'86 digital dash issues and bulb upgrades

[rrubel]

Been quite a while since I've been on here, but I'm back with questions .

First off, my digital dash (86) has gone completely dark, although you can still see the LCDs functioning properly in bright light. Most of my research here seems to point to a grounding problem, possibly under the hood -- although posters talk about near the driver's cylinder head and I can't find any grounds there... just next to the firewall behind the battery. What color wires should I be looking for, and what else might be the problem? Since the whole dash went dark at once, I'm not suspecting the bulbs themselves.

That said, I've pulled the dash to look at cleaning it and checking for bad grounds in the unit itself, and I was reading about replacing the halogen bulbs with LEDs. Anyone have any thoughts on that? Does it make a big difference in how the dash itself looks? I'd expect brighter, but because of the pattern of light that LEDs produce I'd think there might some darker or unevenly-lit areas.

Thanks...

[RICHR]

 

[K & B Special Products]

Cluster

LED's for you cluster will cause it to fail-too low a voltage.

 

[boomdriver]

Been quite a while since I've been on here, but I'm back with questions .

First off, my digital dash (86) has gone completely dark, although you can still see the LCDs functioning properly in bright light. Most of my research here seems to point to a grounding problem, possibly under the hood No. Its in the digital cluster itself.-- although posters talk about near the driver's cylinder head no, below that on the block, bellhousing or in that area over the oil filter. Look for several black wires on a single bolt. and I can't find any grounds there... just next to the firewall behind the battery. What color wires should I be looking for, and what else might be the problem? Since the whole dash went dark at once, I'm not suspecting the bulbs themselves.Inside the cluster is a 12 pin plug-in socket that hangs on the circuit board when its installed. The pin at the end is ground and it will crack away from the soldered connection on the board. Repair that and it will illuminate the display again. Be SURE of which circuit you are working with. These are fragile, rare and costly to replace ($300min) exchange for a rebuildable core.

That said, I've pulled the dash to look at cleaning it and checking for bad grounds in the unit itself, and I was reading about replacing the halogen bulbs with LEDs. Anyone have any thoughts on that? Does it make a big difference in how the dash itself looks? I'd expect brighter, but because of the pattern of light that LEDs produce I'd think there might some darker or unevenly-lit areas. The low voltage issue....Not sure. It does not make a lot of sense when the halogen bulbs are on a dimmer that will drop the output to zero...thats low voltage too...

Thanks...

[RICHR]

Hope this helps

 

[surfboard]

When my 85 dash went on the blink I replaced the bulbs.Easy to see if there on with the facia plate off.They are behind the round silver disks but you can see if there on around the edges with the key on. On mine they were on but the polarizing film had aged and then you won't see any of the digits .I bought some polarizing film and disassembled the display ,peeled off the old film on each glass (don't break them) installed the new film and worked like new.

 

[rrubel]

Definitely not the bulbs; they all went out at once while I was driving.

I have the main PCB off and I'm looking for cold joints or obviously fried components. No luck so far; will break out the multimeter and see if I can start tracing connections.

Boomdriver, when you talk about the 12-pin connection, are you referring to the 12 pins in a row that connect the top board (with most of the components) with the bottom board (where the LCDs and bulbs are)? I can see where that'd take some stress if things moved around occasionally.

Oddly, I found what looked like some loose strands of wire (from stranded-core wires probably) floating around inside the display unit. MAYBE one of those shorted something out; I cannot see more than one or two actual WIRES in the whole assembly so it's possible they were dropped in if this was repaired before at some time. I'm pretty sure it's not the original unit.

Thanks.
[RICHR]

 

[rrubel]

Ok, so probably through some combination of persistance and dumb luck, when I reassembled everything and put the dash back in the car, it lit up. So either I hit the right joints or it randomly started working again. We'll see for how long...

Thanks for the comments and suggestions. Next tackle: why the power door locks suddenly stopped working.
[RICHR]