Gauge Cluster Lights

[MIDEVIL214]

(74, OEM Harness & Cluster)

Replaced my cluster voltage regulator, temp gauge and fuel gauge today. Got it all back together and my cluster illumination lights aren't working. Hazards, turn signals and high beam indicator bulbs are functioning, just not the three bulbs with blue/red wires. All are securely pressed into the back of the cluster housing.

Don't see any pinched or disconnected wires and the fuses are all good. They all illuminated prior to the cluster repair. I even had a new spare head light switch that I installed with no luck.

It took some wiggling to get the cluster out behind the dash but other than that no issues installing gauges and reinstalling the cluster. I also noticed that the small heater and wiper/headlight dash indicators are not illuminating. Not sure if they were working before though to be honest.

I've triple checked everything except the loose nut behind the wheel...

Thoughts? Been over the Seabiscuit68 diagrams a bunch tonight.

 

[DirtDonk]

It's a pretty basic circuit, so hopefully it'll be a pretty basic fix too. I hate coincidental failures on Broncos though!
Seems like you touch one thing and three others go south just at the same time.%)

Did you check at the small fuse in the panel? The little tiny odd one is for the cluster illumination. Be a good thing to at least remove it and put it back in, just in case it's a slight case of the corrosion blues that's got it down.

And I'm assuming you turned the rheostat all the way one way and the other (up against the "click" for the dome light) to see if anything changed?

It's unfortunately all too common nowadays for the light bars on the dash to have failed. Sometimes just one or two bulbs, sometimes all of them inside. But check them again after you get the cluster lights working again.

Good luck. Hoping it's the fuse.

Paul

 

[MIDEVIL214]

Thanks Paul. Yes, I did mess with the dinner adjustment on the headlight switch. I tried three new fuses with no luck. I put a volt meter on the tabs of that fuse holder and found 12 at the front tab and zero at the back tab. This was with new fuses installed.

 

[Broncobowsher]

Well that is a blown fuse. Sounds like you have a short that took out your new fuse.

I generally unplug as much as possible and try a new fuse again. Did it blow? Yes, you still have a short in something still hooked up. No, the short is unplugged. Start plugging stuff in until the fuse pops again. At some point you will hook something up that blows the fuse and that is where the short is at.

 

[MIDEVIL214]

Well that is a blown fuse. Sounds like you have a short that took out your new fuse.

I generally unplug as much as possible and try a new fuse again. Did it blow? Yes, you still have a short in something still hooked up. No, the short is unplugged. Start plugging stuff in until the fuse pops again. At some point you will hook something up that blows the fuse and that is where the short is at.

I wondered about that but have installed four new fuses now. All appear to have the element intact and not blown. Checked voltage wire going to IVR and its good. Checked voltage at one of the dash bulb sockets and nothing.

 

[66broncoCT]

That's a tiny fuse it could be blowing as soon as you put the new one in and you might not see the element broken. Check the fuses with your meter to see if they're good or not. Or your tabs that hold the fuse could be dirty/corroded and not letting the voltage through.

 

[DirtDonk]

That.
The IVR has no function regarding the dash illumination. The fuse panel itself may be deteriorating to the point you will have to fix it.

Did you access the back of it to see what it's looking like? Some of them are pretty crusty and need some TLC to get back in shape.

Paul

 

[MIDEVIL214]

That's a tiny fuse it could be blowing as soon as you put the new one in and you might not see the element broken. Check the fuses with your meter to see if they're good or not. Or your tabs that hold the fuse could be dirty/corroded and not letting the voltage through.

I just tested and installed new fuse - good prior to going in, turned on lights and attempted to adjust dimmer and nothing. Pulled fuse and it shows nothing on the multimeter.

The back of my fuse block looks good. No corrosion and all wires are intact and tight. Seeing everything was working correctly before cluster removal yesterday, I may have pinched a wire somewhere. On a side note, it looks like my new fuel gauge is not reading...

 

[DirtDonk]

Sounds like you're on to something!

Good luck.

Paul

 

[MIDEVIL214]

Couldn't find any obvious wire issues. The blue/red wire that runs to the gauge lights is sealed up in the factory harness too with no signs of disturbance.

