Blown PDC fuse
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Blown PDC fuse
Greetings, a Newby here, looking for some help.
I have a 94 F350 Turbo Diesel that just dies intermittenly when going down the road. One of the 30Amp fuses in the Power Distribution Control box under the hood is blown. I get no "WAIT TO START" light on the dash ( controlls Glow plugs) and the truck just turns over repeatedly. I replace the fuse and I can then start the truck. I have ordered schmatics on the electrical system but haven't received them yet. Has anyone seen this before?
History: The truck was hit four years ago and the cab was replaced. The wiring harness is the original. This started once just 9 months ago but has not reared it's ugly head until last week. Now twice this past week it happen. The truck is only used on weekends.
Thanks
RPM
I have a 94 F350 Turbo Diesel that just dies intermittenly when going down the road. One of the 30Amp fuses in the Power Distribution Control box under the hood is blown. I get no "WAIT TO START" light on the dash ( controlls Glow plugs) and the truck just turns over repeatedly. I replace the fuse and I can then start the truck. I have ordered schmatics on the electrical system but haven't received them yet. Has anyone seen this before?
History: The truck was hit four years ago and the cab was replaced. The wiring harness is the original. This started once just 9 months ago but has not reared it's ugly head until last week. Now twice this past week it happen. The truck is only used on weekends.
Thanks
RPM
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From: Virginia
I would look the wiring in the engine compartment over very carefully. Some of the glow plug wiring may be laying on a hot manifold or something like an exhaust pipe. The factory has a lot of little doo-dads to hold the wiring and keep it from rubbing on the engine when it vibrates. Sometimes these harness helpers are forgotten about when the truck has an engine or some other major piece replaced.
Fleet Mechanic
Joined: Aug 2002
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From: Swansea SC
eletrical woes
Rpm , a good book for wiring would be the haynes man.They might make one for diesels but i know the cat#36058 is 1980-1996 f-100thruf350 gas engines but as i recall it s not for diesel application as it says on the front cover . Haynes may have a man for you .This book i use for all eletrcal trouble shooting Good luck TR 
Fleet Mechanic
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From: Swansea SC
haynes
My haynes book doesnt include diesels (even though in the eletrical schematics it is included . Try calling auto zone, advance auto or some other auto center for help . When blowing fuses its usually a direct short . Pain i know, had it happen before. Heat and conditions corrode wires -rubbing hot wires and dirt, dust, pinched wires can be a headache. Print are a must Good luck TR 
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From: Virginia
Fleet Owner
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From: Easton,Ks
Originally Posted by RPM_Diesel
I have a 94 F350 Turbo Diesel that just dies intermittenly when going down the road. One of the 30Amp fuses in the Power Distribution Control box under the hood is blown. I get no "WAIT TO START" light on the dash ( controlls Glow plugs) and the truck just turns over repeatedly. I replace the fuse and I can then start the truck. I have ordered schmatics on the electrical system but haven't received them yet. Has anyone seen this before?
RPM
RPM
2. The Power for the Glow Plug Relay coil comes from a 30 Amp Fuse, Fuse "U" in the Engine Compartment Fuse Box. This Relay Coil is sunk to ground by the PCM like a fuel pump relay is on a gas job.
NOTE: This power from Fuse "U" is shared with the FUEL LINE HEATER and the PCM Power Relay Coil.
I think more than likely you have a bad FUEL LINE HEATER.
Also the "WAIT TO START" indicator is just a lamp turned on and off by the PCM and is powered by a 10 Amp Fuse 17 in the fuse panel under the dash.
My vote is BAD FUEL LINE HEATER.
Info.
A Fuel Line Heater heats fuel to melt wax that might clog the filter and has an internal thermostat to control its operation. This is why it intermittenly blowns the fuse, it depends on the outside air temperature.
Last edited by subford; Oct 31, 2005 at 09:35 AM.
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Cash cow
Man thats great, really appreciate the time to explain it, point out the possible culprits and supply the diagram to boot!! I'll giver a once over this weekend and let you guys know.
Once again...TX!
RPM
Once again...TX!
RPM
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Progress
I took a look at the entire wiring harness for the Blown fuse problem and wasn't able to find a single break short or rube. I disconnected all plugs and reseated them. I then started the truck and haven't blown the 30 amp fuse yet.
Time will tell though. Unfortunately the truck now sputters and shuts off going down the road. It appears to be a fuel problem but I'm not sure how to diagnose. If I pull the fuel line of the Mechanical Fuel pump and it pumps it's good, right? I don't understand how the ejectors are fed, or if the Fuel filter body is full does that mean my mechanical fuel pump is working?
