Instrument lights not working - HELP!

[Troy P.]

Re: Instrument lights not working - HELP!

In addition to the grey wire coming off the rheostat there is a black wire that goes to the light in the cigarette lighter. That lamp is lighting up and changes brightness as the rheostat is turned. This plus my testing of 6V between the red hot wire and rheostat lug on the switch shows power properly through the switch.

From the instrument light lug on the switch to each instrument can (ground) I get 6V, with the exception of the speedometer housing which does not mount on the panel reinforcement and has a black ground wire for each bulb. No power showing at the copper tips in the bulb sockets.

Seems to say there is a discontinuity in the grey wire between the switch and they first bulb.

[Troy P.]

Re: Instrument lights not working - HELP!

I neglected to address the bulb issue. The bulbs have numbers like 52. Are all 52s 6V or do they make the same bulb number in different voltages? In any case with no power getting to the sockets doesn't seem like the bulb would be the issue.

[Troy P.]

Re: Instrument lights not working - HELP!

I was wrong about the speedo housing being connected to the panel reinforcement. It is not. All the other gauges and clock are though.

Each light in the speedo housing has its own ground wire. The bulb sockets have two wires whereas all the other just have one and the panel reinforcement is the ground plane.

[Richard M.]

Re: Instrument lights not working - HELP!

I neglected to address the bulb issue. The bulbs have numbers like 52. Are all 52s 6V or do they make the same bulb number in different voltages? In any case with no power getting to the sockets doesn't seem like the bulb would be the issue.

Spec for a #52 is a 14.4V bulb. No, the bulb number IS the spec. Never heard of different voltage for same # bulb.

I was wrong about the speedo housing being connected to the panel reinforcement. It is not. All the other gauges and clock are though.

Each light in the speedo housing has its own ground wire. The bulb sockets have two wires whereas all the other just have one and the panel reinforcement is the ground plane.

Verify sockets ground wire has good ground. Continuity test them between known ground and socket base wall.

My gut is telling me those separate black ground wires are not properly grounded.... to ground. Could there be a separate wire going to those that hasn't grounded yet? I recall on later switches there is a separate black ground that must be attached to the back of the HL switch. Is that black wire on 1954 HL switch also?

In addition to the grey wire coming off the rheostat there is a black wire that goes to the light in the cigarette lighter. That lamp is lighting up and changes brightness as the rheostat is turned.

OK, this means the HL switch is good.

This plus my testing of 6V between the red hot wire and rheostat lug on the switch shows power properly through the switch.

I'm getting confused again. Both of those points with respect to ground, right? Not between EACHOTHER, right?

From the instrument light lug on the switch to each instrument can (ground) I get 6V, with the exception of the speedometer housing which does not mount on the panel reinforcement and has a black ground wire for each bulb. No power showing at the copper tips in the bulb sockets.

Yes this seems like a open in the harness somehow. Hard to image that's the case though. Your meter NEG probe is on good ground when testing , right?

Seems to say there is a discontinuity in the grey wire between the switch and they first bulb.

[Troy P.]

Re: Instrument lights not working - HELP!

There is a black wire that is on the side of the switch. Only wires on the back are red (hot) and brown (radio light). Radio light was not originally controlled by the dimmer but everyone assumes it should be and wires it to the rheostat terminal with the instrument and cigarette lighter light. The radio has its own switch that controls the power and light.

I will get back to testing tomorrow and respond in more detail.

[Troy P.]

Re: Instrument lights not working - HELP!

I don't know what I did but the instrument lights are now working. The wiring diagram shows after the grey wire leaves the switch it meets in a major junction with every wire heading to individual bulbs. Perhaps moving the harness around caused that connection to reconnect.

The bad news is my rheostat used to adjust the brightness, as seen by observing the cigarette lighter lamp yesterday, but now does not. It only provides power at one location when turning the switch. But it is the brightest location. So what caused that all of a sudden? Damaged in my testing? I did put my multimeter probes from hot on back of switch to the rheostat lug to see if power was getting through the switch.

