stuck - electrical problems

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YukonCruisers

YukonCruisers

10 Year
Joined
Sep 1, 2014
Threads
76
Messages
742
Location
Whitehorse, Yukon
Last night I swapped the positive batt lead, no issues. This morning my kid says fuse box came loose, some sparks, but truck restarted. Now, no power - he has just left to get a new multimeter (mine just died). Looking for ideas as to fault. Lights don't work, newer Batt (and no change w jump), can bridge starter to turn as well.
Think problem is under dash or hood?
 
I would start looking where the sparks came from, an arc leaves a mark. Most likely a fuse blew to clear the fault, find out what caused the sparks and you should be able to find the problem.


BTW, meters don't just die, they either blow an internal fuse or the battery needs replaced.
 
Apparently the sparks came from the back of the fuse box as it rubbed the frame (seems a little unclear). Anyway, I inspected each of the fuses and the harness and there does not seem to be any obvious signs of an arc. At that point my hands got too cold and I gave up for tonight (its a relatively safe school parking lot, so will go back tomorrow).
It does sound like a blown fuse or failed connection because everything is dark - no main lights, no click for the starter etc.

I hate electrical, been my nemesis on both 40s....

(the old meter has been abused, dropped and sworn at at various times - could just be the battery, but the 9volt is half the cost of a new one anyway)
 
As @Living in the Past sajd, you probably blew the fusible link (if you have one) between the battery positive and the passenger side harness.

Bottom-left corner, between the two white connectors.
IMG_4802.webp
 
Ah, I think I have/had one of those (thanks for the pic). Do they burn right through when blown?

I know tonight I noticed a wire dangling there, but I assumed it had been something previously bypassed since the wires looked pretty corroded - but I couldn't find the appropriate other end...

Will look more closely tomorrow.

By the way, the puzzling part for me is that he was able to restart the drive the truck the rest of the way to school after the fuse incident, it only went dead the following time he tried to start it.. perhaps it frayed and only then broke the fuse...

(Danny, I hadn't seen one of those accessory bars for the battery before...slick - beats stacking wires on the pole for sure)
 
The "accessory bar" is actually circuit breakers for a winch.

The fusible link is intended to burn up (like popping a fuse) before your harness burns up.

It could be burnt through, or merely burned internally (inside the insulation).

You can buy a replacement from @Coolerman.

I wouldn't merely replace it with wire, to get it home. If you still have a short, you could melt your harness.

You could pick up a coil of fusible link wire at an auto parts and try bypassing your fusible link, to get home.
 
Before replacing the fusible link, I would use the new voltmeter to check the continuity of the disconnected link (ohms should be zero) and if it's blown, check for voltage between the inlet/outlet of the link circuit (with the link removed, of course). With EVERYTHING turned off in the truck (including accessories) the voltage should be zero, signifying no current draw. If there is draw, your short may still be there.
 
Good idea 73 - will do that for sure.

I am about to head out shortly and will grab some fusiable wire - failing that, because they may not have it, I'll drop in a 60amp fuse until i can find some (have a 40 amp alternator) - here is a cut and paste from dfmorse on the subject of fusible links in case someone finds this thread and needs the info:

From here:
Fusible Link Size

The fuse link is really just a piece of wire that has been factory calibrated so that your ammeter reads sort of correct and to protect some of the external wiring in case of a short circuit [not the starter]. The resistance of this wire is on the order of 1 milliohm. It takes a sustained high current (around 100 amps) to heat this wire to red hot and then burn out, literally. This means that it acts like a very slow blow fuse. When you start the cruiser, the alternator dumps a surge current of around 50 amps into the battery thru the fuse link, but only for a couple of seconds; the current then drops rapidly to around 10 amps.

You can put a fuse in place of the fuse link; however, it is of un-known resistance. A fuse like this:
Blue Sea Systems, MEGA / AMG Fuses

will probably work, but if the current limit of the fuse is approached it may blow when it is not suppose to. A high current fuse with known slow blow characteristics would be what u need to look for. Of course, the ammeter will not read accurately off a fuse system without knowing the meter electronics (internal resistance, etc).
 
Turns out it was the fusible link. I am guessing my son removed the battery end of the wire when he was trying to fix it and it had burned down almost to the plug on the other end so initially i didn't even see there was a connection there (although I did think it odd i had left a short wire not covered off). Anyway, appreciate the help, we are back up and running.
 
YukonCruisers said:
Turns out it was the fusible link. I am guessing my son removed the battery end of the wire when he was trying to fix it and it had burned down almost to the plug on the other end so initially i didn't even see there was a connection there (although I did think it odd i had left a short wire not covered off). Anyway, appreciate the help, we are back up and running.
Click to expand...

Great!!

Hope you replaced it, with a fuse or fusible link!
 
One real good reason for using the fusible link wire, not just regular wire, is that the "plastic" exterior coating is specially formulated to not spread hot "plastic" sparks all over. If the exterior coating gets hot enough to blow along with the interior wire strands sparks will not be splattered all over, much reducing any risk of fire being spread.

Don
 
Thanks guys,
Yes, the local store had fusible link, installed one, and got 2 extra (one for each cruiser).

Don, yeah, I don't know what happened to the original - it appears to have evaporated to the point where I ended up chasing the wrong +ve supply through the dash on Friday before my hands got too cold to work. Although he wont admit it, its also quite possible my son discarded the remnants when he was troubleshooting too. Anyway, another learning care of the 40 :)

Cheers
 
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