Fuel gauge, temp gauge, tach, signals, not working. SOLVED: Short in reverse switch.

Does your Mitsubishi L300 make a strange noise? Need wheel alignment specs?
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after oil
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Fuel gauge, temp gauge, tach, signals, not working

Post by after oil »

Ok. SO: The fuse was busted. Which makes me seem like a total idiot. BUT: The new fuse busted right away. I'm sure I swapped the fuse first. But it burned out so quickly, that I didn't even have a chance to know that it was that. Now I have another mystery to solve. Why is the fuse burning out? Gonna check the signal lamps.
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Fuel gauge, temp gauge, tach, signals, not working

Post by Growlerbearnz »

the 15A fuse in the dashboard fuse box? As well as the dashboard warning lights and gauges, that fuse also runs the reverse light switch (or A/T shift position lights on an automatic) and hazard light switch.

I'd check the hazard switch first as it's easy to get to. Look for any signs of overheating.

Then check for damage to the wiring harness around the gearbox, past the fuel tank, through the battery box, and along the rear firewall above the engine, especially where it passes through or near metal.
Nothing says "poor workmanship" more than wrinkles in the duct tape.
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Fuel gauge, temp gauge, tach, signals, not working

Post by lrp374 »

Which fuse blew or more than one?
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after oil
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Fuel gauge, temp gauge, tach, signals, not working

Post by after oil »

Dashboard lights and hazards never quit working.
The 15a fuse for turn signals burned. I replaced it but it burned again. I hadn't realized that it burned again but I did check again just looking without taking it out. You could barely see the break.
Front signal bulbs were corroded so I cleaned them

I put a 25a in for now and it seems to be holding. I'm thinking next to check resistance to ground at every terminal on the combination switch plug
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lrp374
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Fuel gauge, temp gauge, tach, signals, not working

Post by lrp374 »

I think Growler is right about the wire grounding somewhere. The interesting thing is the signal and hazard bulb is the same and much of the wiring is the same. Almost leads back to the turn signal switch area. Maybe the larger fuse will let some smoke out so you can find the problem.
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Fuel gauge, temp gauge, tach, signals, not working

Post by Growlerbearnz »

after oil wrote:Dashboard lights and hazards never quit working.
Hazard lights get their power from fuse #2 (10A) not the turn signal fuse #15 (15A) so they would continue to work even if the indicators/dash warning lights/reverse lamps/PRNDL/overdrive switch failed.

(In my earlier post I said "dashboard lights" but meant "dashboard warning lights" (as opposed to "dashboard illumination"), sorry.)

I don't think it's your combo switch. The only connection to this circuit is at the turn signal switch, and it draws its power through the indicator flasher unit. I believe s short at the turn signal switch would make your flasher unit click or buzz, but wouldn't blow the fuse. I'm not confident enough in my theory to test it on my own van though. ;-)
L300FuseBox2.jpg
L300FuseBox2.jpg (34.77 KiB) Viewed 7553 times
Nothing says "poor workmanship" more than wrinkles in the duct tape.
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after oil
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Fuel gauge, temp gauge, tach, signals, not working

Post by after oil »

I'm sort of of the mind that since it's working with a 25a fuse to just leave it alone. I've already spent a lot of time on this and might move on. Unless y'all are really itching for resolution?
Thanks for all the help. All the folks in this thread are delica.ca vets. I was very active in here in the early days but Facebook seems to have broadened my social network horizons from just other delica nerds.
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after oil
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Fuel gauge, temp gauge, tach, signals, not working

Post by after oil »

Update: fuse blows when I put the manual transmission in reverse.
Blows with lamps unplugged. Lamps are LED by the way
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Fuel gauge, temp gauge, tach, signals, not working

Post by Growlerbearnz »

First test is to eliminate the reverse switch. Unplug the the switch, and test for continuity between the switch's terminals and earth, in both neutral and reverse. The switch's terminals should never have continuity to earth, but should have continuity to each other when reverse is selected.

Assuming you've determined that the switch is ok:
Power feed *to* the reverse switch is usually red/green stripe (using standard colours here, YMMV as Mitsubishi has been known to change wire colours on a whim). We know it's fine, since the fuse doesn't blow until reverse is selected.

Which means the other, switched, red/blue stripe wire must be shorting to earth somewhere between the switch and the tail lamps, blowing the fuse when reverse is selected.

With the reverse switch still unplugged and reverse bulbs removed, I would check for continuity between the red/blue stripe wire (harness side) and earth. If it has continuity, unplug the rear lamp clusters (if you're lucky it's just a short in one of the lamp holders). If it still has continuity, start tracing that wire back until you find the short.

That wire runs from the gearbox, forwards along the chassis, under the battery tray near the filler neck, up past the battery, over the top of the engine (this is where it usually rubs through), down into the air filter area, into the right B-pillar, up the B-pillar, backwards along the right top cant rail, then it forks to go;
-down the right D-pillar to the right tail lamp
-Across the rear cant rail to go down the left D-pillar to the left tail lamp.

You could just unplug the reverse switch, I guess, but chances are that if this one wire is shorting out, others aren't far off. Ignoring it is tempting Murphy's Law.
Nothing says "poor workmanship" more than wrinkles in the duct tape.
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after oil
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Fuel gauge, temp gauge, tach, signals, not working

Post by after oil »

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after oil
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Fuel gauge, temp gauge, tach, signals, not working

Post by after oil »

Where is the reverse switch? Is it in the photo in the link above?
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Fuel gauge, temp gauge, tach, signals, not working

Post by Growlerbearnz »

after oil wrote:]What is this in the image?
https://www.dropbox.com/s/sl4dpd1zdxjtp ... .jpeg?dl=0
That's one of the 4WD indicator switches.

Reverse switch is on the right side of the gearbox, just behind the oil pan. Here's a photo of my gearbox just after I removed it, taken from above, with the reverse switch circled:
switch.JPG
switch.JPG (63.84 KiB) Viewed 7506 times
(I'd take a better photo now the gearbox is installed, but it's dark outside now).

The switch has long wires coming out of it, the wires run over the gearbox and plug into the main loom at a couple of bullet terminals on the left side of the gearbox. Try not to disturb the wires where they actually go into the switch, the insulation is usually brittle and will crack.
Nothing says "poor workmanship" more than wrinkles in the duct tape.
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after oil
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Fuel gauge, temp gauge, tach, signals, not working

Post by after oil »

Fantastic. Thanks. Will report back
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after oil
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Fuel gauge, temp gauge, tach, signals, not working

Post by after oil »

If I'm using the multimeter right there's no continuity between the contacts on the switch. I guess that means the switch is faulty. Gonna get out and try to clean it up
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after oil
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Fuel gauge, temp gauge, tach, signals, not working

Post by after oil »

Tested continuity between red and blue wire and ground and there's no continuity. If I'm using a multimeter right. It's set on a little symbol that looks like a Wi-Fi symbol. The terminals are in the appropriate holes. Not getting any beeps.
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