2002 Brake light doesn't work

Joined
Jul 23, 2022
Thunderbird Year
2002
Hi Guys!๐Ÿ‘
Anders from Sweden here... Nice forum!! Lots of use already..
Bought a 2002 Tbird as a modern complement to my Factory Mustang GT Convertible 66 and liking it a lot.
Problem thou - got no rear brake lights or high brake light
Everything else are working fine (instrument lights, front, blinkers and back light)
Done sofar:
New brake switch
Bulbs
All fuses checked 35 passenger + from memory 5 7 8 9.. at the back
Measured: no 12V on brake switch contact by the pedal
No 12V out from fuse 35 by the passengers feet
Any Ideas where to go next
doug 7740 ?? :)


Thanks in advance
Have a good day

Best Regards Anders
 
Joined
Oct 11, 2018
Thunderbird Year
2002
Hi Guys!๐Ÿ‘
Anders from Sweden here... Nice forum!! Lots of use already..
Bought a 2002 Tbird as a modern complement to my Factory Mustang GT Convertible 66 and liking it a lot.
Problem thou - got no rear brake lights or high brake light
Everything else are working fine (instrument lights, front, blinkers and back light)
Done sofar:
New brake switch
Bulbs
All fuses checked 35 passenger + from memory 5 7 8 9.. at the back
Measured: no 12V on brake switch contact by the pedal
No 12V out from fuse 35 by the passengers feet
Any Ideas where to go next
doug 7740 ?? :)


Thanks in advance
Have a good day

Best Regards Anders
The wiring diagram shows fuse 35 should be hot at all times. I see you "checked" 35, does it have power? Diagram also shows straight connection to brake pedal switch. Switch then goes direct to REM (rear electronics module). That module actually controls the rear lights. If you truly have no 12v at pedal switch, check for power at 35, if power there then either a bad fuse or a break in wiring between 35 and pedal switch. Is there only one switch on pedal? What about a switch for cruise control, although maybe the REM uses brake switch signal to also disengage cruise.

Greg Lentz
 
Joined
Oct 11, 2018
Thunderbird Year
2002
Hi Greg!
Nice to hear from you.:)
NO 12v at brake switch or No 35 fuse..(switch replaced)
Cruise works just fine like everything else..
Hmm strange fault that puzzles me

Best Regards
//Anders-
Just to confirm, no voltage at either terminal of fuse 35?. One of those terminals is supposed to be hot at all times (brake lights will come on even when care is off). If no voltage at the fuse then something is wrong further upstream (between battery and fuse 35).

Greg
 

doug7740

Active Member
Joined
Dec 29, 2014
Thunderbird Year
1955
Hi Guys!๐Ÿ‘
Anders from Sweden here... Nice forum!! Lots of use already..
Bought a 2002 Tbird as a modern complement to my Factory Mustang GT Convertible 66 and liking it a lot.
Problem thou - got no rear brake lights or high brake light
Everything else are working fine (instrument lights, front, blinkers and back light)
Done sofar:
New brake switch
Bulbs
All fuses checked 35 passenger + from memory 5 7 8 9.. at the back
Measured: no 12V on brake switch contact by the pedal
No 12V out from fuse 35 by the passengers feet
Any Ideas where to go next
doug 7740 ?? :)


Thanks in advance
Have a good day

Best Regards Anders

Anders,

You mentioned that there was no voltage coming out from fuse 35 and that you checked fuse 35 and it was good. Since fuse 35 is not defective, did you check to see if you have voltage going in fuse 35?

doug7740
1955 Thunderbird Blue

Untitled.jpg
 
Joined
Jul 23, 2022
Thunderbird Year
2002
Hello Greg: No 12V at fuse 35.. measured just with ignition on and two pins from the voltmeter over the no 35 two conection pins.

Hi Doug!:) Nice to hear from you too.
and Thanks for answering!
....did you check to see if you have voltage going in fuse 35? Can you explain for me how to check: "going in" fuse 35
I have checked over no 35 pins and have no voltage anywhere.
Must check again towards ground.....(i may have made a mistake)

I'll keep you guys posted. Will continue tomorrow.

Best Regards
//Anders
 
Joined
Oct 11, 2018
Thunderbird Year
2002
Hello Greg: No 12V at fuse 35.. measured just with ignition on and two pins from the voltmeter over the no 35 two conection pins.

Hi Doug!:) Nice to hear from you too.
and Thanks for answering!
....did you check to see if you have voltage going in fuse 35? Can you explain for me how to check: "going in" fuse 35
I have checked over no 35 pins and have no voltage anywhere.
Must check again towards ground.....(i may have made a mistake)

I'll keep you guys posted. Will continue tomorrow.

