speedo/temp/tach lights not working

[DotSoon]

couple months ago i was driving at night and the speedo/temp/tach went dark but the clock and the gas gauge are still lit.  i hit a bump and they came back on, but the next time i drove they were out again.

 

i pulled the instrument panel out and switched the bulbs and nothing changed.  everything looked fine on the back.  i cleaned the contacts where the wiring plugs in.  

 

i am at a loss.  going to study the wiring diagram again to see if there was anything i missed. 

 

any insight would be greatly appreciated.

 

thanks

[84720FourWheel]

Sounds like a loose connection somewhere.

[wayno]

Spin the knob for the dash lights a little, maybe it's in a bad spot.

You can see the knob next to the cig lighter knob in the photo below.

[DotSoon]

I've spun the dimmer switch back and forth... ill just take everything out again and check.  wiggle everything a bit to see if there is a short or loose connection.

 

thanks for the input. :)

[wayno]

Have you pulled apart the combination switch and cleaned the headlight contacts, cycle the headlight knob a few times, wiggle the arm, see if that helps.

[harlow426@msn.com]

flushing out the multi switch with light oil will help regardless. take off plastic steering column 'cozy'....drip pan on floor. flood headlight twisty.....turn sig pivots contact etc. blow off exxcess w/ comp air. paper towels daub up remaining.

 

wouldnt hurt to lube steering lock mech while ur @ it......notorious 4 problems

[datzenmike]

couple months ago i was driving at night and the speedo/temp/tach went dark but the clock and the gas gauge are still lit.  i hit a bump and they came back on, but the next time i drove they were out again.

 

 

The dimmer switch failure would affect ALL the illumination lamps in the dash even the heater, cig lighter, radio and the automatic shifter console. (if you had one) If just a couple of the gauge lights are off & on, then a loose connection to only these bulbs. It won't be a fuse, headlamp switch or the dimmer switch or all would be affected.

 

Look for a burned or damaged printed circuit run (either power or ground) that is common only to these two gauges.

[DotSoon]

I've wiggle and jiggled and cleaned things.  ill pull it out again and check the circuits more closely.  if it is a damaged circuit what would be the course of repair?

 

thanks again for all the input.  

 

everything works except the tach/speedo/temp gauge.  

[Lockleaf]

pull your gauges out. Inspect that printed circuit for burn damage. If there is damage, you can repair printed circuits with the goo used to repair rear window defroster lines.

 

About half way through the episode linked below, they do that exact repair to a gauge bezel. They also show how to diagnose gauge bezel problems. It's abb episode of trucks from power block tv

 

http://www.powernationtv.com/episode/TT2014-19/super-dually-the-payoff

[DotSoon]

pull your gauges out. Inspect that printed circuit for burn damage. If there is damage, you can repair printed circuits with the goo used to repair rear window defroster lines.

 

About half way through the episode linked below, they do that exact repair to a gauge bezel. They also show how to diagnose gauge bezel problems. It's abb episode of trucks from power block tv

 

http://www.powernationtv.com/episode/TT2014-19/super-dually-the-payoff

thanks Hall Monitor, that video gives a good visual for what ill have to do if there is a broken trace.  I'm hoping its that or just a bad ground.

[DotSoon]

electrical gremlin update:  the instrument panel is good.  checked continuity on the circuits for the lights and everything is good.  also did the same for the wires that are for the lights and there is continuity but to as much as on the dash gauges.  i also checked on the light switch itself for the wires that run to the instrument panels and the continuity read a negative number----- I'm not sure if that is normal or not.  

 

so I'm still dark on the right half of the gauges.... it'll be a couple days before i can dig back into due to it being my daily driver and I'm back on shift.

[datzenmike]

If some of the lamps stay lit then of course the wiring and the switch are good.  Has to be... can't have some on and some off. The problem has to be in the instrument cluster. The ones that are off and on likely share a common ground or power run on the printed circuit.

 

All gauge cluster illumination lamps are powered from the 7 and 8 pin on the plug between the speedometer and the tach on the back of the gauges. As some lamps work and some don't it can be safely assumed that this plug is properly connected. The problem (as described) has to be in the gauge cluster.

[DotSoon]

If some of the lamps stay lit then of course the wiring and the switch are good.  Has to be... can't have some on and some off. The problem has to be in the instrument cluster. The ones that are off and on likely share a common ground or power run on the printed circuit.

 

All gauge cluster illumination lamps are powered from the 7 and 8 pin on the plug between the speedometer and the tach on the back of the gauges. As some lamps work and some don't it can be safely assumed that this plug is properly connected. The problem (as described) has to be in the gauge cluster.

 

makes sense.  ill attack it from the front side now.  pull the gauges out of the instrument cluster and see if everything is as it should be.

 

thanks for the insight.