Mercury Cougar Owners banner

1 - 20 of 47 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
Hi everyone Im experiencing problems with my brake lights on my 67. They dont come on when applying the brake. My tailights come.on when u turns the headlights on, and my sequentials work as work as well. I located a small fuse box on firewall but all I can see are fuses for cigarette lighter and dome lights. Your guys help is most appreciated
 

·
Registered
Joined
·
308 Posts
I suggest you check the brake light switch to see if you are getting power to the switch and then see if the contacts are closing when you press the brake pedal.

1. Disconnect the wires at the stop light switch (underneath the steering column)
2. Check for voltage on the green and red striped wire. If there is no power on this wire, then your problem is in the wiring under the dash.
3. If you have power at this wire, then check for continuity thru the stop light switch by placing and ohm meter probe into the switch leads as you press the brake pedal.
4. If there is continuity then move to the rear of the car and check your ground leads on the lights to make sure that they are clean. ( Since your signals and tail lights function, your ground is probably good)
5. Check for continuity of the wire from the taillight to the brake switch. If there is no continuity, then you will need to chase down the wire as your wire has a short or a break in the wire.
6. If everything checks out to here, then you are down to replacing the bulb or replacing the bulb housing.

But my guess is that your brake light switch is probably dead or the wires connecting to the switch are corroded.

To remove brake light switch do the following:

1. Disconnect the wiring block at the switch
2. Remove the hairpin retainer
3. Push the rod, nylon washer and bushing away from the pedal
4. You should now be able to remove the switch

Good luck and let me know if you need any more information.
 

·
Registered
Joined
·
308 Posts
What date was your 67 built? There is actually a difference in the brake circuitry for Cougars built after Jan. 2 1967 and those built prior to this date. There is an extra stop lamp relay used in the pre jan2 67 built cougars!!

First a post Jan 2 1967 Cougar (just so you can see how simple this circuit is compared to a pre Jan 2 1967)
1. Verify 12V at PJ34 circuit #37 (black-yellow) (fed from the Starter motor relay)
2. Verify 12V at CB-2 Circuit breaker
3. Verify 12V at P38 (at the brake light switch) on circuit 10A (green-red) without the brakes applied
4. Verify 12V at P38 (at the brake light switch) on circuit 475 (green-white) with the brakes applied
5. Verfiy 12V at PJ61 on circuit 475 (green-white) with the brakes applied
6. Verify 12V at the PJ76 (at the sequential main turn signal relay) on circuit #475 (green-white) with brakes applied
7. Verify 12V at each tailight with brakes applied

Note: a continuity test can also be performed with the harnesses disconnected for items 1 thru 7. Always disconnect the batttery before performing a continuity test

For a pre Jan.2 1967 Cougar actually has 2 circuit breakers and a Stop lamp relay K11. Note there are 3 seperate sections below:

I. Power circuit to the K11 relay Note, this circuit is ALWAYS HOT
1. Verify 12V PJ34 circuit #37 (black-yellow) (fed from the starter motor relay, also this is used as power input for the K11 stop lamp relay)
2. Verify 12V at CB-2 Circuit Breaker
3. Verify 12V at PJ67 on circuit #474 (Red)
4. Verfiy 12V at P83 at the K11 Stop Lamp Relay on circuit #474 (this is the switched power that will go to the brake lights)

Note: a continuity test can also be performed with the harnesses disconnected for items 1 thru 4

II.Power Circuit for the brake light switch to the K11 Stop Lamp Relay
1. Verify 12V at CB-3 Circuit Breaker ( this is fed from the light switch to the brake light switch)
2. Verify 12V at P38 (at the brake light switch) on circuit 10A (green-red) without the brakes applied
3. Verify 12V at P38 (at the brake light switch) on circuit 475 (green-white) with the brakes applied
4. Verfiy 12V at PJ64 on circuit 475 (green-white) with the brakes applied
5. Verfiy 12V at the PJ84 on circuit 475 (green-white) with the brakes applied
6. Verify 12V at the P83 (at the K11 Stop Lamp Relay) on circuit #475 (green-white) (this is the coil power to activate the relay) with the brakes applied

