Instrument and dash lights suddenly malfunctioning

[Mosin]

Hi All,

Out of the blue the dash and instrument lights on Pandora (1976 D26-RT Brave) have started malfunctioning. All of the instruments themselves, headlights, and turn signals are working... just not the dash and instrument lighting. I first noticed the fuel and oil press gauge light was out and was going to check the bulb, but the next time I started the rig none of the dash or instrument lights would come on, except for the right turn signal indicator light, which is now glowing bright (!). There is clearly some power getting to the panel as a few of the instrument lights and dash lights show a bit of glow. I checked and cleaned the fuse but that didn't remedy the problem. I gently pushed on the harnesses and connectors at the rear of the panel to see if something was loose, but this didn't effect anything. I really don't know where to start.  i?? Obviously a wiring diagram of the 76 dash would help, but I don't have one. Any ideas would be most appreciated!

[LJ-TJ]

Check the down load section of the group and see it there is a "FREE DOWN LOAD " Dodge Motor Home Chassis  Manual 1974-75 Manual Supplement. Models RM-300,RM-350 RM-400,M-300,M-400,M-500. That's the manual with your instrument panel in it. If you don't have any luck I'll check I think I may have a scan of it.

[Rogerslvnv]

Dash lights usually run through your headlight switch, if all your gauges are working and it's only the lights(all of them) that are acting up, it could be in that switch. Yes, it is possible for the headlights to work fine and the dash light circuit to be screwed up.

[RV Mech Tech]

Mosin- check your ground for the dash lights- it will probably be in the harness connection and ground somewhere in the dash and this connection may be corroded or loose - you can bypass the factory ground and run a new wire to the dash cluster  to see if that solves the problem - check also for a resistor in the dash light circuit when you view the wiring diagrams as T-J  and Mark have suggested - some of the early Chrysler cars had the same problems in the 60's and 70's with bad grounds and wiring - usully if lights are working but they are dim then the ground is usually a fault- just like a dim headlight.    Hm?

[JDxeper]

On my 78 all the dash lights didn't work, water had gotten into the pull out head light switch, which also operates the panel lights.  I replaced the head light switch, a plug in  pig tail affair, about $12.  a little lever on the under neath side releases the pull out portion and then the nut on the front unscrews to release the switch mechanism.  Bottom line, I just replaced the head light switch and fixed the whole works.

[DaveVA78Chieftain]

While your rig is a 76, it most likely is a 75 chassis.
Chassis Wiring was essentially the same for 74 up.
The new style dash was used from 74 up. 
You can use the wiring diagram (last 2 pages) in the 74-75 supplement available from the store
(http://www.classicwinnebagos.com/forum/index.php?action=store;cat=42; top right book).  For full coverage, you also need the 69-77 Parts/service manual.
Instrument panel circuit is on the last page (83).  Dash lights are circuit F52A-18OR.  Dash panel connector is shown on top right of page.  It connects to the connector behind the ammeter gauge (see picture).  There are several new style dash panel pictures in JD's gallery.
(http://www.classicwinnebagos.com/forum/index.php?action=mgallery;sa=album;id=101)
[smg id=1100]
[smg id=1099]
Back of Fuel/Oil gauges are shown in 2nd pic.
The black button like thingy's are the dash light bulb holders.
The lights above the removable plastic dash panel where added by Winnebago and are not reflected in the Dodge data. 

[Mosin]

Many thanks for the responses! I can't tell you how much I appreciate the info/leads.  I'll get the 74-75 supplement, print out these excellent recommendations, and have at. Hopefully a successful follow up post is forthcoming!

[Mosin]

After purchasing the supplement, reading back over your helpful comments/suggestions, and pondering the condition once again, I think I'm either looking for (in no particular order):

1) A loose or corroded F52A-18OR wire/connection on the dash panel side. Since the Gear Shift Indicator Lamp (also F52A-18OR) is still working perfectly and shines bright, and as mentioned, some of the instrument lights still glow weakly, it seems there is at least some power in the F52A-18OR lead... just not enough power, or not enough ground at the dash panel...

