Brake Light Switch or Turn Signal Switch?

[jlhunsinger]

1972 Dart Swinger. The car has been converted to a 440 with 727 ratchet shift

Having trouble with brake lights, specifically none. I took the rear light assemblies out and cleaned them thoroughly but have not yet reinstalled.

I am using a low voltage circuit tester and verify that the 20A fuse is hot for the brake lights.

I probed both wires to the brake switch and am showing that neither is hot, with or without the brake pedal depressed.

I took apart the steering column to the TS switch to see if I could follow some of the test procedures on other forums but I've confused myself a bit now.

I get no flashing from the blinkers, when I engage either side.

I get no emergency flashers when the switch is on. If I have either blinker and the emergency flashers engaged, I get blinking flashers (remember I only have the front lights in right now, was not getting power to the connector in the rear when I removed them).

With the Emergency switch off and the L blinker on I only show two wires as hot, R and G
With the Emergency switch off and the R blinker on I only show two wires as hot, R and br

With the Emergency switch on and the L Blinker I show hot at (R,Y,W,P,G,br)
With the Emergency switch on and the R Blinker I show hot at (R,Y,W,br,G,P)

Do not show hot anywhere with key off and all neutral.

Can anyone send me in the right direction as to what to test next? I'm certainly not an electrically savvy guy or I would have been able to dissect the loads of information you all have already provided. Thank you in advance.

 

[blown71duster]

jlhunsinger,

On your brake lights, you should have power to one side of the brake switch coming from your 20 amp fuse (pink wire I think). Then when you apply the brake pedal and close the switch contact it should feed the white wire going into your hazard flasher switch. Then finally feeding into the turn signal switch coming out on brown(right rear brake) and Dk. green (left rear brake)

You should have power coming from emergency flasher (pink wire at hazard flasher switch) and power from the signal flasher (red wire at turn signal switch )

Power feeds coming from the turn signal switch :
Right front -Tan
Left front- Lt. Green
Right rear - Brown
Left rear- Dk Green

You can check inputs/outputs from the column switches at the C1 19 plug . It is the 8 cavity plug at the base of the column. All the power inputs and outputs listed above , also includes a black wire feed for the horn.

 

[RedFish]

The above is correct. Very first thing is get 12 volts to the brake lamp switch. fault could be rusty fuse clamp or connectors in the fuse box. One member found a fuse broken underneath its end cap. To touch it with a test probe showed good but lack of pressure from that probe left it open again.

 

[jlhunsinger]

Thanks Fabo. I reinstalled the taillight assemblies yesterday and had different results with the blinkers/flashers but still nothing to the brake lights. I will be away from the car today but will start back asap and try what you mentioned.

Thanks again!

 

[jlhunsinger]

Its been a while and I've finally got my Dart back (moved and had it in storage). Time to revisit this problem.

I spent some time today playing with the wiring. Again, I'm not savvy on electrical but will describe what I've got so far.

I do have 12 volt to the pink wire on the brake switch. I ran a jumper wire between the pink and white to bypass the switch (my idea of testing if the switch was the problem) but did not show brake lights on when I did this.

When I took the wheel off and started analyzing the turn signal switch I figured out if I jumper between the red and white terminations from the left side (turn signal, not four-way switch) of the circuit, I get tail or brake lights. I'm not sure which is which. The red wire is 12 volts with the key on, but dead if off which I think it appropriate.

The pink wire on the right side is always 12 volt.

From the brake light switch, am I understanding correctly that the white wire goes up to the turn signal switch? If this is this case, is there really no way to rule out/ bypass the turn signal switch in the column to see if the brake lights work at all?

I'll ask in advance for your patience. Thanks for any additional feedback and I appreciate tips on how to rule out one issue and move to the next possible cause.

 

[jlhunsinger]

When I took the wheel off and started analyzing the turn signal switch I figured out if I jumper between the red and white terminations from the left side (turn signal, not four-way switch) of the circuit, I get tail or brake lights. I'm not sure which is which. The red wire is 12 volts with the key on, but dead if off which I think it appropriate.

I have been getting my wife to spot the lights for me while I monkey with the wires. As I was typing the post I came to the realization that I've been thinking it was brake lights when I jumped white-red on the left side, but is that maybe just tail lights?

With the headlight switch "on" I have two working headlights, both amber lights in the front are lit, both front marker lights work. In the rear I have two tail lights working and driver side marker light works. Passenger side is out (possibly a bulb I haven't noticed this before now).