I left all three lights out of the cluster and installed new fuse. Blew it right away after key and lights on. Even tried grounding bulb socket to different ground with no luck.

Sure dont understand how installing new IVR, fuel and temp gauge would cause these issues.

 

[DirtDonk]

Any luck on this yet? Even tried, or moved on out of frustration to come back later?
Well, back to the top for some fresh eyes maybe.

To your last question though, directly none of those three items have anything to do with the illumination circuit. The relationship pretty much stops at the case around the gauges, since that's where the bulbs ground.

A bad ground won't cause a short circuit and a blown fuse. An unrelated circuit won't cause a blown fuse either, unless they're somehow touching.
What about the dash light bars? Can you disconnect them too, just to rule them out?
Hmm, two more items that are related directly are the map light under the dash and the radio.
If yours does not have one of the optional map lights, it still has the wire. Check under there to see if the loose end is somehow touching metal. Unusual to be sure, but not impossible.
And for the radio, do you have a factory radio still?
What about a tachometer, extra gauges, or anything else that might be connected to that light circuit?

Paul

 

[MIDEVIL214]

Emotionally gave up a few times. Tried some things on Sunday but wont be able to get back to it until the weekend. Those fuses are hard to find so testing is limited when they blow immediately. My last attempt was to remove the cluster again and reinstall, just to check things over. This changed nothing

Tach - I do have an aftermarket tach that was tapped into the back of the headlight switch for illumination. Worked for years with no issues this way. I removed the tap and sealed the spliced wire during last test and fuse still went.

Light Bars - will give it a shot. Need to remove CD player to get to one of them

CD Player - Power wire is tapped into tach power wire which is connected to back ignition switch post. Been that way for years too. May have to revisit the OEM radio power wire if it's connected to those dash lights somehow. I didn't hook up the CD player but have had it out before.

Map Light - never had one, have dome light though. I do have a yellow/black wire under dash near the e-brake with no home. I've owned the vehicle for over 20 years and this has never been connected. Insulated the wire connection portion just so it wasn't touching anything.

Have intermittent wiper switch installed but I don't believe that was tapped into circuit in question.

Recently wired in a team tech offroad fuse/relay box under the hood but only tapped acc power at ignition solenoid and +/- at battery. Tested the accessories and switches but never paid attention to dash lights. Nothing wired into the circuit discussed though.

Appreciate the follow-up Paul.

 

[Broncobowsher]

Once you find it, it will be an incredibly simple fix.
I fixed a car once that had an interior light fuse that did the insta-blow, when the spoiler on the trunk was reinstalled the trunk wire got caught under the screw head shorting it to ground. Very simple fix, but finding it was challenging. Especially since it wasn't at any of the end users of the circuit.

 

[Skiddy]

Once you find it, it will be an incredibly simple fix.
I fixed a car once that had an interior light fuse that did the insta-blow, when the spoiler on the trunk was reinstalled the trunk wire got caught under the screw head shorting it to ground. Very simple fix, but finding it was challenging. Especially since it wasn't at any of the end users of the circuit.

I bought a 280Z very cheap once because it wouldn't run that had a similar issue

 

[DirtDonk]

A bunch of older Buick Regals had trouble with their front running lamps that turned out to be the wire harness to the trunk lid!
So check your trunk lid and spoiler!

Paul

 

[MIDEVIL214]

Pulled the CD player to check for a short at heater control illumination wire. Found a self-tapper that mounted an accessory switch bracket below dash protruding into the OE harness. That was the short causing the blown fuse and gauge illumination issue. Wish I could blame the placement of that self-tapper on someone else.

 

[Skiddy]

Pulled the CD player to check for a short at heater control illumination wire. Found a self-tapper that mounted an accessory switch bracket below dash protruding into the OE harness. That was the short causing the blown fuse and gauge illumination issue. Wish I could blame the placement of that self-tapper on someone else.

doh did the same thing once except took out all power and fusible link:-[

 

[Broncobowsher]

Told you it would be something really simple, once you found it.