Won't start - help with clutch switch?

[fields_mj]

I'm having a problem with my truck not wanting to start. Turn the key and nothing happens. Short out the starter relay on the fender and the truck starts fine. I suspect my problem is in the clutch and/or clutch switch. A couple of days ago the clutch pedal bushing finally gave out. This is when my problem started. I was at the station fueling up when it happened. When I got home I checked the fluid level in the reservoir and it was a tad low so I topped it off, and then took a look under the dash only to find that the push rod was nearly separated from the linkage to the clutch pedal. I slid it the rest of the way off and what was left of the plastic bushing fell into my hand. Thankfully the parts store had a couple of them so I went and got a pair of them so I had an extra one on hand. The push rod and bushing are still wanting to slide off the little shaft on the linkage. I suspect that the new bushing didn't liked getting installed in below zero weather, and it may have broken an ear off when I snapped it in. I'm waiting for some warmer weather to try another one. Its not causing any problems with shifting, just starting. For the past two days I've been able to reach down and pulling the push rod over where it should be, and then the switch will actuate allowing me to start the truck. This morning that fix stopped working. No matter how tightly I pulled the push rod over, and how hard I pushed on the clutch, I couldn't get the truck to turn over. I even pulled the switch off of the push rod, and tried actuating it by hand while turning the key. No luck. Thankfully my driveway is relatively level so I just put it in neutral, popped the hood, turned the key on and waited for the GP controller to start cycling then shorted the starter relay out with my handy screw driver to get the truck started so that I could get to work. The screwdriver happens to be teh key to my redneck tailgate lock if that tells you anything about the condition of the truck....

So my question is, can anyone tell me what the pin out is for the switch that's on the push rod for the clutch master cylinder? I would think that there should only be 2 wires, but I'd be wrong. Just like every other automotive electrical connection, there are several wires connected to the switch. I'd like to unplug the connection and put a couple of jumpers in to verify if that my problem is this switch not closing correctly. If so, I will permanently short them so that I don't have to mess with it any more. Now that its -5 outside, I really would like to be able to start it from inside the cab.

Also, electrically speaking, are there any other switches that need to be made in order for the starter circuit to be completed other than the key switch on the column?

For what it’s worth, I’m talking about a ’93 F250 with the standard ZF5 transmission.

Thanks,
Mark

 

[IDIoit]

governmental safety BS!!!
yes its only 2 wires.
i cut the connector off mine, and wired them together.
takes 1 minute with a butt connector, 2 minutes to solder and shrink wrap.

but that didnt cure the same issue i had. i read that it may be my ignition switch, my column was shot, so i bought another, and still didnt cure it.
turns out i have another problem somewhere that i have not tracked down yet.

and i prolly wont until i do a resto.
i wired a button to the solonid.

 

[fields_mj]

governmental safety BS!!!
yes its only 2 wires.
i cut the connector off mine, and wired them together.
takes 1 minute with a butt connector, 2 minutes to solder and shrink wrap.

but that didnt cure the same issue i had. i read that it may be my ignition switch, my column was shot, so i bought another, and still didnt cure it.
turns out i have another problem somewhere that i have not tracked down yet.

and i prolly wont until i do a resto.
i wired a button to the solonid.

That's what I figured. Any suggestion on how I figure out which two wires it is or what all the others do?

I'd thought about wiring it to another button, but I already have a button to overide the GP controller, one for a wrap heater on the fuel filter, and one for a water injection system to help clean things out when I'm running WMO. The dash looks like an angry wood ****** got stuck inside, and I don't have a whole lot of room left for another push button .

 

[Bashby]

You wamt the two red wires with the blue stripe on them.

 

[fields_mj]

Interesting, I don't remember seeing two red wires. Then again it was dark, 5 below, and I was in a hurry so odds are I just wasn't looking very well. I'll take another look and if there aren't 2 red wires, I'll snap a pick of what's there.

Thanks!!!

 

[cpdenton]

One other way of doing this easily...on an OBS truck.

