Hydraulic brake light switch question
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From: Southern SC.
Hydraulic brake light switch question
I have no brake lights- just went out driving home. Checked the fuses, grounds, bulbs everything I could think of and no luck. Figured it has to be the switch. Got a new one and still no lights. If I connect the two wires to each other the lights come on just fine. Figured I had the wires backwards - switched them and still no luck. Took switch back thinking it was bad. New one and same results. 6 volt positive ground, drum brakes.all of the other lights work fine even directionals. If I have air in line could that keep a hydraulic switch from working-only thing I can think of. The switch is on the master cylinder between it and rear lines. Any ideas would be appreciated.
Thanks.
Thanks.
Lead Driver
Joined: Jul 2011
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From: Rockingham, VA
If the lights come on when you short the two wires... and the switch is good... the only thing it can be is that the switch is not getting enough brake fluid in to close it.
And it makes absolutely no difference which wire goes to which terminal on the switch. The pressure from applying the brake should close the switch.
I have seen on here others talking about some low pressure switch they really like. But I have a stock m/c and switch and it works fine.
If you suspect air in the line, how do the brakes feel when you push on the pedal?
And it makes absolutely no difference which wire goes to which terminal on the switch. The pressure from applying the brake should close the switch.
I have seen on here others talking about some low pressure switch they really like. But I have a stock m/c and switch and it works fine.
If you suspect air in the line, how do the brakes feel when you push on the pedal?
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From: Southern SC.
Hi Joe-The brakes feel fine - no change from when the lights worked. I will re-bleed them just to be sure. It was sudden that is why I thought the switch. Is there anyway to determine if I have a high pressure switch or low pressure?
More Turbo
Joined: Nov 2004
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From: Marysville, WA
How well do the connectors snap onto the switch? Are they really tight and are they clean? Maybe you just have a bad connection outside the switch. Also is the switch up or down? If the switch is pointing up you could have an air bubble in there.
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From: Southern SC.
The wire actually have screws holding them on. I did replace the two eyes the screws go thru as one wire felt a little loose. The switch is into the side of a connector the real line feeds into so not sure if that makes it up or down. The wires are therefore on the side if it was a clock face they would be a 3 & 9 o'clock.
Lead Driver
Joined: Jul 2011
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From: Rockingham, VA
My switch was bad on the truck when I got it. After I redid the brake lines, hoses, wheel cylinders and M/C, I replaced the switch because the brake lights didn't work.
I just bought one from LMC for $5, but I've read that the big auto parts stores sell them since they're common over many years and makes.
Here's the thread I was talking about with the low pressure switch info.
https://www.ford-trucks.com/forums/1...ht-switch.html
I just bought one from LMC for $5, but I've read that the big auto parts stores sell them since they're common over many years and makes.
Here's the thread I was talking about with the low pressure switch info.
https://www.ford-trucks.com/forums/1...ht-switch.html
Lead Driver
Joined: Jun 2011
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From: Winnipeg, Manitoba
Air will not activate the switch. mount the switch with the connectors facing down (easier to keep air out). I had problems with mine leaking, and will convert to a mechanical switch on the pedal. Good luck.
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From: W. Central FL.
If you have a digital meter.
1 Disconnect wires from switch.
2 Turn meter on and switch to ohm scale. If it has a tone position for the ohm scale, place it in that position.
3 Place one meter lead on each switch terminal.
4 Have someone press brake pedal...meter should sound the tone.
Tone sound=good switch. No sound=bad switch.
If you have an analog meter, it will be a bit more difficult.
1 Disconnect wires from switch.
2 Turn meter on and switch to ohm scale. If it has a tone position for the ohm scale, place it in that position.
3 Place one meter lead on each switch terminal.
4 Have someone press brake pedal...meter should sound the tone.
Tone sound=good switch. No sound=bad switch.
If you have an analog meter, it will be a bit more difficult.
More Turbo
Joined: Nov 2004
Posts: 555
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From: Marysville, WA
Since you have already replaced the switch once I doubt the switch is this issue. It is more likely a bleeding issue in the area of the switch. If you push the brake pedal as hard as you can, can you get the lights to come on? If there is any way for a pocket of air to get stuck in the tube to the switch or switch base it is very likely the cause.
Just because the meter does not beep does not mean the switch is bad, just that the switch is not being activated.
Just because the meter does not beep does not mean the switch is bad, just that the switch is not being activated.
More Turbo
Joined: Nov 2004
Posts: 555
Likes: 5
From: Marysville, WA
If it is digital it should have a tone, it not and you can hook it up to the switch with alligator clamps, you can lay the meter on the ground and watch the needle move from the driver seat if you have no help.
