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Brake block warning light on top cluster stays on

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VJIAMX View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote VJIAMX Quote  Post ReplyReply Direct Link To This Post Topic: Brake block warning light on top cluster stays on
    Posted: Aug/07/2022 at 4:16pm
Wondering if anyone can tell me causes for this issue when I remove the wire from switch in valve at firewall, the light goes out, brakes seem to work fine no shimmy at pedal??? Thanks
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Heavy 488 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Heavy 488 Quote  Post ReplyReply Direct Link To This Post Posted: Aug/07/2022 at 5:12pm
What does no shimmy at the pedal have to do with the switch telling you there's a pressure differential?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote troutwilly Quote  Post ReplyReply Direct Link To This Post Posted: Aug/07/2022 at 9:44pm
The switch where you disconnected the wire is the pressure differential switch.  It tells you exactly that....there's a pressure difference between the front and rear brakes.  Could be caused by a leak, or have you recently bled the brakes?

You will need to fix a leak first, then remove (un-screw) the switch to let the plunger re-center (the indentation or narrow part of the plunger should be centered below the switch) and re-install the switch.  Brake fluid will not leak out, air will not enter the system when removing and re-installing the switch.
Bill O.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mbwicz Quote  Post ReplyReply Direct Link To This Post Posted: Aug/08/2022 at 6:56am
  Will the plunger re-center by itself with the switch removed?  I'm ready to bleed brakes for the first time on my car (I've gravity fed them).  I have the switch removed and figure that the plunger will shift during the bleeding process.  I wasn't sure how to re-center it if it shifts during bleeding.
  The TSM says to pressure bleed, but I don't have a pressure bleeder.  Any tips to avoid hassles?

Thanks,
Mike
1970 AMX, one step forward, one step back. Both steps cost time and money.
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JGRANTAMX View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JGRANTAMX Quote  Post ReplyReply Direct Link To This Post Posted: Aug/08/2022 at 7:26am
 If the warning light stays on the safety switch contact plunger might be damaged on the end in the switch this can happen if the plunger was not removed before bleeding the brakes, the 70 TSM says to remove the brake safety contact plunger before correcting a brake pressure problem. If you are assembling the system for the first time remove the switch plunger until the system is fully bled and working properly then install the plunger. I have spare plungers because those plungers are easy to damage.

J
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JGRANTAMX Quote  Post ReplyReply Direct Link To This Post Posted: Aug/08/2022 at 7:40am
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