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He does have the clutch switch, but it isn't wired in or has failed as it'll start with the clutch in any position. In fact, it'll start in any gear, so the NSS is bypassed as well.
I put my DVM on as you suggested for the LED, and only saw 5 volts when it wouldn't crank. But, that was with the wire off the solenoid and the DVM has fairly high impedance so it could be a false reading. In any event, I'm in backtrack mode.
5 volts with the impedance of a DVM is essentially no load on the system. 5 volts is not enough to activate the relay, and if you connect it and try, I'll wager you see 0 volts.
More specifically, an incandescent test light to ensure it pulls a bit of current. And I don't have one since I broke the last one. Guess it is time to make another - especially since I tried to test the trailer connector and remembered why you want a light and not a DVM for that.
But, the relay has a really good ground - I'm sure of that. I sanded the fender where the relay mounts to get to bare metal, and coated that with the anti-seize. And, I made sure the screws are clean and tight.
He does have the clutch switch, but it isn't wired in or has failed as it'll start with the clutch in any position. In fact, it'll start in any gear, so the NSS is bypassed as well....
I don't think there is a neutral safety switch on the manual trannies. That's what the clutch safety switch is for. I know that my '85 would start in any gear, as long as the clutch was pushed in. Eliminate that and there's nothing to keep you from starting in gear (which I actually do pretty frequently when rockcrawling).
Ok guys, I need help getting my head around the fuel pump relay wiring. Basically, I need those of you who have 460's to explain where the oil pressure switch is, both physically and electrically.
In this excerpt from the 1986 EVTM, which is pretty well identical to the '85 version that I have in hard copy, power comes from the fuse box to connector C325, then to the oil pressure switch, then through C143 and on to the fuel pump relay's coil.
And the actual 1985 schematics show virtually the same thing, although the second connector is C136, although both C143 and C136 are single-pin connectors close to the ignition module, so that may be just a change in numbering from '85 to '86. However, Big Blue's wiring is not this way. I've unwrapped the wiring harness and power does come from Fuse 18 to C325, but instead of diverting to the oil pressure switch it just goes through the single-pin connector and right on to the fuel pump relay as suggested by my alterations on this schematic. And, there are no hacks to the wiring. It was all covered in the original electrical tape, and there are no splices nor joints.
And, here's a picture for proof. The 4-pin connector in the middle of the picture is C325 and you can see the red/yellow wire coming in from the fuse on the right, and the red/yellow wire coming out on the left and going to the single-pin connector. (Note that Big Blue may be a transition truck between 1985 wiring and 1986 wiring as one harness has a red/yellow hash wire as the 1985 schematic and EVTM show, and the other harness has a red/yellow stripe wire which is consistent with the 1986 EVTM.)
So, HELP! Where's the oil pressure switch supposed to be? And how is it wired on your trucks?
Oil pressure switch was on the back of the engine teed in with the oil pressure gauge sender. It was a very small switch with a two wire connector. See picture for location. I had already installed the later dash, so instead of the big domed sender I had the later "sender" (actually a NO switch that closes to indicate oil pressure).
Ok, so it does go on the back of the engine. I'll have to put two tees there to feed the factory gauge, the aftermarket gauge, and the switch.
Now, where did the wire to the switch come from? Was it part of the harness that feeds the distributor, coil, etc? Or, was it from somewhere else? And, was your engine wired like the EVTM shows?
Mine was wired exactly as my EVTM shows, fuse #18 fed it (keep in mind there is no firewall connector on these trucks) and if I remember it was a separate harness that ran up the inside of the left valve cover. Basically plugged into the fuel pump relay and had a single connector from the resistance wire that ran across over the radiator area from the starter relay area. The inertia switch wiring ran in that same piece, just two wires, yellow and pink with black. Here is where they ran back to the switch, it may have been with the gauge sender wiring. I seem to recall the DS-II was a different harness.
Red highlights the wiring to the oil pressure switch and gauge sender.
Ok, thanks. I think what I'm going to do, assuming I don't find the oil pressure switch wiring, and I doubt I will, is to replace the single-pin connector with a two-pin one, and loop to the switch and back. The oil pressure wire runs with the DS-II wires and is going there anyway, so I might as well run these with it.
You don't happen to have an extra harness, hacked or not, that would have the red/yellow wire in it? I have another harness, but it is for a 351HO so doubt it has the right wire, although I'll look tomorrow.
Bill - You are gonna let a little Nor'easter bother you? Just told Janey last night that I'm glad we no longer live in the Philly area. That's gotta be getting old! I hope you don't have any problems from it.
Subford - Thanks. Unfortunately your schematic is essentially the same as the two I posted, meaning none of them are how the truck is wired. However, the picture of the switch does help as I see the adapter Ford used to put two components on one port. I think I may have one of those from a 351W, although that one may be just an extender w/o the second port.
Wiring has definitely been hacked.
Do YOU see shrink tubing on any other connector of any stock harness?
Subford has a good picture of the pressure switch and the connector.
BTW, I did find that trailer harness but it has an F5 engineering # so it must be for one of the Powerstroke's I've worked on.
I'll send it along.
Jim - Are you talking about where I have the arrow pointing to what I thought is the single-pin connector? You are thinking the loop to the oil pressure switch was cut out and shrink tubing used on the connection? I assumed that was the stock covering for the connector, but will pull it apart and see what's under there.
By the way, the wire ties are mine to hold the harnesses in their original positions. I pulled off what I thought was the original electrical tape and that connector/connection was buried in the middle.
I've unwrapped the wiring harness and power does come from Fuse 18 to C325, but instead of diverting to the oil pressure switch it just goes through the single-pin connector and right on to the fuel pump relay as suggested by my alterations on this schematic. And, there are no hacks to the wiring. It was all covered in the original electrical tape, and there are no splices nor joints.
