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Jeremy, Certified Truck/Bus Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 3321
Experience:  ASE Med/HD Truck Technician, NATEF Diesel Engines and Electrical/Electronics Technician, EPA 608/609 HVAC Certified, Steering/Suspension and ABS/Brakes Technician
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Glow plugs not working. Hard starting in cold weather. No

Customer Question

Glow plugs not working. Hard starting in cold weather. No power to glow plug relay. Can get relay to work when a jumper is connected from starter wire to relay signal post. Checked for power at plug going to relay. Checked all fuses but cannot tell if there is a fuse specific to glow plugs because fuse box cover diagram is missing.
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  cumminsdr replied 1 year ago.

What engine do you have?

Customer: replied 1 year ago.
Sorry i probably did not enter in the vehicle info? 98 Mitsubishi fuso. Mitsubishi diesel 4cly.
Expert:  Jeremy replied 1 year ago.

My name is ***** ***** I will assist you.

What model of Fuso do you have? FM? FG? Etc? I'll pull the diagrams off the Fuso site. There is a glow plug fuse, but I'll need model or full VIN to get diagram.

Customer: replied 1 year ago.
Customer: replied 1 year ago.
vin JW6AAE1H0WL00207
Expert:  Jeremy replied 1 year ago.

I apologize for the delay.

There are problems with the Mitsubisho servers. We can sign in and then we get time out errors. Apparently thr issue is the whole network and Mitsubishi is working on it. New year woes I guess.

I am waiting on that network to come up so I can provide you diagrams for the glow plug system to help you locate where the power loss is at.

Expert:  Jeremy replied 1 year ago.

System finally up.

You will want to check fuses 18 and 20 for the glow plug circuit. Here is the diagram. CLICK HERE

As you see in the diagram, the power goes from fuses to the timing control unit and then to the relay. If the fuses are good, then I would check the timing control unit. There is a few checks on it to check for power as well as to see that it is getting an input signal from the engine coolant sensor. CLICK HERE to get an understanding of how it works as well as what to check on it.

Hopefully it is just a fuse problem because the timing control unit can be a pain to work with. If you are getting the signal in, but nothing out, the timing control module is bad and needs to be replaced. There are 3 circuits in. Start, temp, and alternator. If the alternator signal is not coming in, you usually wouldn't even get charging on the truck. Now you can have a bad temp sensor and still get a normal reading on the dash for they are 2 different sensors. One is the sender unit sensor and the other is the coolant temp sensor for the engine. So I would start there first if the fuses are good to keep you from chasing ghosts all over the whole engine.

Again, I apologize for the delay for the site was down and I couldn't pull anything today after I got your VIN info.

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Customer: replied 1 year ago.
No worries on the delay. I am in and out as well so i expect to be playing tag with you anyhow. There is no fuse panel cover so i have no idea what fuse numbers there are. I have checked all the fuses in there and they are good but if i count from left to right there are 17 fuses in a row and there is a fuse missing from where i think 18 might be? Also is there another fuse panel anywhere? The one i am looking at is in the center of the dash.
Expert:  Jeremy replied 1 year ago.

You have the one in the dash and the one at the battery box. The battery box is the large main fuses. The one you need is in the dash.

When looking at the fuse panel in the dash, the bottom left is 1, bottom far right is 17. Top is 18 and far right is 34. CLICK HERE for the fuse panel break down. Since you don;t have the cover, I would keep this in a safe place by downloading to your hard drive and/or printing for the glove box.

Expert:  Jeremy replied 1 year ago.

I see you viewed this and this is still showing as a open question due to no positive (3 stars or more) rating.

Did you still need assistance with this?

Customer: replied 1 year ago.
sorry after viewing it i lost my password ***** since i wrote my email down wrong by one letter it took all day today to get it reset so i could log on again. I need to run down the wiring chart since the fuses all checked out. Please give me some time (a day or so) to see if i still have more questions. Thanks!
Expert:  Jeremy replied 1 year ago.

Let me know if you find anything. The other message above is a uto reply to see if you still needed more help is all.

Customer: replied 1 year ago.
I have not yet ran down the wiring for the timer but seeing as how the timer also does intermittent wiper i tried those. the hi and lo work but the INT setting does nothing. is that an indication that the timer is bad if i can verify it is getting power?
Expert:  Jeremy replied 1 year ago.

You would check the timer itseld to see if you are getting power into it, then you would check to see if you are getting ground, then a signal in. If you are getting all 3, the timer is bad.

There is no other simple way than putting the multimeter right to the pin and checking voltage.

Customer: replied 1 year ago.
Ok where is the timer module located? I apologize if you already told me but i cannot find it.
Expert:  Jeremy replied 1 year ago.

It's been awhile since I worked on a 98. If I recall correctly, it's behind the dash, middle towards the right side.

Customer: replied 1 year ago.
Any idea what size color shape it is? I found a few different sized stand alone relays by the fuse panel but they do not seem to have enough wires. Then on the right side above the hvac unit is another relay panel with 3 different boxes screwed into the board. one is labeld turn signals and the other two are not labeled.
Expert:  Jeremy replied 1 year ago.

It's a large red square ECM looking box with one plug going to it. Black in color. It isn't a relay box with relays like standard relays. It is a relay box that is sealed, a ECM looking module. If it is bad, you have to replace the whole thing.

Customer: replied 1 year ago.
Is there anyway to send you pictures? I have the entire dash apart and see nothing like you describe.

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