Best Regards
//Anders
MrMustang66,

It sounds like you are measuring wrong for the fuse terminals and you have likely already determined that. Your ground wire from tester must go to ground, not to one of the fuse holder pins. Neither of those pins is ground and only one will be hot.

Greg
 
Joined
Oct 11, 2018
Thunderbird Year
2002
MrMustang66,

It sounds like you are measuring wrong for the fuse terminals and you have likely already determined that. Your ground wire from tester must go to ground, not to one of the fuse holder pins. Neither of those pins is ground and only one will be hot.

Greg
P.S. The same is true for the brake switch. One of your tester leads must go to ground, not to the other pin on the brake switch.
 
Joined
Jul 23, 2022
Thunderbird Year
2002
Hi!
Progress.... +12V on the fuse no 35... Check/Ok...
but no 12V on/by the contact (new measuring with a better ground)
The fault must be in the cable to the contact..
Time is also running out for me.. It would be so neat if I could clear this fault before the winter. The car will go into storage in a couple of weeks in a barn.
So ongoing:)
Thanks for your answers sofar.

Regards
Anders
 

doug7740

Active Member
Joined
Dec 29, 2014
Thunderbird Year
1955
Anders,

If I understand correctly, you have 12 volts going in and out of fuse 35, but there is no voltage at terminal #1 of the Brake Pedal Position Switch. If that is the case the orange/green wire that runs from connector C270B, terminal 2 of the Central Junction Box to terminal #1 the Brake Pedal Position Switch could have an open circuit, but you have to check the Central Junction Box first.

There are five connectors on the Central Junction Box, make sure there is 12 volts coming out of terminal #2 of connector C270B before you start looking for an open circuit in the orange/green wire that runs to the Brake Pedal Position Switch.

doug7740
1955 Thunderbird Blue

CJB.jpg
 
Joined
Jul 23, 2022
Thunderbird Year
2002
Hi Doug!๐Ÿ™‚
Thanks again for your explanation .. I really appreciate it.
But just to complicate things the bird is rewired when imported to Sweden.
US function: Normal/ Blinker/ Stop Light in the big red lamps and underneath back up lamps.
Sweden way : Normal/ Brake light in the big red lamps. Backup lamps now serves as Blinkers ( bulbs changed to amber/orange light)
I can see that someone has tampered with the cables high up above the brake pedal switch. (car imported 2007)
Which means that the colors of the cables may no longer match.. Im not sure..
The working position is not the best under the instrument panel...โ˜น๏ธ
To be continued.

Best Regards
Anders
 
Joined
Jul 23, 2022
Thunderbird Year
2002
Let there be light!! :).....Finally got the lights working again..
(With the help of a good friend)
It was a two step rocket
1. the brake light switch was faulty. Caught that fault early on.
2. Turned out it was a loose cable 12V+ that have become loose at the rear junction box due to the european brake light conversion (See the above explanation)
Thanks doug7740 and greg132 for the schematics and good hints

Best Regards Anders
 
Joined
Jul 15, 2022
Thunderbird Year
1960
Hi Guys!๐Ÿ‘
Anders from Sweden here... Nice forum!! Lots of use already..
Bought a 2002 Tbird as a modern complement to my Factory Mustang GT Convertible 66 and liking it a lot.
Problem thou - got no rear brake lights or high brake light
Everything else are working fine (instrument lights, front, blinkers and back light)
Done sofar:
New brake switch
Bulbs
All fuses checked 35 passenger + from memory 5 7 8 9.. at the back
Measured: no 12V on brake switch contact by the pedal
No 12V out from fuse 35 by the passengers feet
Any Ideas where to go next
doug 7740 ?? :)


Thanks in advance
Have a good day

Best Regards Anders
In electrical problems a high precent of the time the ground is the problem find allgrounds take take them off alittle dremmel brush works well. Since brake lights work at higher amps put new bulbs in make sure the socket contacts are in good shape do a tester light test from good positive to ground also viscera. Also while some one is mashing brake. We make sets of jumper wires out of cheep 20 ft extention cords and alligator clips. Check continuity!! I have seen fuse pannels worn out in the back side gets 12 volts but too many amps has shorted out. Bad grounds will pull alots of resistance and burn a positive wire.
 
Joined
Jul 15, 2022
Thunderbird Year
1960
In electrical problems a high precent of the time the ground is the problem find allgrounds take take them off alittle dremmel brush works well. Since brake lights work at higher amps put new bulbs in make sure the socket contacts are in good shape do a tester light test from good positive to ground also viscera. Also while some one is mashing brake. We make sets of jumper wires out of cheep 20 ft extention cords and alligator clips. Check continuity!! I have seen fuse pannels worn out in the back side gets 12 volts but too many amps has shorted out. Bad grounds will pull alots of resistance and burn a positive wire.
Sorry I forgot to say put the grounds back on
Make sure they are really secure.
 
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