I love diesels but I'm out of my element here
TX in advance for the help
RPM
Time will tell though. Unfortunately the truck now sputters and shuts off going down the road. It appears to be a fuel problem but I'm not sure how to diagnose. If I pull the fuel line of the Mechanical Fuel pump and it pumps it's good, right? I don't understand how the ejectors are fed, or if the Fuel filter body is full does that mean my mechanical fuel pump is working?
I love diesels but I'm out of my element here
TX in advance for the help
RPM
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From: Easton,Ks
Fuel Heater
Removal and Installation
1. Drain fuel filter housing.
2. Remove fuel filter cap and element.
3. Disconnect heating element electrical connector.
4. Unscrew stand pipe from fuel filter housing.
5. Remove fuel heater element.
NOTE:
Bevel-cut gasket must be oriented properly or assembly will leak.
For installation, follow removal procedures in reverse order.
Here is a diagram of where the heater is.
Removal and Installation
1. Drain fuel filter housing.
2. Remove fuel filter cap and element.
3. Disconnect heating element electrical connector.
4. Unscrew stand pipe from fuel filter housing.
5. Remove fuel heater element.
NOTE:
Bevel-cut gasket must be oriented properly or assembly will leak.
For installation, follow removal procedures in reverse order.
Here is a diagram of where the heater is.
Fleet Owner
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From: Easton,Ks
Fuel Filter/Fuel Heater/Water Separator -- Draining
Drain
1. NOTE: To avoid engine stall-out caused by air entering the fuel system, do not drain fuel/water separator while the engine is running.
Stop the vehicle and shut off the engine.
2. Place an appropriate container under the fuel filter/fuel heater/water separator drain tube to collect the drained fluid. The drain tube is attached to the manual drain valve at the base of the water separator drain bowl.
3. WARNING: AFTER DRAINING WATER SEPARATOR, MAKE SURE THAT THE DRAIN VALVE IS FULLY CLOSED AND SECURE.
NOTE: Allow drain valve to remain open approximately 15 seconds or until clear (water-free) diesel fuel flows from the drain tube.
Manually open the drain valve by rotating it away from the fuel filter (9155).
4. WARNING: AFTER DRAINING WATER SEPARATOR, MAKE SURE THAT THE DRAIN VALVE IS FULLY CLOSED AND SECURE.
Close the drain tube by rotating manual valve back toward the fuel filter.
5. Restart the engine and check WATER IN FUEL lamp. The lamp should not glow. If it continues to glow have the fuel system checked and repaired.
Drain
1. NOTE: To avoid engine stall-out caused by air entering the fuel system, do not drain fuel/water separator while the engine is running.
Stop the vehicle and shut off the engine.
2. Place an appropriate container under the fuel filter/fuel heater/water separator drain tube to collect the drained fluid. The drain tube is attached to the manual drain valve at the base of the water separator drain bowl.
3. WARNING: AFTER DRAINING WATER SEPARATOR, MAKE SURE THAT THE DRAIN VALVE IS FULLY CLOSED AND SECURE.
NOTE: Allow drain valve to remain open approximately 15 seconds or until clear (water-free) diesel fuel flows from the drain tube.
Manually open the drain valve by rotating it away from the fuel filter (9155).
4. WARNING: AFTER DRAINING WATER SEPARATOR, MAKE SURE THAT THE DRAIN VALVE IS FULLY CLOSED AND SECURE.
Close the drain tube by rotating manual valve back toward the fuel filter.
5. Restart the engine and check WATER IN FUEL lamp. The lamp should not glow. If it continues to glow have the fuel system checked and repaired.
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I found a broken wire in the base of the fuel bowl, the heater was replaced and It seemed fine. I had it sputter today and it stalled after 10 miles. I then restarted it, and it was fine. I had 3/4 of the fuel housing filled when I poped the cover, is this normal or should it be filled? Also, someone metioned the CAM sensor, how can I check this with an ohm meter?
Apprecaite it!!
Apprecaite it!!
Fleet Owner
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From: Easton,Ks
If it is sputtering when it dies, and then it restart immediately after it dies is what a cam position sensor (CPS) does. The cam position sensor and is notorious for going out on the 94.5-03 7.3L trucks. If you crank the engine and it doesn't fire and the tach doesn't move that’s usually a dead give away. To my knowledge there is no real way to test them aside from replacing it. When it goes out it may do it intermittently or will just stop, but if its not working the truck won't run. They run $100 or less from Navistar and $160-200 from Ford (same part different boxes). Also keep a ratchet and 10mm socket handy to change the CPS out (use a deepwell 10mm socket with a short extension and a 3/8" ratchet). You might want to carry a spare one with you in the glove box along with the above tools, a lot of people do. They're funny, some last 100k, others don't even make it to 20k.
Here is a diagram of its location, it is #8.
Here is a diagram of its location, it is #8.
Last edited by subford; Nov 12, 2005 at 07:06 PM.
