Glow Plug Problem
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Glow Plug Problem
Have '89 7.3. My "Wait to Start" light comes on, but sometimes doesn't cycle. Light stays on for about 10 seconds or more, then goes off, but no clicking. So no start. Then will try again, and light comes, then clicks, and starts. Does this sound like the relay? Hope it's not the controller. I'm afraid one of these times, it won't cycle at all, but don't want to put money in the relay if that's not the problem. I see on other posts, Autozone has it for about $16, but I haven't checked yet.
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From: Nutter Fort, WV
Check the ground wire from the controller.
Make sure it is making a good contact with the engine.
It should be under one of the mounting bolts for the controller/relay on the back of the intake manifold.
Do be careful, there is battery voltage on the battery terminal at all times.
It can make a rather big spark with accidental contact with a wrench.
Make sure it is making a good contact with the engine.
It should be under one of the mounting bolts for the controller/relay on the back of the intake manifold.
Do be careful, there is battery voltage on the battery terminal at all times.
It can make a rather big spark with accidental contact with a wrench.
Last edited by Dave Sponaugle; Mar 3, 2007 at 02:30 PM.
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I didn't get a chance to check the ground wire before I had another problem. I was driving along, went to make a left turn, and truck died. Now the WTS light doesn't come on at all, and truck won't start. Cranked over, but wouldn't fire. Engine was warm, so even if glow plugs didn't work, it should have started. Connections on Relays seem tight, but when key is on, there is no voltage at the ignition terminal on the glow plug relay. i don't know much about diesels, but it acts like it's cranking over with the key off. Any ideas? Going to look closer at it on Saturday.
Post Fiend
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From: Nutter Fort, WV
The back drivers side wire connection on the IP is the fuel shut off solenoid.
Try jumping a wire from the positive terminal of the battery to that terminal to see if it starts.
Over on the passenger side inner fender look for red wires with a lt. green stripe.
That would be the ignition circuit.
There is a fuse-able link in it close to the dip stick area.
Try jumping a wire from the positive terminal of the battery to that terminal to see if it starts.
Over on the passenger side inner fender look for red wires with a lt. green stripe.
That would be the ignition circuit.
There is a fuse-able link in it close to the dip stick area.
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From: Nutter Fort, WV
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That's what I was thinking too. The engine cranks, but it acts like it would if you just jumped the starter relay, with the key off. Plus the fact the WTS light isn't coming on at all. I'm only getting voltage to the glow plug relay at the battery terminal when the key is on. Is there a simple way to check the ignition switch? Where should I test voltage when the key is on?
Also Dave, on the diagram of the fuel filter top, it shows a return line check valve. When I took off the brass fitting, I can blow through it both ways. Is the check valve in the brass fitting or the housing itself? The fuel system always seems like it has to pump up fuel, so have to crank engine longer.
Also Dave, on the diagram of the fuel filter top, it shows a return line check valve. When I took off the brass fitting, I can blow through it both ways. Is the check valve in the brass fitting or the housing itself? The fuel system always seems like it has to pump up fuel, so have to crank engine longer.
Lead Driver
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From: Huntington Indiana
In looking at the wiring diagram. The red-lt grn wire from ignition switch to a commom point and splits off to inst. cluster, fuel line heater and a separate wire with same colors goes to another split point to the #15 fuse 10 amp and #18 fuse a 15amp. The 10 amp fuse goes to the fuel selection switch and the 15 amp goes to inst clstr.
There is a fuseable link located in the red-lt grn circuit. Not sure by the diagram but it is betwween the switch and the controler.
There is a fuseable link located in the red-lt grn circuit. Not sure by the diagram but it is betwween the switch and the controler.
Last edited by bigredtruckmi; Mar 25, 2007 at 07:25 PM.
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Took the ignition switch off a Ranger I'm junking out and although wouldn't bolt to the column, could plug it into wiring to test. Didn't make any difference, so I don't think the problem is in the switch, so will put original back on.
I see there is a red/green stripe wire on the "run" terminal of the switch. I also see there is the same wire on one of the terminals on the injection pump, but when I turn the key to run, there is no voltage at the wire on the injection pump.
My guess is somewhere along the line of the red/green stripe wire, I've lost connection. Unless it is a ground problem somewhere.
Tonight, I also notice a fuel leak around the tank, so I have another problem before I get the first one fixed. I need to check out fuel system anyway as it seems to bleed down between runs, then have to crank it more than I should.
I see there is a red/green stripe wire on the "run" terminal of the switch. I also see there is the same wire on one of the terminals on the injection pump, but when I turn the key to run, there is no voltage at the wire on the injection pump.
My guess is somewhere along the line of the red/green stripe wire, I've lost connection. Unless it is a ground problem somewhere.
Tonight, I also notice a fuel leak around the tank, so I have another problem before I get the first one fixed. I need to check out fuel system anyway as it seems to bleed down between runs, then have to crank it more than I should.
Post Fiend
Joined: Nov 2004
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From: Manitoba
Have you checked the engine harness plug...... mine is on the drivers fender. Just follow the wires to/from engine.
Also ensure the relay you get IS for the GP controller not a starter relay..... The controller relay is usually $40+ cross ref the number from the one on your controller......if it's the right one.
Also ensure the relay you get IS for the GP controller not a starter relay..... The controller relay is usually $40+ cross ref the number from the one on your controller......if it's the right one.
Last edited by PLC7.3; Mar 26, 2007 at 12:16 AM.
Post Fiend
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From: Nutter Fort, WV
cowboy51,
check the chassis harness to engine harness connector, passenger side near the oil dip stick.
Look for signs of heat melting the connector.
Corrosion can cause resistance, the resistance causes heat, the heat deforms the connector till the wires loose contact with each other.
check the chassis harness to engine harness connector, passenger side near the oil dip stick.
Look for signs of heat melting the connector.
Corrosion can cause resistance, the resistance causes heat, the heat deforms the connector till the wires loose contact with each other.
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wiring harness looks OK. Seems tight.
When the key is "on", shouldn't I get 12 volts at the terminal end with the red/green stripe wire at the injection pump? I'm not getting any.
Does the glow plug relay send and juice through for the ignition system? The WTS light quit coming on at the same time the truck died.
When the key is "on", shouldn't I get 12 volts at the terminal end with the red/green stripe wire at the injection pump? I'm not getting any.
Does the glow plug relay send and juice through for the ignition system? The WTS light quit coming on at the same time the truck died.