Headlight Switch & Dimmer Switch Issue

[ToddMcF2002]

1969 GTX. My Dimmer switch doesn't seem to work and my dash lights are fairly bright. However, when I turn the headlight switch on all the way the dash lights go out. The dash lights stay on unit the last millimeter or switch travel which is where the headlights go on. Looking at the diagram there is a wire between the dimmer and headlight switch. Anyone have any experience / advice here before I pull the panel? Is this expected behavior with a bad dimmer switch?

 

[davek]

Sounds to me your dimmer switch needs to be rebuild. I had one that the big spring was lose and that was the problem with my dash lights only working some of the time. There is a member that rebuilds them maybe PM him and ask what he thinks.

 

[davek]

https://www.forbbodiesonly.com/mopa...board-switches-wiper-dimmer-headlight.202892/

 

[ToddMcF2002]

Thanks! Are the aftermarket ones sketchy? I’m thinking of grabbing one while I have the original sent out

 

[72RoadrunnerGTX]

"when I turn the headlight switch on all the way the dash lights go out"
Sounds more like a headlamp switch problem, as well as a possible dimmer reostat issue.

 

[YY1]

Dirty rheostat can cause that.

Try turning down the brightness and maybe moving it back and forth.

You can bypass the dimmer pretty easy with a double ended male spade connector jumper.

 

[ToddMcF2002]

Dirty rheostat can cause that.

Try turning down the brightness and maybe moving it back and forth.

You can bypass the dimmer pretty easy with a double ended male spade connector jumper.

I need to get under there to get a better visualization of how the harness is joined by L7A wire. And make sure it hasn't been monkeyed with. Do you guys take out the drivers seat to do this stuff and work upside down?

 

[YY1]

Seriously- try the rotating the dimmer trick.

That's actually very common.

I've even seen them that don't work at full panel light brightness, but work everywhere else.

Why get into that position if you don't have to?

Bypass the dimmer and see if both hi and low beams work.

Easy, and again, doesn't require that position, which I call "inverted fetal position from hell".

 

[ToddMcF2002]

Just to make sure people understand what I'm seeing I made a quick YouTube video. Please let me know what you think...

 

[devinism]

Looks like your dimmer has been bypassed already, and they either jumped it to the wrong wire or ??? Time to wrestle the switch panel out and have a good look back there. The feed for the dimmer comes into the headlamp switch on B2 (cast into the back of the headlamp switch). It SHOULD be hot at all times. In the 'PARK' position you SHOULD have power coming out of the headlamp switch on 'R', which is power out to Tail, Dash, and Park lamps. Also verify that your headlamp switch is a 5 terminal (68-69) type, not a 4 terminal (70)

 

[ToddMcF2002]

Has anyone replaced a HL switch from the back without pulling the panel? Sure looks doable if I pull the drivers seat.

 

[devinism]

https://www.forbbodiesonly.com/mopa...board-switches-wiper-dimmer-headlight.202892/

That's me!

 

[ToddMcF2002]

Thanks Devin I’m two steps ahead of you. But can I install it from behind without pulling the panel perhaps you know ;)

 

[devinism]

Thanks Devin I’m two steps ahead of you. But can I install it from behind without pulling the panel perhaps you know ;)

View attachment 1297067

Lol.... Well at least the headlight switch is handled.
I'm still pretty sure someone has 'jumped' or spliced into the paring light wire to power up the dimmer. The parking lights are designed to go out on '68-'69 MoPars when the headlights are on. That may be why the dash lights are only on when the H/L switch is in the 'Park' detent.
And as far as access?? I really can't remember. It's been 20+ years since I last crawled / contorted behind the dash on a B body. At least there's no A/C in the way.