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Index > Body Exterior > Thread: Brake lights don't work
Thread: Brake lights don't work
captainkrm


1st Gear
Posts: 38
posted June 05, 2011 07:44 PM

Brake lights don't work

I was driving today and my buddy following me told me the brake lights were out. The tail lights come on and the signals work, but nothing when I apply the brake. Fuse is not blown either. Was wondering if anyone had any thoughts as to what the issue could be. I tried unplugging the brake switch and connecting the two wires going to that and nothing happened there either.

       
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captainkrm


1st Gear
Posts: 38
posted June 05, 2011 10:50 PM

trying to diagnose it made it worse. i was testing voltage at the fuses and now i have no signals, idiot lights in the dash or horn. All fuses are good, but i'm worse off/more stumped than before.

       
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sparky


Redlining
Posts: 299
posted June 06, 2011 09:17 PM

At the bottom of the photo gallery page are wiring diagrams. The second page shows lighting circuits. It does not show brake lights but i think the are after the flasher relay. The fuses at the top of the diagram shows a 20 amp fuse that powers up the circuit. I think it is located in the steering column near the ignition switch. Also check the fuses, or fusible links?, located behind the passenger side of bench seat.
____________
'77 REPU
Stock 6-port
T-2 tranny
Weber IDA 48
Alum Flywheel
3rd gen Torsen in rear end.
DLDFIS ignition

       
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captainkrm


1st Gear
Posts: 38
posted June 06, 2011 09:26 PM

i don't recall seeing any links when i pulled the seat out. they are inside the cab? i'll look. is it possible a bad ground at one of the tail lights is causing this? when i was testing the fuses, thats when the dash warning lamps and signal died. could i have popped a relay?

       
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sparky


Redlining
Posts: 299
posted June 06, 2011 11:16 PM

Each tail light has a dedicated ground wire that attaches to the chassis via light assembly. Check this out....

http://www.turborx7.com/images/myrepu/wiringrepu.jpg

Look at grid B-21 on diagram and trace supply power from 20 amp fuse through brake light switch on brake pedal. Zoom on the diagram for more detail. The voltage for the stop lights is passed through the turn signal relay, grid H-19. Green and red striped wire and green and yellow striped wire from relay goues to stop lights. I like wiggle testing wires to check for loose connections. Also, have seen fuse holder connections corrode and not pass voltage from fuses. especialy ones in engine bay.
Hope this helps.
____________
'77 REPU
Stock 6-port
T-2 tranny
Weber IDA 48
Alum Flywheel
3rd gen Torsen in rear end.
DLDFIS ignition

       
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sparky


Redlining
Posts: 299
posted June 06, 2011 11:25 PM

Here is another diagram. easier to read.

http://iwankel.com/manuals/public/REPU%20Wiring,%201974.pdf

Brake switch is in grid O-20.

____________
'77 REPU
Stock 6-port
T-2 tranny
Weber IDA 48
Alum Flywheel
3rd gen Torsen in rear end.
DLDFIS ignition

       
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captainkrm


1st Gear
Posts: 38
posted June 14, 2011 07:07 PM

quote:
Here is another diagram. easier to read.

http://iwankel.com/manuals/public/REPU%20Wiring,%201974.pdf

Brake switch is in grid O-20.



the gray flasher behind the dash is bad. how feasible is finding a replacement?

       
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Jeff20B


Moderator
Posts: 661
posted June 18, 2011 04:50 PM

You can file the contacts so they work again. I've done that for three different older Mazda vehicles. Two REPUs and one Cosmo.
____________
'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7

       
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captainkrm


1st Gear
Posts: 38
posted July 15, 2011 12:14 PM

quote:
You can file the contacts so they work again. I've done that for three different older Mazda vehicles. Two REPUs and one Cosmo.


traced everything back to the turn signal switch being faulty. bypassed that for the brake light switch so that it goes direct to 12v. i have an issue now where the truck will start and run just fine, but when the headlights come on, the lights will dim out and the truck will die a minute after that. i'm betting the battery is toast (just put a new alternator in and that did not solve the problem). thoughts?

       
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roaddancer


Hauling
Posts: 127
posted July 16, 2011 12:30 PM

If it is still the factory fuse block it may be resistance there, or even old fuses that look ok but are not.
And all DC circuits are subject to strange behavior caused by poor grounding, so check that everywhere.
Your bypass to get brake lights may have compromised the voltage regulator somehow causing light fading... If the truck starts and runs and the alternator is good, it probably isn't the battery causing it to dim, as the alternator will put out enough voltage to light everything. Check the battery ground cable on both ends just in case.
Check to see if you hooked up something into the circuit that bypasses the coil resister causing it to stay hot after start. That might do something to your voltage. If that is the case it will toast your points if you still have those.
I would start out just wiggling ground wires. So many ghosts from that.
____________
formerly
rx2/3/4/cosmo,repu,94 rx7,

       
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