Help with dash lights

[Jim_PA]

Prior to installing a new headlight switch, the only lights that worked were my high beam indicator, and my turn signals/flashers.

After installing the new headlight switch, my interior light started working, and the turn signals still flashed when the headlights were off.

Now when I turn on the headlights, and use the dimmer, the fuel gauge has lights, and the 2 turn signal lights and the high beam indicator light up, and actually get brighter/dimmer when I turn the knob. The speedometer lights don't come on... either that, or they are burned out. When I turn on the turn signal, or hit the high beams, the respective light just flickers out.

If I turn the dimmer all the way down so the dash lights are off (but the headlights are still on... the dimmer and turn signal indicators work normally again.

Any ideas?

[Draggn66]

My first guess would be a bad ground somewhere.

[Jim_PA]

Any ideas where to looK?

[byrd]

I agree with draggn it is most likly a bad ground. There should be a short jumper from the metal case of the dash cluster to the cab, try that first. If that doesn't work there are two screws that help provide the ground for the lights and they are on the PCB in the back, make sure they are tight,clean and making good contact.

[396muncie]

Yep, bad ground. My dad's 70 Chevelle had the exact same symptoms. If you pushed on a certain area of the printed circuit from behind, everything would correct itself. Just like Byrd said, I ran a jumper between the back of the metal dash to the nearby cab. Fixed it up great. Good luck.

[Jim_PA]

Originally Posted by 396muncie

Yep, bad ground. My dad's 70 Chevelle had the exact same symptoms. If you pushed on a certain area of the printed circuit from behind, everything would correct itself. Just like Byrd said, I ran a jumper between the back of the metal dash to the nearby cab. Fixed it up great. Good luck.

Howdy neighbor! -- Nice looking truck you have there --

Thanks for the tips everyone, I'll try this out.

[Jim_PA]

I know it's going on 8 months since I asked, but I got side-tracked Here's where I am....

I pulled the cluster, and installed 4 LED's for the background lighting, and bench tested all the lights. I seem to have good connections all the way around the cluster, and the bulbs all work.

I put the thing back in, and found the ground wire clip was on the painted part of the dash frame. I couldn't find a very good place to clip it on the cluster -- Where is it supposed to go???

I rigged it on the lip of the cluster after sanding the paint of a little, and it's on, but not very good. Got in, lights on, and things lit up.

Here's my current problems:

LED's just kind of flicker and jump up and down in brightness as I adjust the knob, If I am REALLY careful, I can make them get dim with the knob.

High beam indicator works fine, turn signals work good (except the dash lights flicker a little each time they blink) then things go haywire when I try the 4-ways... Everything gets FUBAR.... even after I turn off the 4-ways, all the lights are still working wrong. I have to turn off the headlights, pull the keys out, and walk away for a little bit... then if I go back, things will work pretty good again until I pull the 4-way knob... the cycle repeats.

I'm stumped!!! How do I check for good grounds? I put a new 4ga strap between motor and frame, fixed up the motor to firewall ground, re-did the ground from frame to cab... what more can I do?

I thought about putting the spare black from neg batt cable to firewall, and trying to come up with a way to ground the bed better...

Damn, this is frustrating! What's next? New flashers? new turn signal or 4-way switch? I hate to play the game of throwing parts at something.

[Draggn66]

[kbs71]

First most LED's brightness doesn't adjust from the rheostat on the light switch. Sounds like your other problem is with the emergency flasher switch. When I first got my truck, if you pushed in the flasher it would blow a fuse. When I took it apart some of the contacts had popped out and was shorting out the lights. take your steering wheel off and check on the turn signal/flasher switch. It's probably bad.

[Jim_PA]

Originally Posted by kbs71

First most LED's brightness doesn't adjust from the rheostat on the light switch. Sounds like your other problem is with the emergency flasher switch. When I first got my truck, if you pushed in the flasher it would blow a fuse. When I took it apart some of the contacts had popped out and was shorting out the lights. take your steering wheel off and check on the turn signal/flasher switch. It's probably bad.

I bought the "Refractor 5 LED (Xenon White) Wedge Bulb" from ebay, because I thought I read here that they were supposed to work with the rheostat?

I'll take a look at the switch -- just for giggles, I went out, and messed with it again, and now noticed that when I turn on the high beams, about 50% of the brightness goes away from the left half of the dash

[kbs71]

The Hi/Low switch gives a lot of trouble some time. You might want to replace that also.

[Jim_PA]

Originally Posted by kbs71

The Hi/Low switch gives a lot of trouble some time. You might want to replace that also.

The high beam floor switch as well as the headlight switch are new from NAPA

I checked the connector on the floor dimmer, and cleaned up the mounting screws, so the grounding there should be good too.

[mrein3]

Originally Posted by Jim_PA

The high beam floor switch as well as the headlight switch are new from NAPA

I checked the connector on the floor dimmer, and cleaned up the mounting screws, so the grounding there should be good too.

The dimmer switch on the floor isn't grounded. All that switch does, when the headlights are on, is send 12V to the high beam or 12V to the low beam. You can quickly eliminate that by disconnecting it, and checking for resistance. You should have no resistance between the "in" wire and one of the "out" wires and while you have infinite resistance between the in and the other out. When you click the switch the readings should flip/flop.

