Skip to main content ↑ ↓
Topic: Brake lights problems (Read 5218 times) previous topic - next topic

Brake lights problems

Hoping someone can offer advise:

The turn signal/dimmer switch in my 86 Mercury Cougar broke so that my turn signals would not work.  I purchased a brand new OEM switch to replace it and once it was installed, my brake lights wouldn't work.  Put the old switch back in and the brake lights work just fine.  What on earth could be causing this and is there any way around it?  I always use my turn signals but, in having to choose, I've had to settle for brake lights :(    HELP!!!!!
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

Brake lights problems

Reply #1 –
something is odd here...

probable faults
-replacement switch is incorrectly manufactured (highly unlikely as these units were fairily cookie cutter universal for several years never changing in design).

-old switch allows brakes to work but one of the internal contacts is open when turn is selected.

-existing bulbs are installed wrong being that just one of the brake / turn bulbs being backwards will cause odd tail lamp behavior

~quick story then you go check..........

once upon a time i had several issues with tail lamps acting up leading me to think a bad turn signal sw on down to flasher being bad or worse a wiring issue somewhere.

The sockets on the rear of these cars that take th dual element bulbs like 1157's become somewhat soft on the interior where the bulb goes in.
This can cause the person putting the bulb in to put the bulb in backwards.  the dual element bulbs have two alignment tits that are offset to prevent backwards installation yet they ***CAN*** be installed backwards and in return you get all kinds of odd results leaving you feeling very frustrated. 

This same issue was kicking my ass and i  good with electrical stuff.  I totally raped the tail end lighting and pulled out every single bulb.  once i was ready, i determined which socket was lefft turn, i placed the turnsignal handle to left turn, inserted my bulb and then learned that the bulbe came super bright and did not flash, yet flipping the bulb 180 deg and re-installing the other way produced a single element to light.  right next to this turn bulb i installed the next bulb and got it right on first try and left turn worked.

I extracted my left turn bulbs and moved these "known good" bulbs to the passanger side.  I selected right turn and installed the two bulbs correctly giving me a right turn result.


Long story short,, if you or anyone has replaced tail lamp bulbs in 87 and down cars, the sockets become soft and could have allowed you to install them backwards.  Just installing on single bulb in the rear will screw everything up.  it will also blow fuse depending on what position your headlamp switch is in.

call if talking through it helps,,, 304 772 3411, scott

Brake lights problems

Reply #2 –
Quote from: jcassity;457775


...
Long story short,, if you or anyone has replaced tail lamp bulbs in 87 and down cars, the sockets become soft and could have allowed you to install them backwards.  Just installing on single bulb in the rear will screw everything up.  it will also blow fuse depending on what position your headlamp switch is in.

call if talking through it helps,,, 304 772 3411, scott

Thanks for all that lengthy explanation jcassity!!  I'm assuming that all my bulbs are in correctly as they work just fine with the old switch and only the brake lights fail with the new switch.  Tail lights work fine with both switches and turn signals work beautifully and automatically with the new switch but I have to hold the turn signal lever either up or down to activate the signals with the old broken switch.  It's driving me NUTS!!
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

Brake lights problems

Reply #3 –
the new switch would have ink stamping on it.

beginning with E4 , e5 or e6

E= 1980's 
number for the year.

some parts are used over several years

post the "E" number up

Brake lights problems

Reply #4 –
in short i gather this......
-old switch caused turn function to not work *only*
-new switch makes turn function work but causes brake lights to not work

i agree,, sketchy

Brake lights problems

Reply #5 –
Quote from: jcassity;457778


post the "E" number up


Looks like this:

E5      LC
I3B302-AA
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

Brake lights problems

Reply #6 –
Quote from: jcassity;457782
in short i gather this......
-old switch caused turn function to not work *only*
-new switch makes turn function work but causes brake lights to not work

i agree,, sketchy

Correct.  Old switch cause turn signals not to work properly because a little metal piece inside it has broken.  Have NO clue why the new one kills my brake lights (not the '3rd' brake light over the package shelf, just the rear bumper ones :(
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

Brake lights problems

Reply #7 –
I found this turn singal switch on RockAuto with the part number you provided and it has it listed as an alternate/OEM part number:

http://www.rockauto.com/en/moreinfo.php?pk=936601&cc=1198537&jsn=384

Is that the one you ordered?  Also, can you find a part number on the original switch?

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

Brake lights problems

Reply #8 –
Quote from: Aerocoupe;457788
I found this turn singal switch on RockAuto with the part number you provided and it has it listed as an alternate/OEM part number:

http://www.rockauto.com/en/moreinfo.php?pk=936601&cc=1198537&jsn=384

Is that the one you ordered?  Also, can you find a part number on the original switch?

The one I have that won't work my brake lights is a brand new OEM Ford part :(      I'll take a look at the one on RockAuto to see if the connectors are the same (I've actually bought a couple that were SUPPOSED to be for my car that had different connector pins and wouldn't work at all :(
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

Brake lights problems

Reply #9 –
this is for 87 year but likely the same... pin out and testing is provided

Brake lights problems

Reply #10 –
Quote from: jcassity;457799
this is for 87 year but likely the same... Pin out and testing is provided

thanks!!!!!!
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

Brake lights problems

Reply #11 –
this switch does come apart if you are good at that kind of stuff.

i had to recently take one apart to fix the handle

Brake lights problems

Reply #12 –
here is a link relating to this switch ,,
in my case i am showing people that for was not correct in saying to replace a broken handle, all you do is yank real hard.

if you do, then the small parts will fall into the switch.

if on your old switch the turn lever easily came out then we may be on to something.... something "fixable" on your old switch.

http://www.foxtbirdcougarforums.com/showthread.php?37543-Solved-*NO*-you-dont-just-yank-real-hard-Turn-Signal-Handle

Brake lights problems

Reply #13 –
Quote from: jcassity;457814
here is a link relating to this switch ,,
in my case i am showing people that for was not correct in saying to replace a broken handle, all you do is yank real hard.

if you do, then the small parts will fall into the switch.

if on your old switch the turn lever easily came out then we may be on to something.... something "fixable" on your old switch.

http://www.foxtbirdcougarforums.com/showthread.php?37543-Solved-*NO*-you-dont-just-yank-real-hard-Turn-Signal-Handle

WOW!!!  Thanks a million for THAT!!  I, of course, have been doing it wrong :(
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

Brake lights problems

Reply #14 –
Quote from: jcassity;457813
this switch does come apart if you are good at that kind of stuff.

i had to recently take one apart to fix the handle

My husband is the electrical guru (he added new relays and wiring to take most of the current off this switch for my headlights and fog lights).  I can now have, low-beams or high-beams with my fogs or just my fogs with no headlights at all.  I sent your diagram to him so he can maybe figure out what that brand new switch is killing my brake lights.  If he can't, I'll just have to buy another one and hope it doesn't do the same thing :(
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.