'70 Plymouth Parking Brake Light on Dash

[MoparHonda]

The parking brake light on the dash of my '70 Plymouth lights up brightly when the key is on and the parking brake is down, as it should.

Problem is, when I release the parking brake, the light goes very dim, but does NOT turn completely off. You can't see it during the day, but it glows very dimly in the dark. Turning the headlights on and off or adjusting the dash lights makes no difference, it continues to glow dimly. (Turning the key off makes the light go completely out.)

Why?

 

[coronet68mx]

Another member have the same problem a few days ago did you made a front disk brake conversion?

 

[coronet68mx]

https://www.forbbodiesonly.com/moparforum/threads/emergency-brake-light-dim.160123/#post-911076067

 

[PurpleBeeper]

OK, check your wiring diagram and don't take my word on this, but it "sounds" like the brake light is wired "hot" & gets a ground (which lights it up) by either A)the parking brake pedal is pushed or B) the brake warning pressure imbalance switch in the brake system gets grounded by 1/2 the braking system going out. So.....it seems like the light is getting "a little bit of ground" from somewhere... a bare wire touching something, the switch on the emergency brake pedal adjusted just barely off (pull emergency pedal up & see if it goes out) or something like that.

 

[RobsRR]

I have the same problem. I did do a disc conversion. I am also using led bulbs which don't take much voltage to light up. When I pull the wire off the combination valve the dim light goes totally out. How about you any similarities?

 

[PurpleBeeper]

I have the same problem. I did do a disc conversion. I am also using led bulbs which don't take much voltage to light up. When I pull the wire off the combination valve the dim light goes totally out. How about you any similarities?

That's interesting. If you are getting "a little bit of ground" through your combination valve (hold-off/proportioning), then it makes me wonder if you might have some moisture in your brake fluid??? Dry brake fluid would not provide any ground at all.....but a little moisture in DOT3 brake fluid would do that....just wondering.

 

[MoparHonda]

Thank you for all your help, I'll check this out on Monday. Far as I can tell, the brakes are working fine, but I'll also look at that.

(I have NOT done a disk brake conversion.)

 

[MoparHonda]

Looked at this, I found an LED bulb in the light, replaced it with a standard bulb. The wire to the parking brake pedal seems OK.

I no longer see a glow in a dark garage when the brake is off and the key is on. Will see what happens next time I'm out on the road after dark.

Thank you all for your help.