All trucks have this wiring harness already installed. On an automatic truck, it is up out of the way above the pedal assembly. It also has a jumper plugged in to the end of the connector. This jumper should be found on all OBS trucks with automatic transmissions. Pick one up at the salvage yard and plug it in and you are starting without pressing the clutch, AND without hacking the wire harness.

He is right about the red/blue wires. Hook the together and you are good to go.

 

[cpdenton]

Picture of the pinout for the connector.

The two on the bottom labeled 32 are the two that need jumped.

Th middle two are the clutch cruise override circuit. The top two are not on diesel trucks.

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[madpogue]

^^^^^ And by the orientation of the connector, the two R/LB wire terminals are the two closest to the firewall.

Keep in mind that if you opt for the jumper plug from an automatic truck as suggested above, you will also have NO cruise interrupt functionality with the clutch. Hit the clutch pedal with the cruise engaged, and the engine will redline before you know it. No biggie if you remember this; just tap the brake pedal first before hitting the clutch, just enough to trip the BOO switch and interrupt the cruise..

 

[madpogue]

^^^^^ And by the orientation of the connector, the two R/LB wire terminals are the two closest to the firewall.

Keep in mind that if you opt for the jumper plug from an automatic truck as suggested above, you will also have NO cruise interrupt functionality with the clutch. Hit the clutch pedal with the cruise engaged, and the engine will redline before you know it. No biggie if you remember this; just tap the brake pedal first before hitting the clutch, just enough to trip the BOO switch and interrupt the cruise.

'Course, if you're having to push the pushrod manually to activate it now, that probably means the pushrod really isn't pushing the clutch master in far enough. So bypassing the switch might just mask the fact that you're not really fully disengaging the clutch. You may not be feeling it, but your clutch may be dragging just a bit with your pedal to the floor. This could wear the clutch prematurely. Does the clutch want to start engaging way low in the pedal travel? You might also want to try revving it way up with the truck in gear and you pedal down (parking brake OFF), see if it starts to creep.

 

[fields_mj]

Thanks for all the help. That did the trick. It was in fact two red wires with blue lines. I just didn't take a close enough look in the wee hours of the morning to remember. Grabed a paperclip in the way out the door last night and cliped a leg off to make a quick jumper. Un hooked the plug and pushed the jumper in and the truck started right up. When it warms up some I'll crimp on some blade connectors.

I'm not worried about the cruise. I don't use it. Unless I'm going up hill, or pulling something, it tends to surge a lot. Been that way since I got it in '09 (almost 100K ago). The clutch master cylinder is getting worn, but it does still disengauge. 2nd gear can be a little fussy getting into at times, but I manage. I had a new clutch kit put in 2 years ago. It was starting to slip a little while pulling a 5K camper. I figured 200K was a pretty good life span for the original. Went with an LUK. Should have gone with a South Bend for pretty much the same money. Oh well. Most of the truck is falling appart, so I'm to the point where I only make the repairs that are needed. I hope to get another 24 months or so out of her before I have to retire her to farm duty. I think the engine will still be okay, but that will likely be about it.

Thanks again for everyone's help on this one!

 

[Robt.Webster]

Not meaning to hijack this thread, but I have a new clutch safety switch that I would like to install. Is it possible to separate the existing switch along the horizontal axis for removal and install the new switch in the same way, or is it necessary to disconnect and remove the linkage? I opened the new switch along the horizontal axis, and it was easily done.

Thanks in advance for any assistance.

 

[79jasper]

Yes. It opens the same way.

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[Robt.Webster]

Yes. It opens the same way.

Sent from my SM-T537R4 using Tapatalk

Thanks for the feedback. Can I changeout the switch this way, or do I need to remove the arm from the clutch pedal?

 

[cpdenton]

No need to remove the clutch rod. Slide the clip on the switch forward(or backwards, I can't remember) then remove the clip from the switch. After that, the switch will slip right off the clutch rod. It has o come off this way, the eyelet on the clutch rod is bigger than the hole in the middle of the switch, no way for it to slip off from the end.