Man this Dash is messed up

[Newman82]

headlights turned on:
No dash lights work, except for both turn signals are always on
Fuel gauge drops to empty
1 light on the heater/ac controls shines very dim
Engine temp gauge maxes out

All of my exterior lights work fine
86 c10

 

[Cuba]

I would start by checking your grounds on the foot well near your fuse box (to the left of it) under the steering column. To me, it sounds like there's corrosion preventing a good connection. Cluster receives its ground from there, also may have issues with wipers? Or radio?

 

[chengny]

headlights turned on:
No dash lights work, except for both turn signals are always on
Fuel gauge drops to empty
1 light on the heater/ac controls shines very dim
Engine temp gauge maxes out

All of my exterior lights work fine
86 c10

It is possible to offer more background on this condition?

For example:

Did it develop overnight or gradually?

Have you made any modifications/installations or repairs lately?

What diagnostics have you already done to determine the cause?

Any maintenance/repairs done to remedy the problem?

Is it only when the headlights are illuminated that this happens - or does it also happen when the parking lights are turned on?

Does switching to high beams have any effect?


I'm not trying to be a wise ass, but it is really hard to diagnose electrical issues (esp. over the internet) when given just a list of what doesn't work right. It would be to your benefit to provide as much information as you can.

Alright, I'm done.

First, if it only happens with the H/L's on, check your forward lighting system ground points. There are 3 of them (see below): one on each side of the radiator support and another to RH frame rail . Make sure the bolts are tight and the landing areas for each are clean to bright metal.

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The big question is whether it only occurs with headlight operation or if even just the parking lights are turned on. If it happens only with H/L's it is related the sealed beam circuit. If it happens with both the H/L's and parking lights, there is a problem with the instrumentation lighting circuit. The instrument cluster is illuminated in both of the H/L switch positions, so if it is only happening when the headlights are energized look, at the headlight wiring. If it happens in either H/L or parking mode, it is a instrument panel problem.

Let us know. Check the common dash panel ground lead per Mr. Cuba and clean/tighten the fwd lighting ground connections first. But unfortunately, I have a feeling you're going to have to become familiar with how to pull the instrument cluster.

 

[Newman82]

This happens with the headlights or the park lights on. If i turn the headlight knob to the right the fuel gauge goes to normal along with the temp gauge. If its turned to the left the fuel gauge 0's out and temp gauge maxes out, and the turn signals are both lighted.

I wish i could give you more info and/or possibly rule out different causes. I have very limited knowledge about the electrical. I removed each of the above mentioned grounds and cleaned them. I did not remove the ground next to the fuse box. It looked very clean. I pulled the fuse labeled intrum lights also. It looked fine. The lights barely worked when i first bought the truck and soon after this problem began. The only electrical change i have made was a new radio. But this was after the fact.

 

[Georgeb]

Look at the printed circuit on the back of the cluster. There may be damage to the tracing for the ground on that.

 

[HotRodPC]

I would be checking the ground to your lights, especially the headlights and side marker lights. It could be possible, the grounds are weak or non existent. And just because they LOOK or APPEAR to be there and tight, don't ASSUME anything. Loosen them up, wiggle the eyes around a bit as if to clean metal to metal contact and retighten. What could be happening is, your light grounds are not good and tight, and the those circuits are trying to ground through anything possible.

As weird as it sounds, bad body to chassis, chassis to engine, engine to body etc etc grounds can cause even transmission problems. More common in the E transmissions, but things like lock up converter can goof up if those grounds aren't right. Reason being, electrical items will try to find a ground to the engine or from the engine to chassis ground. This affects the transmission because whatever item looking for a ground can try to get chassis to engine ground from via frame to transmission through the transmission shift linkage the goes from the frame to the transmission, and also from the body to chassis or engine because the transmission linkage is also connected to the streering column. It's rare, but yes, it can happen and that's how very weird things happen.

 

[HotRodPC]

This happens with the headlights or the park lights on. If i turn the headlight knob to the right the fuel gauge goes to normal along with the temp gauge. If its turned to the left the fuel gauge 0's out and temp gauge maxes out, and the turn signals are both lighted.

