53 Roadmaster electrical question

[53buickconvert]

During my restoration, I completely rewired the Buick. This included the wiring for the window cylinders, lights, convertible top, etc.

 

Now , everything works except the brake lights. The brake light switch has been checked and jumped.

 

The tail lights come on with the light switch selected on. The brake lights don't come on with the pedal application but do come on when the light switch is selected to the parking light position. ?

 

I have attached the schematic for anyone who might want to make an attempt at figuring out the problem.

 

 

Tim

[Ttotired]

Many things, but lets start from the start

First, I am afraid that the tail lights have no relevance as the bulb should have 2 filaments in them (check this) they are 2 bulbs in one, so 1/2 can work, and the other 1/2 not (if you get me)

Now, Check for power at the stop light switch (by the way, if you do not own a test light, go buy one first and dont get the LED one, get one with a bulb in it) no power, look at the fuses, got power, the next step is the flasher switch. Turn one of the flashers on, does it flash at the back, yes = bulb OK, wiring from the flasher switch to down the back OK (check both sides)

Check the colour of the stop light switch wire going into the steering column (with the stop switch bypassed) does it have power? yes = Flasher switch is faulty, NO = wire broken or faulty connector between the sop and flasher switches

 

I am assuming that the earth connections to the tail light assemblies are good as well.

Do all this testing wit a test light, a multimeter or LED test light can (and will) tell you lies due to needing virtually no current to work meaning a faulty wire can test ok with no current but put a light on it and it will show the fault (light bulb draws current)

 

 

[53buickconvert]

The Directional signal lamp operates fine both sides which is separate from the combination tail and stop lights.  The problem is that the only way to get the stop lights to come on is by selecting the parking lights on. When driving lights are selected on, the brake lights go off.  There is power to the brake light switch. Grounding has been checked but I guess I could check it again.

[Ttotired]

OK, first, I think you have the front and rear park light wires connected wrong on the headlight switch

Front park lights come on in the park position only and rears stay on in both park and driving positions.

I am not sure your understanding that there are 2 globes in one with your combination stop/park lights

The diagram your looking at does not show this well at all, but if you look at the bulb, you should have 2 filaments suspended on 2 sets of arms inside the bulb.

If you have connected it up at the tail light like it looks like in the drawing, then you will have joined wire 18N and 18BC at the back of the globe holder, this is incorrect, the drawing is not that good, should be 2 wires going into the globe holder with 2 contacts inside, the bulb should have 2 contacts and the bulb earths through the metal case

Edited August 2, 2016 by Ttotired
more content (see edit history)

[old-tank]

Your service manual should have a separate detailed diagram of the turn signal switch and how the brake lites are integrated.

[Ttotired]

Yep, I assumed that the indicators and brake lights worked on the same bulb, but when you look at the wiring diagram above, it shows that the

indicators are separate, so the brake lights have nothing to do with the indicator switch.

Same fuse that supplies the flasher unit supplies the brake switch, and the output from the brake switch goes to the fuse box, then out to the rear, but this is just a junction point, no second fuse.

Anyway, might have fixed it now, no followup posts of increasing frustration

 

 

[53buickconvert]

I ensured all four light housings in the back were fully grounded followed by tracking back the brake light wire to the fuse panel. I had mistakenly connected the brake light wire to the light switch.  Not sure how this happened.   It took a while to figure this all out but it works now.

 

thanks for all the 

[Ttotired]

Your welcome

Glad you found it, Finding stuff like this is what I do daily