Now on to lightbulbs. Since panel lights are so dim it was recommended to me to use bulbs with more candlepower than spec. Can that actually be done?

The owner's manual calls for 51, 52 and 55 bulbs. ST-12 varies somewhat calling for a 53 in the ignition switch. Are 51, 52, 53 and 55 all 6V or is a 53 12V? ST-12 shows the 53 used commonly in 1955-62 which are 12V cars. So that makes me think its a 12V bulb and ST-12 has a typo.

Only other problem is in the right turn signal. It flashes slower and the arrow is less bright than the left signal. I will pull the right rear bulb and clean contact surfaces and see if that solves the problem. Any other ideas?

[Mark F.]

Re: Instrument lights not working - HELP!

Troy,

Have you discussed any of these difficulties you are having with the harness manufacturer?
The downstream gray wire connection problem (hence, no continuity to the bulbs) seems kinda lame for a brand new harness, eh?

[Troy P.]

[Troy P.]

Re: Instrument lights not working - HELP!

Thank you all so much for putting up with me and my electrical issues! Very helpful.

Everything is working now except... The remaining issue is the right turn signal flashes the parking light and taillight too fast. Furthermore when the parking or headlights are on the turn signal brightness difference at the right tail light is barely discernable. The flashing is more obvious when the lights are off. I have checked to make sure the bulb is 100% at both filaments. It seems to me the symptoms are showing a lack of electrons to the brighter filament in the bulb via the turn signal switch.

I have cleaned the sockets and bulbs for the right front and both backs to make sure they have a good connection to positive and ground.

In other posts on the Discussion Board about the fuel sender not working properly (fuel gauge bouncing around when the right turn signal is on) it was suggested to add a ground wire from the fuel sender to the chassis as the fuel sender and rear tail lights share the same ground wire. I did that. I mention that step but don't see why is would cause the current (sic) issue. But it might be related.

[Troy P.]

Re: Instrument lights not working - HELP!

Now that I think about it the advice to add a ground from the fuel sender to the chassis to supplement the rear harness ground may not apply to 53-55 6 cylinder cars. I can't think of an electrical path through the chassis. I think the only ground is the engine block and the engine is isolated from the chassis. Later cars had ground straps from the engine to the chassis but the 6V cars do not. So I'm guessing adding that ground may have caused, rather than solved, a problem. I guess I should open the tank cover and undo that wire and see if it solves the problem with the left turn signal.

[Richard M.]

Re: Instrument lights not working - HELP!

Troy, I wouldn't think adding that sender ground is your issue. Maybe you have different bulb types between left side and right side. The candlepower difference could cause a different flash rate and brightness. The other reason could be unclean ground contacts where the ground wires and housings attach.

I've not worked on a '54 before but just thinking of possibilities.

Also, do your Inst lamps now dim with the knob turning? You said everything is working now but previously you said they didn't dim like the radio lamp.

Rich

[Troy P.]

Re: Instrument lights not working - HELP!

Worked on it all day but I'm relieved to have just recently found the problem with the right rear light!! Whoever assembled the wiring harness had the tail light and turn signal wires reversed in the light socket. So the turn signal was flashing the wrong element in the bulb. That caused it to flash too fast and too dim.

I believe the rheostat is supposed to work up to about 3/4 of a turn of the knob. What I have now is all the way left is off. Slightly to the right is full bright. A tiny bit farther to the right and the lights dim a bit. A tiny bit farther yet they are off again. So all together I have maybe 10 degrees of function. What do you think?

Fingers crossed for no more problems.

[Richard M.]

Re: Instrument lights not working - HELP!

Troy good find on the swapped wires. That'd do it for sure.

Sorry can't help with that dimmer. Unfamiliar with that switch, but to me it doesn't seem to be operating correctly.

Rich