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Discussion Starter · #1 ·
Easy Question

OK Guys, I'm going to show just how new I am to the GT.:cool:

What is the red annunciator light on the instrument panel? Mine stays on all the time. I'm guessing it is a brake system warning light. If so what do I need to do to put it out? I just rebuilt the front calipers but I haven't looked at the back brakes yet. Thanks.
Gregg
 

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Discussion Starter · #3 ·
Oh, OK, I'll look at that. I've used the emergency lever many times but perhaps the switch is misrigged. Thanks
 

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Discussion Starter · #4 ·
Well, I checked the e handle and don't find anything electrical associated with it. What I did find was the wire providing the power to this light is attached a pressure switch on the master cylinder. Now, the brakes seem to work pretty well, does this mean I need to bleed them or is it an indication that the master cylinder is failing?
 

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The red light on the dash is an indication of a brake system pressure imbalance, and indicates that the master cylinder internal assembly is not "neutral" between the front and rear ports. The switch on the MC is actually just a "normally open" switch that has a pin that rests between the front and rear MC plungers. When the plunger is pushed unevenly from front to rear or vice versa, the pin is pushed into the switch which closes the circuit.

This can be caused by losing pressure on one end of the brake system versus the other (front to rear), such as when bleeding only one end. Or it can be caused by a failure of one of the set of internal MC seals. Try bleeding the brakes. Sometimes it is necessary to bleed the master cylinder as well as the lines.

And it was only automatics that had an emergency brake indicator switch, which caused the red indicator to light up. But all models have a rocker switch on the lower dash console that, when either end is pushed, both the rocker and dash light should glow.

HTH
 

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Discussion Starter · #6 ·
Thanks kwilford,:D

I'll give that a try tonight, appreciate the help guys.
 

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Washout said:
Thanks kwilford,:D

I'll give that a try tonight, appreciate the help guys.

If you get this fixed let us know.
I've been dealing with the same situation for the last 4 months and the light still "on" ... after many (lost count) bleeding attempts!

At this point, in my case, I suspect a "faulty" MC (which I got from NAPA) .

Good luck!
 

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likengtj said:
If you get this fixed let us know.
I've been dealing with the same situation for the last 4 months and the light still "on" ... after many (lost count) bleeding attempts!

At this point, in my case, I suspect a "faulty" MC (which I got from NAPA) .

Good luck!
It may not be your MC... It might be your rubber brake hoses.

I also had the Red Light after I changed out the MC...

Changed all three hoses, bled the system & voila, No Red Dash light

Hope this works for you too.
Marc
 

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Discussion Starter · #9 ·
Well, I tried bleeding the brakes again and that did not extinguish the red light. As time permits this weekend I'll try again. I've already changed the two front brake lines and the rear brakes seem to work fine. I may try removing and cleaning the switch from the MC and see if that resets the light. I'll let you know.
 

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On my kadette the red light is the alternator indicator, I do not know if this is the same for all cars. but you might want to check your alternator.
 

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caldwell-kid said:
On my kadette the red light is the alternator indicator, I do not know if this is the same for all cars. but you might want to check your alternator.
Not the case on a GT ... the red light indicator is for the brakes.

BTW, I did try cleaning/checking the switch unit itself and it works as designed.

Did you rebuild the original MC or bought one (rebuilt) from NAPA?
 

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likengtj said:
Not the case on a GT ... the red light indicator is for the brakes.

BTW, I did try cleaning/checking the switch unit itself and it works as designed.

Did you rebuild the original MC or bought one (rebuilt) from NAPA?
I bought a rebuilt MC from OGTS.

If you haven't done this already, It may be the rubber brake hoses. I was told not to change only 1 or 2 hoses, but to always change all 3 due to the different pressure on the insides of an old hose vs a new hose.

It did the trick on mine & my brakes feel like new (cause they are!)
Marc
 

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Marc said:
I bought a rebuilt MC from OGTS.

If you haven't done this already, It may be the rubber brake hoses. I was told not to change only 1 or 2 hoses, but to always change all 3 due to the different pressure on the insides of an old hose vs a new hose.

It did the trick on mine & my brakes feel like new (cause they are!)
Marc
I replaced all 3 rubber hoses + new lines, still have the light on!
My MC was from NAPA, shoud've stayed with OGTS :mad:
 

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Discussion Starter · #14 ·
UPDATE on my brake warning annunciator light. I rebuilt the master cylinder today and that cured the light. The plungers in the switch circuit were gummed up and full of 30 years of crud. It might be your master cylinder afterall likengtj.
 

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GT master cylinder

i got in my gt today to drive it to the paint shop on the way that red light came on for the brake system brakes still felt fine drove to the paintshop but was to late they were already closed so i drove it back home and checked that wire on the master cylinder it wus still connected so i disconnected it and then the ligth wus out, so i assume something went wrong inside master cylinder i rebuilt less then 20 miles ago or so and havent had any problems till now, any ideas on what else to do or to check, any help will be appreciated.
 

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If you have not check the brake fluid level, I'd say that your m/c is due to be rebuilt or replaced.
 

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I merged these threads
 

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well i have jus rebuilt the master cylinder less then about 20 or 30 miles agoand the light jus came on. is it safe to say if the brkaes still work and feel fine to jus ignore the light??
 

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red light on GT dash for brakes

Just found out yesterday that on the 72 and 73 GTs, the light does come on for the park brake even if they are not automatics. My 72, which has a bild date of 7-71 does not work that way but Marcs 72 has a mid 72 build date does and so does Ricks pristine 73.
 

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Jim, you're correct . Here is the Opel Tech Bulletin to prove it. It even gives the exact serial # when the change occured. I have about 200 different Technical & Sevice Bulletins from 68-75 and even some for the earlier models. There is lots of great info on when changes occured & for corrections to the service manuals.


Tom C.
 

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