Electical Issues (Overloading Electrics Circuit?)

mcmastai · Post by **mcmastai** » Tue Mar 21, 2017 12:00 pm

So after much research, I have come to a conclusion that my issue has not been addressed!

Basically, I'm having issues with my 91 L300's electrical system. I find if I have too many things running at once, I lose all electrics inside and out (headlights, taillights, fogs, dash lights, clock, radio, etc.), everything but the gear indicator light. This happens if I run my fogs, radio, and lowbeams at once, or fogs and highbeams. I'm sure it might happen with highs and radio as well, although I've been apprehensive to test the theory. When the electrics go out it reminds me of a circuit breaker blowing. I just stop and turn the headlights to "off", and with the truck still running, everything eventually comes back, starting with the clock.

Has anyone experienced a similar issue, or have any idea where to start troubleshooting?

Clark

Post by **Growlerbearnz** » Tue Mar 21, 2017 1:42 pm

The things that go out at the same time only have one common point, and that's in the battery compartment.

I'd start with the battery terminals, and then all the large fuses and fusible links in the battery compartment. Unplug/unbolt each one and check for corroded connections and evidence of heat (melted plastics, blackened wires). Also check the big earth lead- unbolt it and clean it up.

I recall you had trouble starting in the cold recently, I presume you've had the battery tested/confirmed it's in good condition/replaced the battery?

Post by **FalcoColumbarius** » Tue Mar 21, 2017 2:00 pm

Also, possibly the alternator belts? Could they be slipping and not delivering a full charge to the battery(ies)?

Falco.

mcmastai · Post by **mcmastai** » Wed Mar 22, 2017 1:17 am

Growlerbearnz wrote:
I recall you had trouble starting in the cold recently, I presume you've had the battery tested/confirmed it's in good condition/replaced the battery?

Thanks Growler! I'll try those first. The batteries are apparently in good condition, but I'm not sure how much faith I have in them, with the starting issues and all.

FalcoColumbarius wrote:Also, possibly the alternator belts? Could they be slipping and not delivering a full charge to the battery(ies)?

Falco.

I have noticed some slight squealing on some of the colder starts... if the batteries aren't getting charged fully/not pushing enough power could this cause the electrics to cut out?

Thanks guys!

Clark

tomaboyd · Post by **tomaboyd** » Wed Mar 22, 2017 1:06 pm

I would say yes.

Diesels are very simple. Most, if not all, the wiring etc is to get it started and to run all the lights etc. Unlike a gas motor, a diesel does not need electricity to keep running.

You may be getting enough of a charge to get it going again, but not keep the electronics going full time after that. If your batteries fall below a certain level you will loose electonic functionality, but the engine will run until it is out of gas.

mcmastai · Post by **mcmastai** » Thu Mar 23, 2017 11:21 pm

UPDATE:

I checked out my battery compartment today. I didn't have time to load test them, but with the engine running I'm getting 14.17V, so I'm assuming the alternator is good still.

HOWEVER, I decided to investigate the main four plug fusible link coming off the batteries, and for the first time I noticed something amiss.
There are only three wires coming into the front of the fusible link, with the fourth wire removed going straight to the battery through a box. I believe the fourth wire was white/red.

Photo:
https://drive.google.com/file/d/0B3lc96 ... sp=sharing

To me, this looks like someone has (possibly?) burnt one of the links, and instead of replacing it, wired it through an auto-resetting circuit breaker, such as the ones on here: http://www.littelfuse.com/industries/au ... akers.aspx

Anyone have any thoughts?

Right now, I'm thinking I'll just chop it and replace it with a burly inline fuse. If I go this way, what amperage do you guys reckon I should use?

Thanks

Clark

Post by **Growlerbearnz** » Fri Mar 24, 2017 3:29 am

Yup, that's an auto-resetting fuse. Someone has blown the fusible link and, not understanding what its function was, replaced it with that thing.

The thing about fuses is that if there's a serious short through a heavy wire, exposing the fuse to many times its intended current, the fuse will blow in a way that splatters its wire around the inside of whatever's containing it (glass, ceramic, or plastic). The spatter can be close enough that a high-current arc can still jump it.

A fusible link will melt rather than explode, dropping away from the wires at each end, ending a serious short circuit. It's not really a fuse, it's more to stop your wiring catching on fire if something goes horribly wrong.

I'd be replacing the fusible link with another one. The original was a 0.5 square mm, about 20 gauge. https://www.amazon.com/Pico-5557PT-Univ ... B00030CZV4, though you'd have to crimp new terminals to it.

Calculating the fuse that will replace a fusible link is tricky. You want something big enough that the occasional inrush current won't blow it, but small enough that a major short will. The original 0.5 square mm fusible link will melt at 100A, and was rated to carry about 35A continuously, but I'd err on the side of caution and fit a 40A fuse in an emergency until I could fit a fusible link.

mcmastai · Post by **mcmastai** » Fri Mar 24, 2017 9:37 am

Ah, I thought so!

I'm a little confused about replacing the fusible link. Does it matter that the replacement is 8in long? Would I be trimming it to fit? Are they an order-only item?

Clark

Post by **Growlerbearnz** » Fri Mar 24, 2017 2:10 pm

Definitely trim it to the original length (more or less, a centimetre or two either side won't hurt) - use one of the remaining blue fusible links as a template.

I would go the local pick-a-part junkyard and sift through the '90s Mitsubishis until I found a fusible link that matches- but we have a LOT of old Mitsubishis here. Online wisdom suggests that "auto electricians" and "local parts stores" stock the fusible link wire, but I've never looked so I don't know.

dbe · Post by **dbe** » Wed Jun 21, 2017 10:59 am

Greetings!
I'm wondering how you've made out with this issue.
I have a similar issue.. I have no power (electrical) in my L300.
The battery has a solid charge, the terminals are clean and the main fuse off the positive terminal looks good, but nothing electrical works, including the horn or 4way flasher/hazard lights.
I'm about to get my meter out and start checking things, but I'm new to the Delica, so any input as to where to start would be greatly appreciated.

Thanks in advance!

Post by **Growlerbearnz** » Wed Jun 21, 2017 2:52 pm

I would think that if *nothing* electrical works, it's either the positive battery terminal or the earth lead. It would be very unusual (and exciting!) for all the fusible links to fail at the same time.

Get the meter out. Start at the battery and work backwards.

mcmastai · Post by **mcmastai** » Tue Jul 25, 2017 10:27 am

Hi there dbe!

I've left my project for a couple months due to some more pressing matters... I am heading to the electric store today and will be picking up fusible link wire.

Does your bus run and everything still, just with no electrics? What about the light behind the gear indicator on the dash? I reckon it's probably either a ground or split wire somewhere. Did you get it worked out?

Clark