I wish i could give you more info and/or possibly rule out different causes. I have very limited knowledge about the electrical. I removed each of the above mentioned grounds and cleaned them. I did not remove the ground next to the fuse box. It looked very clean. I pulled the fuse labeled intrum lights also. It looked fine. The lights barely worked when i first bought the truck and soon after this problem began. The only electrical change i have made was a new radio. But this was after the fact.

Have you tried to loosen up the headlight switch itself? Loosen it. Clean the parts that rub against the sheet metal as it tightens back up. I'm pretty certain the headlight switch is self grounding to the dash sheetmetal as it's tightened up. If it's gotten a little rusty between the switch, the dash and mounting tightening ring, maybe the switch ground is weak.

 

[Newman82]

I just ordered a new headlight knob from LMC. I took apart the 3 headlight grounds in the front and scuffed them up and cleaned them. Also made sure they had clean metal to contact with

Tomorrow i am going to take the dash out and see what i can get into? Time to watch more videos and see what i can learn. My turn signals stopped flashing a while back. That would just be the flasher right? Never thought about them being connected. The hazard lights flash, but the turn signals do not

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[HotRodPC]

You're on it. I think you're doing well. Those grounds are checked, the switch on the way... Hopefully that will bring some resolve. Keep us updated after the switch replacement.

 

[Newman82]

Ok so a new headlight switch has been installed. New flasher also. Found a broken ground under the dash that i did not find previously. Turn signals now work! Fuel and temperature gauge work with the headlights on! Somehow i lost power to my dome lamp and cargo lamp which previously worked.

My oil gauge is still pegged and not reading correctly. Where is the sending unit to that? Thank you all for the help! I truly apreciate it. Definitely learned a ton the last few days messing with this

 

[Cuba]

Great job on fixing what you did so far. On your setup though, I think the cargo and courtesy lights get their power through the headlight switch? Doesn't the headlight switch when turned instead of pulled, switch the courtesy light on & also works as a dimmer for the dash? lol Been a while since I've worked on one. And the sender for the oil is on the engine block. Usually pegs to zero when they go bad, but I suppose anything is possible. Could be the wires are touching each other too which would make it peg high.

 

[Honky Kong jr]

My cargo light is on a switch on the "B" pillar if you will. Also my dome light are on a seperate fuse as I have it pulled so I don't drain the battery but my cargo light doesn't work with the fuse pulled. Mine is an 87 but shouldn't be much different. As for the gauge pegging I have my gauge wire attached to low pressure switch more or less to keep the wire where I can find it. With no pressure it is straight to ground and pegs the gauge. I use a mechanical gauge I don't trust the electric ones.

 

[chengny]

This happens with the headlights or the park lights on. If i turn the headlight knob to the right the fuel gauge goes to normal along with the temp gauge. If its turned to the left the fuel gauge 0's out and temp gauge maxes out, and the turn signals are both lighted.

I wish i could give you more info and/or possibly rule out different causes. I have very limited knowledge about the electrical. I removed each of the above mentioned grounds and cleaned them. I did not remove the ground next to the fuse box. It looked very clean. I pulled the fuse labeled intrum lights also. It looked fine. The lights barely worked when i first bought the truck and soon after this problem began. The only electrical change i have made was a new radio. But this was after the fact.

Unfortunately, there is no silver bullet to diagnose this. You will need to inspect the wiring . I am sure that when you find the problem, it will jump right out at you. I realize it's hard to work on a circuit when you are totally unfamiliar with how it is run. Below is an accurate - but simple - dwg of what you are working on:

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[HotRodPC]

Losing power to the dome and cargo switch that worked previously would make me think maybe a defective headlight switch. This is provided you didn't blow a fuse during the switch swap.


Oil gauge pegged is a grounded out wire or sending unit. The Sending unit is back of the block around and under the distributor. Find that wire to the sending unit, and just unplug it making sure it's not laying to ground. If the gauge is still pegged then you know it's NOT the sender, unless you have a multi problem. If it just stays at Zero after unplugging it, then you know the sender has gone to full ground and is defective and needs replaced.

 

[Newman82]

I will check for the sending unit next.
The dome/cargo light where fine until i took off the inside grounds and cleaned them. Then afterwards i noticed they were not working. That was still with the old headlight switch. Thank you all! It looks like i installed a new gauge cluster! I have never seen the whole thing lit up