M1028 electrical issues

[bellefourche]

I have been searching around on this forum for a better understanding of my trucks problem, but I am still a little unclear. First, I have a 1028 with the gp resistor bypassed and a manual gp switch, both done by previous owner. When I bought it the starter was grinding on the flywheel because of a broken starter bolt. After that was fixed, the temperature dropped and it wont start when under 40 degrees. One battery is too light for the truck at 700 cca, but with a 60 amp charger connected it still won't go. So I tested the plugs (ac13g), all read between 2-3 ohms. So I tested the manual switch; it's good too. I checked fuses, and replaced a 20a. Turned the key and had all the dash lights come on for the first time. First time I saw the wait, water in fuel, and gen 2 lights. I thought I found the problem so I pushed the gp switch and everything went dark. No dash lights, no headlights, no starter. Smelled a burnt wire, probably a fusible link because all the fuses were still good. I have 26 volts from batteries and 13 at the 12v bus.
1. Is there a link that controls everything from starter to headlights? If so where is it? I looked around the steering column and couldnt see or smell anything.
2. Could my manual switch have caused all those problems directly or should I look for the real cause?
3. Would any of you recommend going to the gp controller from cucv electric to replace the manual switch?
4. Should the starter bolts be replaced with a higher grade to prevent that problem again?

 

[Warthog]

1 - There are multiple fusible links. The wiring diagrams in the Techincal manuals show them
2 - Sounds like pushing the switch overloaded something. Without knowing how the manual switch was wired we can't help you. A single ground wire switch is all that is needed.
3 - The GP controller does many things. Read the sticky on GP operations.
4 - Factory starter bolts is your best option. They are designed to do the job. You also MUST have the support bracket unless you want to keep breaking bolts or you block.

Tell us which 20a fuse you replaced. Just because it had a 20amp doesn't mean it is correct.
Figure out the which link burnt and fix it
Check your battery cables for burnt posts
If the trucks GP system has the 12v conversion, you may need a new GP relay on the firewall.

 

[bellefourche]

Thanks, I realize there are multiple links, just curious if one in particular should supply everything mentioned. The manual gp switch is wired by taking the light blue going to stock controller to ground. I also understand the gp controller does many things, but I am interested in opinions if it's worth 80 bucks to replace the manual switch. I know some on this forum use the manual switch. Also starter bracket is bolted on and was when the previous owner had the starter break loose. I didn't know if those bolts were a weak point, but I'll leave them for now.
A while ago i found a picture showing correct readings for the gp relay, but have searched with no luck. The top bolt and 3rd from top read 13 with key off. Anybody have a quick answer what the 2nd and 4th should read? It's a newer looking silver relay. I am not near the truck to see which fuse for sure, but it was upper left looking at the panel.
Thanks again

 

[MarcusOReallyus]

Hard to help not knowing how your truck was wired, but I'll offer a guess. Some time in the past, the truck blew the 20 amp fuse which disabled the GP card. (Since the GP light came on after you replaced the fuse, I'm guessing it was fine. Was.)

Not being particularly bright, or perhaps just being lazy, instead of fixing the real problem, the PO wired in the manual switch, Incorrectly. That got him going, and again, being not particularly bright, or perhaps just being lazy, he kept it that way.

Then you come along and fix the blown fuse. Now, the manual switch does some very bad things, since things are now powered that used to be dead.

Time to get the TMs out and figure out how it's supposed to work, and start testing some voltages.

 

[bellefourche]

I think that is totally plausible. Thanks, that's what I'll do

 

[Barrman]

Once you figure out the wiring. You will still have a truck not wanting to start below 40°. I would recommend pulling the 13G glow plugs even though they tested ok and put in 8 new 60G glow plugs. I have some glow plugs that test ok with an ohm meter and never get hot when I test them in a vice. Yes, you can pull your current ones and vice test them as well. Actually, that would be a good idea to give you a working knowledge of how long it takes to get one red hot on your push button switch.

 

[bellefourche]

Good advice on the glow plugs, I understand these 13g plugs must be fairly old. Should I update the manual switch to work correctly or go with a new controller card?

 

[cpf240]

First, test what you have. Figure out what works and what needs to be fixed. The card may be fine, as you saw the wait light come on at least once. The switch can be left in as a backup, if wired as others have mentioned here. Good glow plugs, a working controller card, working temp sensor and the correct isolated ground relay should be all you need.

 

[bellefourche]

Ok thanks for pointing me in the right direction. I'll get to testing

 

[MarcusOReallyus]

First, test what you have. Figure out what works and what needs to be fixed. The card may be fine, as you saw the wait light come on at least once.

My fear is that an incorrectly wired backup switch has now fried the controller card, along with other things.




Well, that's what testing is for!

 

[bellefourche]

Just wanted to confirm that MarcusOReallyus' guess was right on. The fuse being replaced fried a fusible link. With both replaced and the manual switch cut out the truck works great. I couldn't tell from the manual that one link powered all the dash systems. I have all working lights and glow plug systems. Thanks for the advice everyone

 

[MarcusOReallyus]

Glad the GP card is okay! Win!