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Thursday, November 26, 2015

Identifying the neutral clutch safety switch.


This is the neutral clutch safety switch on the F250 (1987) from the video the fellow did on bypassing the switch. It is clearly a switch that takes only one fuse, and it's just below the emergency brake release handle.


I can find nothing even remotely similar on my truck.

However, using a diagram I located what I think is the clutch safety switch.  It is not on the left side of the floorboard, but the far right. It has four fuse slots, and four wires. Two are red, two are green.

this white plug connects to the black plug below.


The black plug is mounted on a rod that connects to a piston on the brake column, which depresses when you push the clutch in. This switch seems to match the diagram below although it's not exact.






truck.


My plan is to go ahead tomorrow and try putting a fuse in first the white plug, and if that doesn't work then see if it will fit in the black one. I am fumbling my way here , but I don't want to have the truck hauled down to the shop I go to on a wrecker just to ask them to identify the switch to me. I already know they won't help me bypass it.

15 comments:

  1. In my 1988 ford 7.3 diesel, I read the "fixes" and ended up taking some #14 or #12 house wire bent in a U shape and stuffed the stripped ends into the connector, creating a jumper. To be safe I electrical taped it in place so it couldn't come out. That was about 2 years ago, so the details (like wire color) are gone.

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  2. That certainly is different from standard. As yours is a diesel spec truck it may have a different wiring loom. I think I would try and identify the hot lead in that plug first. With the ignition key in the run position, put your multi-meter on 12 volt dc, one probe on a good ground, then with the other probe check each of the 6 leads in the plug til you read 12 volts on your meter. It is likely one of the two red wires. The next step is to identify which of the other leads is supposed to complete the circuit to allow the starter to be energized when you turn the key to start.

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  3. That's what several people have advised. My problem is more finding the right switch. I can't figure out why his 1987 and my 1988 apparently have a completely different type of switch in a different place. If I do have the right switch, I have four wires and four fuse slots. He has only two, both red wires. When you say the connector, you mean the piece that unplugs, on the female section of the switch itself?

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    1. Harry, a quick web search for 1988 Ford F250 diesel wiring diagram provides:
      http://www.autozone.com/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f8038ecd6
      See figure 5 for the diesel engine diagram. Hard to make heads or tails of it. If you look at the other figures you can decipher that the truck obviously came with multiple engine options as well as California Specific options and each has a different wiring loom. This explains why your plug/connector is different. If yours has/had an AC, the clutch start cut out switch also controls the AC clutch so that when you start the engine with the AC on you are not also spinning the AC compressor. So that is why you likely have extra wires on that plug/connector. It is a mater of finding out what each of the wires on that plug/connector of yours goes to. I have been lucky at NAPA, they often can provide the info if you give them the serial number of the vehicle.

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    2. Michael, I got it going today, putting in the connecting wire into the switch where the two red wires went in worked great, it fired right up. I still have no idea what the two green wires I disconnected were for, I will probably find out when the brakes fail going down a steep mountain road or the truck explodes in town and causes a terrorist alert.

      Thanks for the link to the diagram. I am going to start trying to learn about the truck as much as I can so I can do more of my own repairs, since nobody wants to work on it up here anymore.

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    3. Well congratulations, you have successfully solved the problem. I bet it feels good to. Get yourself one of the two manuals I linked before. They will help a lot next time around. They will have all the correct wiring diagrams and all the wires are color coded so you can identify them. I used to be afraid of these dark mysteries too, but eventually I figured it out. Sometimes It takes a couple of tries but you can sort it out. And then you are not at the mercy of other perhaps not so honest folk to keep your old truck running.

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  4. Hey Harry,

    (captaincrunch)

    I know a mechanic in down here that would by pass that switch for you. One thought Harry. If your not successful. Maybe talk to the Ford Dealer one county over and get a year warrenty on the parts and labor, including the tow fee.
    Go through the service writer and the service manager and make sure you get it in writing
    I worked at several truck shops so I know how the game is played in the service industry.

    One thought too, your truck does not have the correct part because the part was not in stock, so the tech (acting on the advice of the shop foreman) installed a clutch safety switch from another year or model and jury rigged it to work, therefore causing a premature failure of the part that was not designed for that specific truck in the first place.

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    1. The other possibility is this. My truck was wired to pull a full sized horse or cattle trailer. It has a reinforced bed (welded I beams) and a pental hook for a trailer in the bed. It has an aftermarket switch wired in to hook up the brake lights and all on the cattle trailer.

      I am just going to have the truck towed in tomorrow, have them put a new brake booster cylinder in it, which it needs, get an oil change, and have them put a new switch in it. I know the switch will crap out in a month or so, but if I have the mechanic at the shop tie a tag on the wires I need to cut and splice, then I can fix it myself.

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  5. My 'fix' was done under the dash. If you are jumpering the 'input' to the switch, it shouldn't matter what kind of switch or where the actual switch is located. Jumper replaces the switch. The connecter remains unplugged. My jumper was a single wire. I used Red if I recall.

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    1. What exactly is a "Jumper." Is it just splicing two wires together?

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  6. Yeah, one wire likely brings power to the switch, and when you push the clutch in the switch connects that to a second wire, completing the circuit. (I say likely because sometimes they use a ground circuit to do things, just to make it more fun) All you have to do is figure out *which* two wires, and make just about anything that will carry current to connect them together. House wire (single strand) is fine. Automotive wire with or without crimped on connectors. You can even use one of the evil blue "scotchloc" connectors that clips into the wires. I swear they breed though...If you can find a "power wire" with a multi meter, or test light, make a connection between that wire, and each of the others in turn until it works.

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    1. I bought some number 14 gauge auto wire and I made a horseshoe shape out of it. I stripped off a little of the insulation on both ends and twisted the exposed wires together. When I went to plug the fuse into the switch, I found there was no slot for a fuse, only a thing like a ten pin connector, with two green wires and two red wires. I put my little contraption in the switch where the two red wires came in, as people said to do, and lo! The truck fired right up. I idled it for about half an hour, no problems. Turned it off, it turned right back on. Success! Of course, I didn't do anything with the two green wires but the lights and such seem to be working ok.....

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  7. This won't help at all, but back in the 70s when I worked at an auto parts store, I was always finding that cars didn't have the "correct" part installed. I was always going out to their cars with my parts catalog to try to see which part was actually used.

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    1. Charlie, the guy who had my truck before me used it to haul cattle out in Montana. He had the bed reinforced with welded i beams, and built a new wiring harness because he hauled huge cattle trailers (my truck has a massive pental hook and plate in the bed), and I guess in doing all that he African Engineered a whole new wiring system. But I did find the switch and by doing what people told me to do I successfully bypassed that wretched and useless switch, and the truck is running fine now! I am not auto mechanic, most of the things I have learned to do over the years are the result of having to to them myself for lack of options. The internet really helped me out on this, lots of knowledgeable friends took the time to help me and I appreciate you guys.

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  8. The other 2 wires are probably for the cruise control function.

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