While the headlight switch is "on" if I jumper between the red and white terminals on the turn signal side, my wife says that the left tail light goes off and the right remains unaffected.

 

[67Dart273]

i do have 12 volt to the pink wire on the brake switch. I ran a jumper wire between the pink and white to bypass the switch (my idea of testing if the switch was the problem) but did not show brake lights on when i did this.



From the brake light switch, am i understanding correctly that the white wire goes up to the turn signal switch? If this is this case, is there really no way to rule out/ bypass the turn signal switch in the column to see if the brake lights work at all?

ok

I have been getting my wife to spot the lights
While the headlight switch is "on" if I jumper between the red and white terminals on the turn signal side, my wife says that the left tail light goes off and the right remains unaffected.

This specific result indicates a GROUND problem.

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HERE IS the deal.

TURN SIGNALS

Flasher gets power "key on" and feeds flasher output into the TS switch

Brake switch should ALWAYS be hot, and output feeds into the (white) TS switch

Left and right TURN and BRAKE are same wires, one wire for each side, come OUT of the TS switch, and go through the KICK PANEL connector at the left, then under the wire channel, off to the rear of the car. That connector is a good place to probe to do checking. If you have power there, but not working at the rear, either the harness is pinched / cut going to the rear, or you have bulb / socket problems

THEN you have ONE wire for tail lights for both sides going to the rear. This comes off the headlight switch, and also powers the rear side markers.

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FIRST thing I'd do is look up the wiring diagram, go here for a shop manual and wiring diagrams

http://www.mymopar.com/index.php?pid=31

(By the way some of the service manuals there came from the guys here at FABO
=================================

Next, tear apart the rear bulbs and sockets, scrape them clean, inspect, test and replace bulbs. If you cannot get them to ground, solder ground pigtails to the socket shells and run an extra ground wire from the socket shells to a ground bolt

=================================

Test the tail / marker lights, and do "wiggle" tests to see if the grounds look OK

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Do a "wiggle test on the TS switch. Wiggle the 4x flasher switch, and the TS switch to be sure the 4x is off and the TS is "centered." Have your wife again watch, as you jumper the brake light switch, and see if you have brake lights. "Wiggle" the TS and 4x switch to see if they work, one left, one right, centered, etc.

If they seem to work, turn the tail on / off they should not go out as you describe. If one / the other does, you still have grounding problems
===================================

If functions don't seem to make sense, look up the colors for the kick panel connector, and probe that with a meter or test lamp to see what is going on. If you are getting power there when you should, then you likely still have bulb or socket problems.

Don't discount bulb problems. Bulbs can be a *****, simple as they are. They can be intermittent, and they can short across internally. That is, tail light power can "transfer" to the brake light filament, and vise versa.

 

[67Dart273]

Below are from pages 8-150 and 8-151 of the 72 service manual

The very top one, white is switched brake power coming "from" your brake switch

Next one down, 18BR, means no 18 gauge wire, BRown goes to right rear stop/ turn

Next one down, 18DGN (Dark GreeN) goes to left rear stop / turn

Now look at the kick panel connector top photo. Terminal no 8 is BRown, is your right rear

Terminal no4 is Dark GreeN, the left rear

 

[jlhunsinger]

Thanks for the feedback. I will try the tail lights again. They are new bulbs but the sockets themselves were in bad shape. I've downloaded a manual now and was working from the wiring diagram previously.

 

[jlhunsinger]

Alright so I did some additional disassembly under the column yesterday and have accessed the turn signal switch connector. I unplugged the battery and tested for continuity of each prong at the connector, compared to each place they terminate on the switch. (Forgive me if my terminology isn't exact).

I did all of this with the turn signal switch centered and flasher's off.

My next question is there anywhere I can find a diagram of the switch itself, with the wire colors and where they are placed. These things are faded and grimy so I can't tell if white is tan or brown etc..

I was able to get continuity at the switch for every wire. Shouldn't the white wire at the connector also show continuity to the two rear light wires...dark green and brown wasn't it?

Since I verified the brake light switch was hot to one side I assume there is a hiccup (the TS switch) channeling the voltage to the rear ground. Since the Blinkers work I know the tail light assembly is grounded.

 

[Yote]

Don't know if it will work for your situation, but one thing I have done to trace wires quicker is to remove battery and hook it directly to wire in question. Such as tail light pigtail. Then work your way back testing for power. Sort of reverse tracing. Be sure to add a fuse in circuit next to battery for protection while testing.
Yote