1994 Volvo 940 gauge cluster let the smoke out

1994 Volvo 940 Turbo, ~240k miles

I ran an errand to the pharmacy on Friday night and all was well, cluster lights worked, fuel gauge showed half a tank like it was supposed to. Yesterday I went to drive and it showed empty with the reserve light on with key on power. When I started it smoke came out of the dash.



The upper trace is the one that burned first. You can see where I jumpered across the break (long story but I thought I had damaged that section of trace before which is why it burned up). Of course it immediately burnt farther back which you can see towards the bottom.

I believe this is a ground path for a bunch of things in the cluster, including the fuel gauge. Any insights? No fuses are popped and I see no damage to wiring or connectors anywhere. When I got this car two years ago I did have to reflow the solder joints on the back to bring back the fuel gauge so I'm wondering if that's related.

Anyway just curious if anyone has seen anything like this before.

The jumper you made is probably fine but you need to make a cut on the tracer leading to the circle.
The solder at the bottom of the pic (above markings 19 and especially 20) also looks dangerously close to the tracers right above.
I have a '91 Turbo Wagon cluster if interested.

I think I might have to take you up on that. Do you remember the mileage shown on it?

180'ish K.
Before pulling the parts gun out make the cut to isolate the spot where the short happened. It will probably fix your issue. It's a good quality looking jumper that you made but it's not a bypass until the other circuit is isolated. Just take 1/16th out of the path leading to the circle (in the spot just above where the adhesive on the heat shrink you used is showing) and very likely you are gonna be fine.

So an update: I used an x-acto knife to cut out anything remotely scorched looking and cleaned up the solder points again. I pulled more of the harness out so I could look at the back of the cluster when I turned to key on power and it's just created a new hotspot farther down the line on that circuit. I'm clearly not seeing something here.

Just use a meter to see if there is a short on the cluster with the wire harness disconnected. Are you sure the lug you installed is not making the short? Because it looks like it's laying right over the tracer next to it.

Wanted to post an update because I hate when threads die with no answer; I started a new job and didn’t have any time to mess with the car until today. I’m not positive but it seems like the board was shorted somewhere around the light to indicate that the high beams are on. Really strange failure!