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I am seeking possible solutions for my box truck that recently became a "NO CRANK", as scanner Danner calls it.
This truck is:
2003 GMC W4500, W45042, 6.ol V8 efi
It is a gas engine and not a diesel. I do not have any diagnostic codes, sorry. VIN# 4KDC4B1U93J803737
The main problem is there is no 12 volt power at the key switch and I've taken the shroud cover off the steering wheel to confirm that there is no voltage from the incoming wires to power the key switch telling me the key switch is fine and the problem is between the battery and switch.
MORE INFO: The instrument cluster does not light up; the heater fan control seems to be dead too. Other things do work in the cab such as the dome lights. The head lights work fine, emergency lights work but nothing that is turned on by the key switch works.
I've gone through the many relays on top of the dash board and all check out fine on the ohm meter. I've jump wired the relays too to make sure there wasn't any issues with bad relays and it didn't change anything.
I've checked the fuses in the glove compartment, I've also checked the other fuses located behind the glove compartment. All fuses checked out okay.
I don't understand why there is power in the cab but not at the key switch.
I did get the truck to run by putting a jumper between the solenoid and [+] on the battery. But to get the engine to start I also had to provide 12 volts to the back side of the key switch - to make the fuel pump work I believe. To start the engine I touched the jumper to the batteries' positive post and the engine immediately started.
I've searched and searched for more info on this particular truck but there isn't much out there for some reason. Plenty of info on other models, diesels etc but not on my model that has the gas engine.
If I've left some info out, let me know.
Any ideas?
I clamped on to the positive post on the battery with a jump wire and powered the ignition switch that way. The power [was] at the fuse box, but would not make it through to the key switch (which it 2 feet away at the most).
i also put a separate jumper on the solenoid also the the positive post to get the starter to crank.
The engine will crank by just jumping the solenoid, but will not start up. I have to run a separate wire up to the back side of the key switch and turn the key on for the engine to start.
I hope I've answered your question.
More on the problem:
I really believe there is something in the cab that is the cause of the open line between the glove box fuse bar and relay panel that is not allowing the 12 volts to continue on to the key switch. Is there a 3rd fuse link between the glove box fuses and the key switch. I know there is 3 fuses also in the glove compartment but they all check out fine. This is what is got me stumped.
So I keep getting conflicting info on whether or not this truck has a fusible link. Couldn't find one, however one guy said there's a fusible link in the cab. Could this be true?
In all honesty, I would run a new wire and call it fixed.
You can do a nice job and route it where it won't chaff or be ugly and of course add a fuse. It's a perfectly acceptable repair.
I haven't looked at a diagram for that truck, but if you're positive that the power feed for the ignition switch comes from the interior fuse panel, and you have power at that fuse but not coming out of the box, it could be a faulty fuse box.
The pdf John linked shows a fuse/relay box on left side, rear of the cab, and fuse # 2 in it is named "Key". Pages 244 & 246 in the pdf. That's where I'd start looking.
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