2001 Mazda 626LX no brake lights

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  #1  
Old 11-26-06, 01:07 PM
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2001 Mazda 626LX no brake lights

2.0L 4cyl with auto trans and no ABS. Drove it home from seller and everything worked including cruise control. A tap on the brake pedal releases the cruise control just like it should. However, when I got home I noticed the brakes lights were not coming on when I depressed the pedal (symptoms are same with or without headlights on or engine running or not). Tail & all other lights work fine with no dash indicators bad or codes in computer.

Four wire brake pedal switch is ok (2 wires for cruise control module deactivate and 2 wires for brake lights). Traced white/green wire from tail lights through pedal switch to cruise control module. Apply 12 volts to module plug and lights come on.

My Haynes manual does not show enough detail to see entire system hookup but it looks like PCM is involved also. So I took a chance & replaced PCM (with same p/n from yard) but no change.

Does anyone know how or if cruise control module is key to brake lights working and if so how? How does the 12v get to the module and then through to the brake light wire. What pin (color wire) is the source for the 12V? Is the PCM actually involved in the circuit? Or better yet, does anyone have a site of the complete wiring they can send me to go see. Any suggestions are appreciated as I don't have that much hair left to pull out. Thanks again. Bill
 
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Old 11-26-06, 03:12 PM
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Your brake lights them selves go from the lights to the brake pedal switch to the fuse. The lights themselves are not tied into your cruise control.
 
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Old 12-06-06, 04:21 AM
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2001 Mazda 626LX no brake lights fix

That is correct that the path is straight through a filter to the switch to the lights and everything on the car worked except for the lights themselves. Wires did split off the circuit to go to the cruise control module but basically it was a straight line.

The fix was I finally noticed that I had 12 volts on the brake line until I plugged in the bulbs then the line went to 0 volts. Although all the other electronics and lights worked fine there was the slightest amount of corrosion on the wire from the battery to the 100amp main fuse.

The fix was to clean off the corrosion and the brake lights started working. That slight amount of resistance caused by the corrosion did not allow enough current to operate the brake lights even though all other lights worked fine. Who wudda thunk? Thanks for your input.
 
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Old 12-06-06, 08:30 AM
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Glad to see you got it fixed! Thanks for posting back with your results!
 
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