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Discussion Starter · #1 ·
Would appreciate if someone could give me a pointer in diagnosing this problem.
Mazda 626 GF automatic with cruise control.
A bit of history in case it helps:
  • trailer hook was installed professionally many years ago (in case I need to check wiring)
  • air-condition hose was changed / gas was added this month (in case service may have forgotten something)
  • Initially I thought the problem was only in the brakeswitch which I had changed (for a new one) this week.
While changing the switch, I noticed that the rubber button into which the switch pushes
had broken off, I just glued it in place with instant glue.
- Today I tested the cruise control because it is connected to the brake switch. The
light for the cruise control turns on when the cruise
control is turned on but the cruise control does not work - pressing on the lever has no effect.
I disconnected the cruise control wire on the brake switch thinking this may have
some effect, but it made no difference to the brake light problem.

Now for the description of the problem:
With ignition off:
Break light works when I press on the break pedal.

With ignition on/engine off:
Position back light can be turned on/off via light switch and break light works when
break pedal is pressed(both lights are in red part of backlights on car body not trunk lid)

With ignition on, engine on:
Position back light, break light and light in the middle of the trunk lid are on immediately irrespective of whether the
lights are turned on or off and brake pedal has no effect on the break light.
When I turn off the engine, these lights are still on. If I then press the break pedal
several times, there is no effect on the break light but after it is pressed a few more
times, the lights turn off and then the brake light works normally again.

4 Posts
Discussion Starter · #2 ·
OK, I've been able to make progress but have another problem now.
First what I've done as it may help someone else. The rubber button into which the brake switch presses
had broken off i.e. the tab had probably broken off and I suspect that caused the plunger of the switch to be deformed/break and at the
same time the brake lights were constantly on. I glued the button with instant glue as I didn't want to chase around for it
and proceeded to adjust the brake light switch i.e. screwed in so much that the switch was had open circuit so that
the brake lights would be off when the break pedal was not depressed. I fiddled with this but had the
problems described in post #1 i.e. the brake light was always on when the engine was running.
I guess all the while, the main problem was that I couldn't find the right electrical schematic for my car.
Anyway, the next breakthrough came when searching the web I saw that the brake master cylinder
switch was also in the loop together with the tempomat/speed control - I thought there was a defect in that
switch but luckily I first tried lifting the break pedal with my foot while the engine was running and
saw that the brake light switched off. After pumping the brake pedal a bit more and readjusting the
brake switch, I got everything to work properly. I suspect that there is a bit of a combination of adjustment
with the brake switch one needs to perform considering both the brake pedal (getting the switch plunger
adjusted so that the switch is open circuit i.e. break light is off when break pedal is not depressed) and the brake master cylinder oil .

OK, I fixed that by changing the break switch and unfortunately I had to change the car battery - this whole
business had drained it - it was completely flat.

Now I have new problems - maybe it has to do with changing the battery - maybe someone knows
what would cause the radio and touring computer to be off (pressing the radio power button has no effect)
and the touring computer screen is blank ?
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