2) A loose ground wire or wires. According to the diagram in the supplement there are two ground points on the panel, one marked Auxiliary Ground Terminal, and the other marked GND. As per RV Mech Tech's suggestion I will try a separate ground wire at both of these points to see if that makes a difference.

3) A bad Instrument Panel Voltage Regulator (?). I have no idea if the IPVR controls voltage to the instruments themselves, or to the lights. Either way, I can't seem to locate it on the diagram. Can anyone rule the IPVR out based on the condition described?

I can't wait to get to the rig and experiment! Many thanks again!!

[Mosin]

you can bypass the factory ground and run a new wire to the dash cluster  to see if that solves the problem - check also for a resistor in the dash light circuit when you view the wiring diagrams as T-J  and Mark have suggested -

Goccha on the ground check and new wire, but I'm not sure what/where to look for the "resistor in the dash light circuit"  i??

Dash lights usually run through your headlight switch, if all your gauges are working and it's only the lights(all of them) that are acting up, it could be in that switch.

Bottom line, I just replaced the head light switch and fixed the whole works.

Good to know it's a relatively easy and inexpensive fix should it come down to the headlight switch  I didn't think it was the switch initially since the dimmer still functions (i.e. controls the few instrument lights that still glow weakly) but this just ight be the culprit. I'll take it sequentially and report back!

[RV Mech Tech]

Mosin - sorry, I should have been more specific- your panel voltage regulator is what I was referring to - some vehicles of those years had a simple resistor, some actually had a voltage regulator such as yours- when electrical troubleshooting circut(s) always check for the basic circut- check for proper voltage, continuity of the conductors and proper current flow (amps), and resistance- if any one of those three are missing or are not working correctly you will have those problems - my analogy in fixing anything has always been three questions- WHAT is the problem?   WHY is it a problem? and WHAT can be done to solve the problem(s)  -  you are going about it the correct way by getting the diagrams and checking the coach out with the diagrams in hand- you would not believe how any mechanics try and solve a problem (especially electrical) without diagrams and end up being 'parts changers' and costing the owner of the vehicle mega-bucks and pay for their learning process-  electrical problems are usually very simple to solve as long as you have the tech info - isn't it nice to have this information available on this website? - this is really where you see how hard the administration of CWVRV  has worked to bring this repair info to the members not only to repair their vehicles/RV's but also to repair them correctly and most of all to save money !       

[JDxeper]

If it were a bad regulator none of the gauges would work. The regulator works with an intermitten voltage pulse and averages 5 volts.  still check your light switch.

[Mosin]

   AS ALWAYS, YOU GUYS ROCK 

It was a bad ground. I alligator-clipped a test ground wire from the ground post on the rear of the panel to the steering column bolt and VOILA... all dash lighting is perfect once again. 

Tomorrow I will wire a permanent ground to the post, and reinstall the dash panel, steering wheel, and seat. In the end I guess I didn't have to go through all that trouble (removing the dash panel) but it sure makes inspecting the dash wiring a breeze.

Many thanks again for everyone's assistance/responses!

Cheers,

Mosin

[JDxeper]

Grounds are always a good thing.   

[Oz]

Historically speaking, the majority of electrical problems encountered and solved on the forum, before yanking any components, check the grounds first, because they have been the source of the problem approximately 75% of the time.  Quite a few members have spent countless hours of frustration, and money, replacing components all along the troubleshooting route, only to find the problem was a bad ground. 

[Froggy1936]

The dash light resistor (misnomer) Dimmer is whatever dims all the dash lights for driving usually by rotating the headlight switch knob sometimes a separate knob I have seen this feature fail and do odd things to the dash lights if it is part of the headlight switch it requires replacement of the complete H/L switch  Frank

[RV Mech Tech]