No Brake Lights

[Mark_B]

Hi All,

I was hoping you can help please.  The brake lights don't work on my 70 Challenger.  The side lights work though and there is current at the brake light switch.  I've looked over the fuses and I think they're ok.  I've used a multimeter to check the green wire going into the light cluster and that also has current.  I've checked the bulbs and they're all fine.

What do you think this could be please?

Thanks for any help you can give.

[chargerdon]

Do the tail lights light when headlight switch is on ?
Do the turn signals work in the rear?
Do the tail lights blink when the 4 way flasher is turned on ?

I do believe that the brake light switch is a ground switch not a power switch...   Have you checked that the brake pedal is making contact with the switch ?  Have you checked it with a multi-meter for continuity when the brake is depressed ?

[Dakota]

Grounding is often a cause for these kinds of issues.  The original light housings for my 70 grounded through the light housing mounting studs to the body of the car.   Add new paint or rust and this connection can fail.   The replacement rear light housings that I installed came with a separate ground wire. Having read lots of posts about bad grounds causing problems, I ran a dedicated ground from near the battery to this supplemental ground wire on the replacement light housing.

The easiest way to check if you have a bad ground  is to run a temporary wire from your "-" post on the battery to the light housing and see if things improve. 

You may not have a grounding issue, but at the least you can quickly eliminate this as a source of your problems.

[Mark_B]

Yes, the tail lights work when the headlamps are on.

Yes both turn signals work fine

Yes, the brake pedal is making contact with the pedal.  I have pushed the brake switch in manually and it doesn't work either.

I have checked the brake switch with a multi meter and it has a current.

[Mark_B]

The easiest way to check if you have a bad ground  is to run a temporary wire from your "-" post on the battery to the light housing and see if things improve. 

Thanks, I'll give that a go.

[Chryco Psycho]

The power goes from the brake light switch up the column to the turn signal switch which splits the power to the left & right rear so the brake light can be interupted for signal so if the power goes to the column plug OK but doesn't return from the turn signal switch then the turn signal switch is faulty which is common .

[chargerdon]

to check the turn signal switch...find the wire going UP to the switch at the flat connector...  strip back a little of the insulation on the turn signal side and check for power...   then find the return wire from there that goes to the brake lights and strip some of its inulation and test for return power...   

[Mark_B]

Thanks for this information, I'll have a look tomorrow when it stop raining.

[HP_Cuda]

Is the brake light switch positioned correctly?

Remember it's a reverse switch.

[Mark_B]

Is the brake light switch positioned correctly?

Remember it's a reverse switch.

Hi,
Yes the position is correct.  I've pushed the switch in manually with my thumb and it doesn't work either.

[Chryco Psycho]

to check the turn signal switch...find the wire going UP to the switch at the flat connector...  strip back a little of the insulation on the turn signal side and check for power...   then find the return wire from there that goes to the brake lights and strip some of its inulation and test for return power...   

Why strip wires , you can just probe at the connector ?

[Katfish]

 My turn signal was bad, and the symptoms were no brake lights

[Mark_B]

Thanks for that article.

So I earthed the rear lights on the battery terminal and that didn't work.  Under the steering column the wires are a mess, much of the wires are taped up so it's difficult to see where they go. 

[chargerdon]

that sure is a rats nest...   makes it difficult...  but u still have to do it to determine if there is a wiring problem, or the turn signal switch..   

[Chryco Psycho]

why not just test at the connectors .