GP Controller
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From: Norfolk
GP Controller
As some of you know I have posted a couple of threads in the last 2 days trying to fix this 7.3 correctly. What I would like to know now is if I pull all the wires off the GP's,(and insulate them so they dont short out), can I power up the controller so I can test the WTS circuit and the fuel heater circuit without harming the controller? Once again thanx to all those who have already helped me, and to those still willing to do so!!!!
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From: Timmins, Ontario, Canada
Yes, also, fuel heater is independant of the controller. Several circuits draw power off the +12V in start/run post of the relay that sits on top of the controller, but they aren't dependant on the controller's functions.
The WTS light wire is the blue one with the snap-connector on it.
The WTS light wire is the blue one with the snap-connector on it.
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From: Norfolk
Many thanks oreo & northern. I know that the wire is the snap connector out of the controller, what I dont know is that is that wire suppose to be a hot wire, or a switched ground for the amount of time the WTS light is on. On the diagram for the 6.9 GP harness it shows the fuel heater in line after the WTS light. I havent found the 7.3 schematic yet. If anyone has 1, would you please post it! Thanx again for everyone's help!!!
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From: Timmins, Ontario, Canada
I've got the Ford manual for 1994 7.3L style, but the book is at home so I'll have to scan the page and post when I get home! I think it will be much closer to the wiring you're looking for.
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From: Norfolk
Ok I have the WTS light now working, just seemed to be a bad connection at the snap connector. Now to under the dash, because I only have power in the run position to the controller, not on the start side of the IS. But then again the under dash area is hacked to death, so more tracing and soldering.
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From: Timmins, Ontario, Canada
Schematics for cold start system 1994 7.3L from the Ford manual.
I tried to post the warning indicators system but its rejecting it for some reason... All is says anyway is that +12V come from fuse 17 in the cab to the WTS light and the other side is grounded out by the controller to light the indicator.
If the pics aren't big enough check out my gallery!
I tried to post the warning indicators system but its rejecting it for some reason... All is says anyway is that +12V come from fuse 17 in the cab to the WTS light and the other side is grounded out by the controller to light the indicator.
If the pics aren't big enough check out my gallery!
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From: Norfolk
Many thanks Northern for the schematics. It has helped. I seem to have all the GP controller & fuel solenoids working. It has been a nightmare with all the hacked wires, but persistance pays off. Off to the next thing, does anyone know what the sending unit is in the fuel filter/heater? I see the wire on the bottom for the water in fuel light, which is working, cause there was water in the filter, and the light was on. The sending unit has 12 volts to it, but dont they usually run off a ground? If I hook it up, I lose power to the GP controller, diconnect it and everything works again. Any ideas guys?
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From: Timmins, Ontario, Canada
NP bluesman. I scanned a copy of the 'Warning Indicators" circuit as well but it wouldn't post to my gallery for some reason...
The sender is a pressure switch for the plugged filter indicator. All the indicators are grounding circuits, except for the Water circuit (which still grounds through a relay). This does mean that there should be 12V at the sender, but it should be 12V from the lamp in the dash not from the GP relay... disconnect it and short it to ground, and see if the "FUEL FILTER" indicator lights. It shouldn't have any connection to the GP system.
The other wires to the filter are the power supply to the heater, which should also be independent of the GP relay (as shown in the schematic above), and the Water-In Fuel indicator.
I'll try from another computer to upload the schematic for the Warning Indicators.
Electrical stuff is the kind of thing that seems impossible but like you said, persistence, its not bad but it takes time and trial and error!
The sender is a pressure switch for the plugged filter indicator. All the indicators are grounding circuits, except for the Water circuit (which still grounds through a relay). This does mean that there should be 12V at the sender, but it should be 12V from the lamp in the dash not from the GP relay... disconnect it and short it to ground, and see if the "FUEL FILTER" indicator lights. It shouldn't have any connection to the GP system.
The other wires to the filter are the power supply to the heater, which should also be independent of the GP relay (as shown in the schematic above), and the Water-In Fuel indicator.
I'll try from another computer to upload the schematic for the Warning Indicators.
Electrical stuff is the kind of thing that seems impossible but like you said, persistence, its not bad but it takes time and trial and error!
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From: Norfolk
Hey northern, I dont see any plugged filter light in the dash, only the WTS & Water in fuel lights. Unless its up on the cluster with a burnt bulb, I have nothing. Also am trying to find a wire off the IS for the start side to run the GP circuit. I have 1 hooked from the start side to fuel solenoids, but cant tap into that for the starter. I had power to hot wire for the starter solenoid, but now have nothing. Will keep banging away at it, will keep ya updated!!!
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From: Norfolk
Ok, here I go deeper in the pool,lmao. I just undid the steering column, and the connector to the IS has been terribly spliced together. It seems the PO has had serious elec. issues. I have lost power out of the IS to the starter solenoid, does anyone have a clue as to what wire would that be. Also, does someone have the fuse block layout. There is no #s on it, nor a cover to tell me which ones go where. They had a small jumper from 1 fuse to another, which I pulled out, just because the plastic was melting away, am thinking that could have been my starter solenoid hot wire. Might have to go to the JY to replace the fuse block, this 1s in terrible shape. Thanx again to all of you who have helped, am making small leaps an bounds, but am headed in the right direction!!!
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From: Timmins, Ontario, Canada
Wow... its a real mess eh?
Maybe 89 didn't have a plugged filter light... it should be the unit sticking out the side of the filter head that looks like this:
Based on your fuse setup, maybe the power feed to the indicator is fried...
At any rate, here's some schematics that'll help, including the fuse block layout (keep in mind this is for 94 so it may be a little different):
Warning Indicators:
Starting System (2 Pages):
Dash Fuse Block:
Engine Compartment Fuse Box:
Maybe 89 didn't have a plugged filter light... it should be the unit sticking out the side of the filter head that looks like this:
Based on your fuse setup, maybe the power feed to the indicator is fried...
At any rate, here's some schematics that'll help, including the fuse block layout (keep in mind this is for 94 so it may be a little different):
Warning Indicators:
Starting System (2 Pages):
Dash Fuse Block:
Engine Compartment Fuse Box:
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From: Timmins, Ontario, Canada
Sorry, I'm a different body style for that... and my 1990 isn't diesel. The pressure switch isn't connected to anything else though, so it won't have any effect on the rest of the truck. Leaving it off for now might simplify your other problems until they are resolved!
Note for the above... it should be the Red/Light Blue Stripe wire from the ignition switch, to the clutch pedal position switch, to the starter relay on the fender. Also, both the GP relay and the FSS solenoid should be powered both in start and run (might just be the wording above, but it helps to be extra clear!).
Note for the above... it should be the Red/Light Blue Stripe wire from the ignition switch, to the clutch pedal position switch, to the starter relay on the fender. Also, both the GP relay and the FSS solenoid should be powered both in start and run (might just be the wording above, but it helps to be extra clear!).