Note: a continuity test can also be performed with the harnesses disconnected for items 1 thru 6

III.Power Circuit for the brake light switch after the K11 stop lamp relay (all folllowing procedures must have brakes applied)
1. Verify 12V at the P83 (at the K11 Stop Lamp Relay) on circuit #476
2. Verify 12V at the PJ76 (at the sequential main turn signal relay) on circuit #476
3. Verify 12V at each tailight

Note: a continuity test can also be performed with the harnesses disconnected for items 1 thru 3

To test continuity from end to end, disconnect the battery and place a 12V jumper wire on circuit #476 and to ground on #57 at the K11 Stop Lamp Relay (this connects circuit #476 to the rest of the brake system).


Note: by default, the sequential main turn signal relay has the brake light circuitry connected to the tailights. When the turn signal is ON (left or right) the k9 (left) and k8 (right) relays switch the contacts for the taillights so that if you have the left turn
signal on, only the right brakes lights activate, and vice-versa for a right turn, only the left brake lights illuminate.
 

·
Registered
Joined
·
12 Posts
I just started having the same problem all of a sudden - worked one day then next day not! Glad I was having a friend follow me to a show else I would not have known and perhaps been rear-ended! Bought a new switch at NAPA assuming it to be the prob cause, but COULD THEY HAVE MADE IT ANY HARDER TO GET TO???!!! Is there a trick secret? Appears front seat will have to come out in order to even SEE the daggone switch well!!! sigh... 65 and not as limber as used to be - lol.
 

·
Moderator
Joined
·
10,978 Posts
Coachjack likes to make everything really complicated. Wow.

First, disconnect the battery.

The brake lamp switch is the high fail item, followed by the wiring to the brake light switch. You can get on your knees, hopefully with something soft under them, and look at the brake light switch just above the steering column. There's a single spring clip holding it in place. Pull the clip, and the master cylinder rod (or power brake booster rod if you have power brakes) ROTATES to remove from the pin on the brake pedal.


Remember, rotate the shaft to remove it. Do not try to pry it straight off or you will bend or break something.

The brake light switches sold by the typical auto part stores are often misidentified. They will often give you a non - power brake switch for a power brake application. The switches are not interchangeable. Call Don Rush for best results when buying the switch.

Be sure the bulbs in your tail lamps are #1157 and not #1357. The #1357 bulbs will cause the switches to burn out even more rapidly.
 

·
Registered
Joined
·
308 Posts
Royce,

Complicated? No to the contrary, very thorough. I've seen to many people go straight to replacing everything instead of troubleshooting and isolating the problem. And more often than not, they needlessly replace items and throw away money only to find out that the same problem exists!

You may continue with your regularly scheduled program.

Coach Jack
 

·
Moderator
Joined
·
10,978 Posts
Actually I am advocating making two checks before buying anything -


1. Jumper the wires at the switch. When the brake lights come on you have verified 100% of the wiring.


2. Ring across the switch with an ohm meter. You can tell if it is working or not easily.


3. Then order the replacement switch.


Never, ever replace anything until you know what is wrong. With Cougar brake lights, it's normally the switch, or a broke wire on the connector at the switch.
 

·
Registered
Joined
·
308 Posts
Royce,

Did you read my very first sentence in my first reply ?

I suggest you check the brake light switch to see if you are getting power to the switch and then see if the contacts are closing when you press the brake pedal.
The rest of my information provides all of the detail of the 67 brake light circuitry of which there is a early model and a late model design.

You can take it or leave it with this information

Coach Jack
 

·
Registered
Joined
·
11,950 Posts
I agree - having a very thorough listing of all the points to check makes it easy to do most troubleshooting in one shot if it ends up being more involved than just the typical stuff. It beats trying things back and forth.....worthy of a stickey as a matter of fact! Lights seem to be the most commonly fought battle on here......
 

·
Contributing Member
Joined
·
1,880 Posts
If I could add one small point.

Some of these offshore brands have very stiff springs. It can cause a sort of a delayed activation of the brake lights, such as in slow traffic (stop and go) you can feel the brakes engaging but your brake lights don't come on until you press a little harder.

