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Replaced the controller on this ‘91 350 7.3 over a decade ago. Again having an issue. Slow to initiate the timing, then erratic timing of the distinct clicking sound, interruptions, fast timing, and some normal. The amp gauge does not report the ticks as usual. Am I correct in assuming the relay itself is responsible for the clicking, and perhaps only the relay requires replacing. Anyone with similar experience or knowledge of the components involved have any suggestions or solutions? Thank you.
Replaced the controller on this ‘91 350 7.3 over a decade ago. Again having an issue. Slow to initiate the timing, then erratic timing of the distinct clicking sound, interruptions, fast timing, and some normal. The amp gauge does not report the ticks as usual. Am I correct in assuming the relay itself is responsible for the clicking, and perhaps only the relay requires replacing. Anyone with similar experience or knowledge of the components involved have any suggestions or solutions? Thank you.
changed the relay, checked plug resistance (good), reconnected as it was. Did not do the clicking but made a slightly sizzling sound. Started the truck, but then looked like smoke. Shut the whole thing down. Controller got hot. Decided to go with a 4 post relay, and in cab momentary switch. Now the problem. The two yellow wires which had gone to the top hot side do not have continuous 12 volts. The brown wires, which were connected to the lower end of the metal folded strip does. Yellow no continuity to starter relay brown does. Both have continuity to an unconnected glow plug lead. Has to be a short to ground somewhere on the yellow lines. Can’t connect anything until this is sorted. Anyone with experience? Appears completely backward, and not a fooled around with truck wiring under the hood.
I will examine in detail, however every wire I can identify goes into a loom, then directly into another until it’s termination. Looking for a wiring diagram, no factory service manual, and diesel info isn’t as easy to locate as gas.
Ford used fuseable wire on the glowplug harnesses. Sounds like it did its job and saved ya from a potential fire. You’re going to have to either repair or replace the GP harness. Brown is the GP harness, yellow is the 12v source from battery. You can use a brand new GP harness from a 6.0 ford off amazon for like $25 (I just did) with a little modification. You can also consolidate the 2x yellow 10 awg to a single wire. I would step to 8 awg for that. I’m adding a photo of the GP harness on mine with wires attached so you have a reference on how to reconnect yours when done in case your forgot to take a photo for yourself. Also make sure you ground to motor or chassis, not direct to battery, otherwise your ignition will no longer turn the truck off.
I would bet the two yellow wires are also protected by a fusible link which needs to be accounted for if rewiring it.
Something fried at the relay, I meggared the wiring harness, all good. Never cared for the OEM dinosaur relay so wired a continuous duty 4 post relay and a momentary cab button on the left hand side of the column. It works well, learning the appropriate duration for engine cold temps, and I can hold it for a few seconds after some initial firing if helpful. I think the OEM might have done this as well. Information on replacement harness availability and rewiring the controller power is something I will keep on hand for this aging but hard working truck. I have a 2018 f-150 5.0 with the 10 speed that will never see 34 years. Thanks so much for taking the time to share your experiences. Also got a new IP, now off to diesel shop for some appropriate timing.
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