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Wanted to ask if anyone could upload any EVTM scans of the E-Series 7.3 IDI manual regarding the glowplug controller diagram(s) and starting system. I have an '89 van engine going into a '93 truck and the engine harness on the van engine has two extra wires at the connector that the truck doesn't have but is missing the ring terminal on the starter solenoid that the truck does have. I have ordered an EVTM but ideally if someone could post the glowplug/starting system wiring diagrams it would be greatly appreciated.
COPY PASTED FROM MY BUILD THREAD INTO THIS FORUM FOR THIS QUESTION SPECIFICALLY:
Currently in a bit of a dilemma, I have opted to use the '89 van engine harness because it is in much better shape all around, and it lines up nicely with the engine itself as opposed to the '93 truck harness. My current issues resides in connector for where the harness connects to the connector right by the underhood fuse panel. I extended the wires for the connector leaving the fuse panel to be able to reach the van engine connector (it is in a dif location than the truck connector), which was a necessary step regardless because the wiring looked a little dicey. Anyways, I noticed that both truck/van harnesses use a 12 pin connector, but the van uses all 12 pins (the extra pins are one red wire and one black wire) whereas the truck only uses 10 of the 12 and has two empty slots. Conversely, the truck has a little two wire ring terminal that mounts on the starter solenoid stud. My assumption is that the difference in these harnesses is where the glowplugs, cold idle solenoid, and IP receive power from(?) Am I better off just using the truck harness??? Please advise, I will put pictures below:
Truck Engine Harness Connector - 10/12 pins used
Truck Engine Harness 2-Wire Ring Terminal going to starter solenoid
Van Engine Harness - 12/12 pins used - red wire and black wire on the right
It's not missing anything. The 12 pins on the van harness have the two fat yellow glow plug power wires going through it. Your '93 has those separate (ring terminal) since trucks melted those connectors.
This should work as-is, just run that ring terminal to where the yellow wires land on the glow plug controller.
Awesome, thank you so much. I realized after I had posted it that it was infact the yellow wires that were different, not the red/black. Thank you for the reference thread as well, that is very helpful. I am curious as to why the truck would melt those connectors when a van wouldn't but I suppose that's a different question entirely. I ended up using the truck harness since I didn't have any proper gauge wire on site to do as you suggested, but it's good to know that I can modify if needed.
My bad, don't take "truck" literally. Melting could happen any time the plug wires ran through that connector. Keep a healthy glow plug system and you'll be fine. Remember Ohms law - the glow plugs have a resistance, albeit small (less than 2 ohms). A short (0 ohms) is what will kill the connector. The normal ~100A glow plug circuit now pulls infinite, and you get a crispy connector.
I see, they had an issue with the wires running thru there and ultimately decided to just run it from the solenoid on the fender. I just revamped my GP system. New Motorcraft ZD-29s as I have been unable to find any ZD-9s. I audibly hear the glowplug relay click on and off as it should (no rapid clicking). I have checked my voltage leaving the relay and it is only 7 volts, however this is expected when it is ~100F outside because the resistance would be much higher right?
I'll have the van harness as a spare if I ever need it.
7v is bad. Not in a dangerous way, but like in a weak glow plug way. Without a full 12v there's not much juice getting to the plugs and they're not as hot as they should be.
Check resistance across the glow plug relay terminals when it's active. In all likelihood you just need a new relay.
anything over around 110 degrees engine temps and the glow plugs are turned off.
there may be nothing wrong with the system other than it is hot out.
what i would do is remove the glow plug relay and test it out of truck.
it may be fine, or the contact plates inside may have carbon burn marks on them preventing current passing.
That's what I figured, anything 112 F and over and the cold star solenoid shouldn't activate either. 95 F ambient air temp in HOU plus direct sunlight, engine is pretty toasty. Just in case I will do my due dilligence and take a relay resistance measurement. What kind of a number would signify a good vs. bad relay? I doubt just a couple ohms off will cause much trouble but maybe I am mistaken. I had another relay on there that came with the engine -- swapped to the relay that was on the original truck engine because I was also seeing 7v @ the receiving end. After the swap there was no difference, doesn't mean that BOTH aren't bad but I took it as a good sign. I'll ohm out the plugs too just in case but they are brand new.
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