A good test that I found is, hold the switch in both hands with thumb and index fingers, use your thumbs as leverage and try to compress the spring. If you can, buy it.


I agree with Royce ,you should buy from a buisness that knows Cougars.
 

·
Registered
Joined
·
172 Posts
I just started having the same problem all of a sudden...Bought a new switch at NAPA assuming it to be the prob cause, but COULD THEY HAVE MADE IT ANY HARDER TO GET TO???!!! Is there a trick secret? Appears front seat will have to come out in order to even SEE the daggone switch well!!! sigh... 65 and not as limber as used to be - lol.

I agree, not easy to reach!



I placed a sqare cushion on the driver's floor (seat backed to its max) and laid down on my back, face looking up under the dash with back of my head laying against the transmisson tunnel. Right arm was introduced first under the dash while I was gently rotating on my left.
Cushion was thick enough (2" thick) to reduce pressure of door sill on bottom of my back, so I was ± comfortable and could last there for quite a while before being in deep pain!
I used a flash light (frontal would do I guess) to see what I was doing.


Oh BTW I am 5'6" at 145 lbs. Good luck.
 

·
Moderator
Joined
·
10,978 Posts
When you step on the brake pedal the rod rotates on the pin which is fixed to the pedal.

When the switch rotates, the square end of the rod acts like a cam, depressing the switch.

It is important to have the plastic busing in the area between the switch and the pin. Otherwise there is so much play the switch does not move enough to make a contact.
 

·
Registered
Joined
·
226 Posts
i think i might need to check for a bushing then. In my case the switch works fine, but i have to push the pedal too far for it to engage. Still having trouble picturing how it works. Guess i will have to do the broken back boogie and check it out for myself.
 

·
Registered
Joined
·
11,950 Posts
Great pic there! You should be able to verify the switch activation with an ohmeter. With the probes in the leads and the meter in ohms mode you should see it open/close when acuated
 

·
Registered
Joined
·
6 Posts
Brake lights were working until I changed the turn Signal Switch last night. Good news is that turn signals are now working. This car is a new acquisition so we're finding mysteries. When changing the turn signal switch the old column harness had a jumper from the corner blue wire going to what I think was the dash lights voltage regulator (lt blue/red Wire). Getting rid of that strange jumper may be a clue to the new brake problem. But as of yesterday the brake switch was working, and enough wiring to get all 6 bulbs to shine. Whether that bypass had something to with it I don't know.


This is a early 67. I found an image online of the k11 relay with its wiring. I have not found it under the dash. Reviewing Coaches system troubleshooting I would like to find the K11 and the circuit breakers CB-2 and CB-3. Anyone know where to look. This is also a AC and tilt column car so its crowded and that may of changed where mercury mounted them. I suspect K11 may be MIA.
 

·
Registered
Joined
·
308 Posts
The K11 relay is in the trunk attached to the rubber mat next to the sequential motor.

CB2 is located under the dash right above the accelerator pedal on the windshield wiper bracket. You can test for voltage at the K11 relay on the red wire as power should be always be present.

CB3 is located within the headlamp switch. This then feeds the brake light switch and eventually to the K11 relay on the Green-White wire

Good Luck,

Coach Jack
 

·
Registered
Joined
·
6 Posts
Ok thanks. I have power to the red wire to K11. Then I realized a couple of days ago I removed a crude junper between two green wires leaving k11. Didn't realize it was k11 at the time. Anyway, I jumped the two wires again and the brake lights work with the pedal.... Seems like that jumper should make them stay on all the time. Must be some more rigging somewhere maybe. What I believe is K10 the emergency relay looks to have been mounted somewhere at one time. Do you know where it was mounted. Does it need to be mounted to be grounded correctly? There was a very bad previous owner ground wire connection going to from a K9 wire to the chassis. Looked like it was so bad it wasn't doing anything. But it brings up the question of if or where are grounds in the trunk related to this harness? Thanks a bunch for your help.
 
1 - 20 of 47 Posts
Top