Here is what I would do:
Put the LEDs on the shelf for now.
Individually test EACH bulb holder with a 194 bulb installed. Only install working bulbs and holders into your cluster.
Then I would figure out a way to bench test the cluster. With a wiring diagram put 12V on the dash lights wire. You need to complete the circuit by putting the negative side of the 12V source on the ground. I believe one of the screws that serves to connect the printed circuit to the metal back of the cluster would work for negative. If that circuit works you should continue to check the other light tracks in the printed circuit. A wiring diagram will be really helpful for this task. If they all those circuits work you can set the cluster aside and start looking at the wiring in the truck.

I have one of those "jump box" deals that works real good for bench testing 12V components in the basement. They are clean, small and can light your 194 bulbs for a long time.

Finding wiring problems isn't hard. It just takes time. Always bench test what you can. Start on one end or the other. By testing the cluster first you are starting on the back end. You can also start at the headlight switch and test each wire that comes out of there. Just because you put in a new component (dimmer switch or headlight switch), doesn't mean they work. A percentage of all components arrive to you in not working order.

[cdowns]

get rid of the clip on ground put eyelet terminal on drill hole in a flange under dash sand to bare shiney metal use nut and bolt to afix ground wire // thats what id do to start and woulldnt be surprised if that fixed the problem

[Jim_PA]

Originally Posted by cdowns

get rid of the clip on ground put eyelet terminal on drill hole in a flange under dash sand to bare shiney metal use nut and bolt to afix ground wire // thats what id do to start and woulldnt be surprised if that fixed the problem

So, that ground wire goes to a part of the dash, NOT the cluster? Thanks everybody -- I'll do some more today.

[byrd]

Jim,
Have you checked the two grounds on either side of the rad support near each headlight? How about checking the plugs at the headlight switch and hi beam for corrosion and or shorts? I still think you have a bad switch, yes even new ones can be bad, or a loose connection. The turn signal wiring is also a possible culprit, you need to ring or ohm out each wire to ground and see if you can find a short to ground.

[Jim_PA]

Originally Posted by byrd

Jim,
Have you checked the two grounds on either side of the rad support near each headlight? How about checking the plugs at the headlight switch and hi beam for corrosion and or shorts? I still think you have a bad switch, yes even new ones can be bad, or a loose connection. The turn signal wiring is also a possible culprit, you need to ring or ohm out each wire to ground and see if you can find a short to ground.

I think I will go out, and re-check, and install a new ground from batt to the rad support. My whole rad support is kinda rusty at the bottom, maybe it's not getting up through from the frame to the rad support well enough? In the process, I'll go over the headlight grounds again. Maybe put some dielectric grease on the connectors? They looked good when I put in new headlights.

Originally Posted by byrd

you need to ring or ohm out each wire to ground and see if you can find a short to ground.

I have a multi-meter... but I'm not sure how to "ohm out each wire..." Can you give me the idiots guide?? how to set the multi-meter, etc? Thanks

[Jim_PA]

Ok, so I broke the turn signal switch trying to get it out. Looked fine except for where It is now busted in 2 pieces... at any rate, I bought another one. In the meantime, I hooked up the test light to 12volts, and 5 of the wires in the turn signal switch harness show up as a ground source?

Dark green, yellow, purple, pink and light blue??? That doesn't sound right to me... or am I testing it wrong?

So then I hooked up the new turn signal switch. Nothing has changed. Added another ground to the rad support, and re-checked both headlight grounds, inspected headlight, and turn signal connections, and everything looks clean. Added some dielectric grease for good measure.

Truck wiring gremlins 100 points... me - ZERO

[RyanG]

You need to take the meter and set it on ohms.....should look like a horse shoe kinda. Then touch your to leads together. That represents a short. Next touch the black one to a good ground on the truck and touch the red one to a bare spot on the wire. If you don't get a reading then there is no short. If you see a zero or anything else then you have a short. Hope that helps.

[Jim_PA]

Originally Posted by RyanG

You need to take the meter and set it on ohms.....should look like a horse shoe kinda. Then touch your to leads together. That represents a short. Next touch the black one to a good ground on the truck and touch the red one to a bare spot on the wire. If you don't get a reading then there is no short. If you see a zero or anything else then you have a short. Hope that helps.

Ok, thanks, I'll give that a try!

[71tahoe]

It also helps to have the battery positive disconnected so you don't have any voltage through the wire. Newer multimeters should be protected but they don't like voltage when checking ohms.

[Jim_PA]

Originally Posted by RyanG

You need to take the meter and set it on ohms.....should look like a horse shoe kinda. Then touch your to leads together. That represents a short. Next touch the black one to a good ground on the truck and touch the red one to a bare spot on the wire. If you don't get a reading then there is no short. If you see a zero or anything else then you have a short. Hope that helps.

I set it to 2K on the Ohm setting, and the same colored wires: Dark green, yellow, purple, pink and light blue gave me a reading from the turn signal switch connector (with the turn signal switch disconnected) I'm guessing this means I have a lot of wiring problems? The last wire on the connector gave me a reading of -1

Everything works, just the dash lights are hosed... maybe I'll just live with it