the hitch, but I think all Super Duty trucks come that way (but of course could be wrong). Hope this helps, at least for reference.
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
I do not have the 2 relay receptacles closer to the fire wall nor did my truck come with the tow package, no round 7 pin connector. I had to add a relay (I used a starter solenoid that is in upper right corner of pic) for trailer battery charge.
I do however have the 2 relays for ESOF. They are relay numbers 41 & 42. Peter, you are right about ESOF relays.
I do however have the 2 relays for ESOF. They are relay numbers 41 & 42. Peter, you are right about ESOF relays.
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Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
I'd have to look, but from what I remember, those 2 relays come with the little plug for a brake box, so one probably energizes the brake box circuit and the other probably handles the trailer hot wire for charging, trailer lights, accessories. I've got the same 2 relays on my 02 and I don't have ESOF.
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Joined: Oct 2007
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From: Farmington, Minnesota
I do not have the 2 relay receptacles closer to the fire wall nor did my truck come with the tow package, no round 7 pin connector. I had to add a relay (I used a starter solenoid that is in upper right corner of pic) for trailer battery charge.
I do however have the 2 relays for ESOF. They are relay numbers 41 & 42. Peter, you are right about ESOF relays.
I do however have the 2 relays for ESOF. They are relay numbers 41 & 42. Peter, you are right about ESOF relays.
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
That's what I had to do. The seven pin connector was put in by the dealer I bought a 5er from but since I didn't have the tow package they didn't bother with the battery charge circuit. Nor did they bother to tell me.
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
That's because none of those pics are of an 02. Mine doesn't look like that either. We don't have the big plastic box under there. Just one of those little ones right up against the fender that holds 2 relays and nothing more.
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
Wow. I don't have that many. I've just got the one right next to the fender. I thought there was only 2 relays under there, but maybe there are 3 like in your pic. I have no idea what the other 2 are for. Maybe one of them is an ESOF if you've got that.