New GP harness, looong run time

[vegas39]

Hey all. So I just replaced my glow plug harness with a custom made one from eBay and now my wait time is really long and I have no more afterglow.
I tried another good controller and it does the same thing.
This harness isn't like the original, as the original had a large wire in the loom and branched off to a smaller wire size at the connectors.
This new harness has individual small wires that go directly to the controller.
So if someone knows how these controllers work, I'd be very interested to know why the timing is so much longer now. Thanks!

 

[snicklas]

The solid state 7.3 style controller, the one that bolts to the intake by the CDR, not the 6.9 style that is threaded into the rear of the drivers head, is a current draw/voltage drop measurement.

With all "good" factory wiring and ZD-9 glow plugs, with a clod engine, the controller will turn on the plugs, and run them for ~8-15 seconds, depending on temperature. The way it determines the time, it measures the voltage drop across the Z-Strip Resistor on the controller. As the glow plugs heat up, their resistance increases, drawing less current, changing the drop across the Z-Strip. Once this drop gets to a certain point, the controller start to cycle the plugs, keeping the hot, but not overheating them. This is the afterglow click you hear.

So the opposite problem from what you are having, when a plug(s) fail, the entire system draws less current (mimicking warm plugs), causing the glow plug controller cycle to shorten (think of the WTS time on a warm engine) or just immediately go to afterglow, because the overall resistance of the circuit has been reduced.

In your case, it sounds like this new harness has increased the overall resistance of the circuit. So this makes it think it 50 below and needs to run the plugs for a loooooong time to start the truck. Or another way to think of it, the controller "thinks" it's running 12 plugs, not 8...... which equals a longer cycle, instead of it running 5 or 6 and "thinking" the engine is warm.......

 

[vegas39]

That's interesting and too bad. This harness is really nice, braided wire jacket and big plastic connectors that slide over the gp's.
So am I stuck with how it is? Any mods I can do to shorten the wait time?

 

[Thewespaul]

Push button for manual control will fix that right up