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

after oil · Post by **after oil** » Sun Feb 11, 2018 10:56 pm

Hey folks,
1992 L300 manual. Suddenly Fuel gauge, temp gauge, tach, signals, not working. Dash lights work, headlights work. I was having some kind of grounding or shorting issue: the negative battery terminal would spark and even flame at startup. (I've got a WVO system with lots of electrical parts.) I cleaned that up, it's not sparking now.
I searched the forum and read some threads about gauges pointing to contacts behind the instrument cluster, and issues with the combination (headlight) switch. Nothing though about gauges AND signals not working.
Any insight to this would be greatly appreciated. Thanks!
Ari

lrp374 · Post by **lrp374** » Mon Feb 12, 2018 4:57 pm

I don't have any answers Ari but I have a few questions which may help find answers.

1. Do the signal lights work on the outside even though they don't show inside?

2. Does the front blower fan work?

3. Did all this happen @ once?

It appears you may have burnt off a common ground wire.

after oil · Post by **after oil** » Mon Feb 12, 2018 5:27 pm

lrp374 wrote:I don't have any answers Ari but I have a few questions which may help find answers.

1. Do the signal lights work on the outside even though they don't show inside?

They do not work outside

2. Does the front blower fan work?

Yes it does

3. Did all this happen @ once?

Yes

It appears you may have burnt off a common ground wire.

I've been looking all over for which common ground wire I might have burned. Is it maybe in the combination switch?

lrp374 · Post by **lrp374** » Tue Feb 13, 2018 10:01 am

I think you likely have more than 1 problem. The large wiring schematic from the L300 section makes it look like the blower and instrument cluster use a common ground. If the drawing is correct and the blower works it would seem like the ground connection @ the instrument cluster may be a problem. If the signal lights don't work on the outside it would appear to be a power problem as the 2 systems don't appear to have a common ground . I know the drawing I'm looking @ is not for our vans but I think this part of the drawing is pretty accurate. I'll try to check other common items which might help. Good luck this could be a real head scratcher.

4.I presume all the fuses and fusible links are good.

5. Is you head light control original or are they controlled through relays?

after oil · Post by **after oil** » Tue Feb 13, 2018 10:50 am

Ground for hazards and turn signal is the same, hazards work. i guess this points to switch. as far as i know my headlight switch and assemblies are stock. There are headlight relays under the dash all the way on the right, stock.
I tested the fusible links and they seem good. Theyve got power going through them.

after oil · Post by **after oil** » Tue Feb 13, 2018 10:58 am

I suppose next thing to do is get a headlight combination switch and try that?

lrp374 · Post by **lrp374** » Tue Feb 13, 2018 11:35 am

Have you tried changing the flasher for the signal lights?

after oil · Post by **after oil** » Tue Feb 13, 2018 2:16 pm

Um... No. I guess that's next?

after oil · Post by **after oil** » Tue Feb 13, 2018 4:00 pm

I swapped the flasher relay with one from a parts van. No change. As I understand it, the hazard flasher and the turn signal flasher is the same thing. Hazards work.

I took of the steering column shroud and sprayed WD-40 in the combination switch and tapped on it a bunch, no change.

lrp374 · Post by **lrp374** » Tue Feb 13, 2018 8:35 pm

I had another thought Ari about the fusible links. I had a situation a couple of years ago with my A/C where I went to Vernon with it on, stopped for about an hour and when I came out it wouldn't work. It was getting close to fall so I left it till spring to fix. I did all kinds of things, checked and changed relays measured voltage etc. and all seemed good. I finally found the problem by measuring voltage on the one of the A/C relays. I had 12 V on the relay when the relay was not operating and nothing when it should operate. It turned out the fusible link would provide voltage with no current. As soon as current was required it became an open circuit. I jumpered across the link and all worked fine. At that point I said my goodness why didn't I think of that sooner. I'm not sure that your problem could limited to a single link. With the sparks and smoke maybe it affected one or more of them.

I'll keep trying to come up with more tests.

Good luck be patient!!

after oil · Post by **after oil** » Tue Feb 13, 2018 9:34 pm

Thanks so much for the attention and detailed help! I guess I should remove each fusible link and put a wire between them to test then, eh?

lrp374 · Post by **lrp374** » Wed Feb 14, 2018 5:18 pm

Maybe an easier way would be to pull all the fuses and with the key on check voltage to ground with a 12v light bulb. If some don't have power it should help isolate the power issue. That drawing gets really hard to follow after a while.

after oil · Post by **after oil** » Wed Feb 14, 2018 5:42 pm

Ok. Got it. Also got a instrument cluster, combination switch, and all the fusible link stuff off a parts van.

lrp374 · Post by **lrp374** » Wed Feb 14, 2018 7:38 pm

Must be nice to have a spare!

after oil · Post by **after oil** » Thu Feb 15, 2018 12:28 pm

Swapped all the parts one at a time. No change