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I've got a 99 f250 super duty 6.8l and have a couple ?'s first on the front of the fuse box under the hood there's a small deal with a couple wires plugged into it, it seems like it is supposed to clip into the front of the fuse box, what is it and what does it do? Next there's a secondary relay box beside the main fuse box, again under the hood, and it has places for 2 relays, the front relay is there and the rear isn't, what are they for? Also it has a jet performance module, can I get another programmer and tune it as well? I want to make the transmission shift firmer.
What is the deal in my hand? Comes from harness under fuse box on femder well
Last edited by Jonnyih; Mar 25, 2016 at 01:00 AM.
Reason: To add pics
Do you have the manual that comes in the glove box? These have all the relay and fuse locations. Can you upload a picture of the wires you are talking about?
I've added pictures, that's my main concern since it is broken and has a bad wire, the single relay isn't so much a concern and I found the other relay box and due to corrosion I had to wire 2 new relays in and take box out, now my 4x4 works and good thing because I needed it today in Northeast iowa, I didn't get manual with truck, and thanks for the info on the tuner, so my main concern is figuring out what that sensor or whatever it is...is.... then to see if I should order new one or leave it alone, but not knowing what it is makes it hard to go buy a new one
I know for sure that it's not that, I got truck with bad fuel pump and gut had intake off so he could pour gas in intake to diagnose it, I had to put that back on and plug air temp back in, look in front and under fuse box, it comes out of big harness on fender well and it's the only 3 wires in that branch, by the fact that the harness is only so long it seems to me like it attaches to the fuse box or within a foot of it, thanks
Is the Intake Air Temp sensor in the intake piping plugged in? Tomorrow I will take a look at mine.
I had to clean up a lot of messes on this truck, pulled all this out of truck, 5 went from battery and into cab and 2 wires all the way to trailer plug, took it all off and hooked things up right, 220,000 miles on it and she goes good
Found that the mysterious wiring + sensor is for the brake fluid reservoir, there's no leaks and no lights on to say something is wrong. What does this sense?
It's a fluid level sensor, this is what alerts you when you're low on brake fluid. If it's not plugged in, then what is screwed into your master cylinder where the sensor belongs?
Means you have no warning light that could save your life. I wouldn't skimp if it were me.
Agreed, thanks everyone for the help! Got truck cheep and just getting the previous owners messes all cleaned up, v-10 with 220,000 miles and I've put the last 1100 on it and it's been a strong truck. This is by far the best go-2 site for anything ford and I've used it for all my trucks at some point or another
The sensor works through the plastic, so you don't need to worry about brake fluid leaking out when you get out the remaining bits of the old sensor. unless the reservoir has been broken...
