 Brain Trust Help needed on Parking Brake Light, Parking Brake Light Always on...... |
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| Gatornapper |
 Jul 4 2025, 07:40 PM
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#1
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Senior Member  Group: Members Posts: 1,283 Joined: 22-September 17 From: Woods west of Richmond, VA Member No.: 21,449 Region Association: South East States 
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Once again need the help of the great 914 Brain Trust here........
My Parking Brake Light stays on all the time. The switch is fairly new and it is functioning properly. Disconnecting the brown (ground) wire to the switch, it has no continuity or resistance to ground. So it is not "grounded out" somewhere. I see in my great 914 electrical schematic of the ground circuit for the switch and light that there are two diodes in the circuit. I am guessing that one of them failed. Can anyone tell me where these two diodes are located? Or where else the problem might be? As always, TIA, GN |
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| 914 |
Jul 11 2025, 07:23 AM
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#2
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Senior Member Group: Members Posts: 460 Joined: 26-December 02 Member No.: 19 Region Association: Southern California
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Is there a reset button/Switch on the Master Cyl?
914/Alan |
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| Jamie |
Jul 11 2025, 08:55 AM
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#3
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Senior Member Group: Members Posts: 1,151 Joined: 13-October 04 From: Georgetown,KY Member No.: 2,939 Region Association: South East States
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QUOTE(914 @ Jul 11 2025, 05:23 AM)  Is there a reset button/Switch on the Master Cyl? 914/Alan I've tried that reset switch multiple times without resulting in ending the flashing. Will next remove the wire from the MC when I can next get the car up on the lift. |
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| Gatornapper |
Jul 14 2025, 03:14 PM
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#4
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Senior Member Group: Members Posts: 1,283 Joined: 22-September 17 From: Woods west of Richmond, VA Member No.: 21,449 Region Association: South East States
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I'll do the same. Lift presently occupied preparing my sweet 944 S for buyer next week. After acquiring my Concours 951 last September, my beloved wife thinks no man needs two nice 944's, and I actually agree.
What in the world does this wire to the MC do? Make sure there is fluid in MC? Why is there a reset on it? GN QUOTE(Jamie @ Jul 11 2025, 08:55 AM) QUOTE(914 @ Jul 11 2025, 05:23 AM) Is there a reset button/Switch on the Master Cyl? 914/Alan I've tried that reset switch multiple times without resulting in ending the flashing. Will next remove the wire from the MC when I can next get the car up on the lift. |
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| Superhawk996 |
Jul 14 2025, 05:47 PM
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#5
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914 Guru Group: Members Posts: 7,360 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch
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QUOTE(Gatornapper @ Jul 14 2025, 05:14 PM) What in the world does this wire to the MC do? Make sure there is fluid in MC? Why is there a reset on it? The master cylinder switch senses a loss of pressure in either of the two braking circuits. If there is a pressure differential across the sensing piston inside the master cylinder, it trips the latching switch. This will occur during brake bleeding - thus the reset switch. If you haven’t bled the brakes and this circuit is being tripped, it is a serious issue and shouldn’t be ignored. |
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| Gatornapper |
Jul 20 2025, 01:56 PM
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#6
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Senior Member Group: Members Posts: 1,283 Joined: 22-September 17 From: Woods west of Richmond, VA Member No.: 21,449 Region Association: South East States
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SH -
Have electrical schematics for '87 944? GN QUOTE(Superhawk996 @ Jul 14 2025, 05:47 PM) QUOTE(Gatornapper @ Jul 14 2025, 05:14 PM) What in the world does this wire to the MC do? Make sure there is fluid in MC? Why is there a reset on it? The master cylinder switch senses a loss of pressure in either of the two braking circuits. If there is a pressure differential across the sensing piston inside the master cylinder, it trips the latching switch. This will occur during brake bleeding - thus the reset switch. If you haven’t bled the brakes and this circuit is being tripped, it is a serious issue and shouldn’t be ignored. |
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| Superhawk996 |
Jul 20 2025, 02:38 PM
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#7
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914 Guru Group: Members Posts: 7,360 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch
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QUOTE(Gatornapper @ Jul 20 2025, 03:56 PM) SH - Have electrical schematics for '87 944? GN Appear to be available online in a couple places. I haven’t looked for 87’ but you should find some general info that you’re looking for to at least get you going. https://www.pelicanparts.com/944/electrical...KXI-hEDyEc0bAkW |
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Posts in this topic
Gatornapper Brain Trust Help needed on Parking Brake Light Jul 4 2025, 07:40 PM
jim_hoyland MC ?
I just went through this… :) Jul 4 2025, 08:41 PM
Jamie
MC ?
I just went through this… :)
I'm also... Jul 5 2025, 09:03 AM Superhawk996
I'm also trying to troubleshoot the flashing... Jul 5 2025, 12:25 PM Literati914 @Gatornapper - if you pull the combo gauge, you... Jul 5 2025, 10:01 AM Gatornapper Ah yes! On my schematic it does look like one... Jul 5 2025, 10:47 AM BillC
What is "MC"?
"MC" is short ... Jul 5 2025, 11:05 AM Literati914
What is "MC"?
"MC" is short... Jul 5 2025, 12:10 PM Superhawk996 Simplified schematic from Spoke Jul 5 2025, 12:23 PM Gatornapper Ah, yes.
Thank you SH for the schematic.
NO diod... Jul 9 2025, 05:44 AM Spoke For the MC warning switch, you can disconnect the ... Jul 9 2025, 06:36 AM Gatornapper Thanks Spoke.
Light still flashes with brake wire... Jul 11 2025, 06:41 AM Cairo94507 On my MC there is- ATE. :beer2: Jul 11 2025, 08:06 AM Gatornapper Change of subject as I have no where else to go: ... Jul 17 2025, 06:07 AM Literati914 I have the same issue with the stupid flashing lig... Jul 17 2025, 12:35 PM Gatornapper Thanks.
Gonna unplug mine - if there is one. My ... Jul 17 2025, 07:28 PM Superhawk996
No need for warning light.
:blink: :headbang... Jul 17 2025, 10:18 PM Superhawk996
I’d say ‘don’t be surprised if there is n... Jul 17 2025, 10:14 PM Literati914
I’d say ‘don’t be surprised if there is ... Jul 21 2025, 08:12 AM Superhawk996
[quote name='Literati914' post='3215412' date='J... Jul 21 2025, 10:13 AM Literati914
.. [i]They all have some type of a square plastic... Jul 21 2025, 04:01 PM Superhawk996
Were there EARLY two-pole switches with manual b... Jul 21 2025, 04:27 PM Lucky9146 Finding this thread helpful in diagnosing my own s... Jul 21 2025, 08:58 PM Gatornapper Finally got car on lift to find that there was no ... Sep 2 2025, 07:58 AM Spoke
Finally got car on lift to find that there was no... Sep 2 2025, 08:54 AM |
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