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Sep 19, 2015 | 01:30 PM

#16

Mixer man

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From: Bothell & Silverdale, WA

Quote:

Originally Posted by chrislynn5

sorry completely forgot to post pics. They're in the post.
I'm seeing that this truck has one side air brakes? I big compression chamber... And only one side on the rear axle the brake cylinder.

Ok, so that big "compression chamber" is actually a vacuum operated booster for the hydraulic brake system, and that's where the stoplight switch is located. The other "chamber" you see on the rear axle is a vacuum operated shifter for the two speed rear axle. This is remotely operated by the **** on the dashboard.
Hope this helps

Sep 19, 2015 | 01:38 PM

#17

Mixer man

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From: Bothell & Silverdale, WA

Quote:

Originally Posted by chrislynn5

The under side has what appears to be the brake hydraulics and the fuel filter. I see the brakes have power and ground, the fuel filter just ground. This isn't a fuel pump is it? Thank you.

Pic on left shows the master cylinder with the stoplight switch. Pic on the right is an older GM OEM electric fuel pump.

Sep 19, 2015 | 01:57 PM

#18

chrislynn5

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Quote:

Originally Posted by Mixer man

Pic on left shows the master cylinder with the stoplight switch. Pic on the right is an older GM OEM electric fuel pump.

Thank you so much for helping me identify them. So it is a fuel pump, I guess it is grounded on the frame since there is only one wire.

When you say stop light switch? I see that reference in the shop manual, what is the function of this?

I have another topic post asking about the brake hi/lo switch that I think goes with this discussion.

https://www.ford-trucks.com/forums/1...l#post15655489

Sep 19, 2015 | 05:55 PM

#19

Mixer man

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Joined: Sep 2014

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From: Bothell & Silverdale, WA

Quote:

Originally Posted by chrislynn5

Thank you so much for helping me identify them. So it is a fuel pump, I guess it is grounded on the frame since there is only one wire.

When you say stop light switch? I see that reference in the shop manual, what is the function of this? Seriously?

I have another topic post asking about the brake hi/lo switch that I think goes with this discussion.

https://www.ford-trucks.com/forums/1...l#post15655489

The stoplight switch is a normally open (NO) circuit pressure switch that closes the circuit with a rise in pressure. Basically what that translates to is the stoplights light up when you press on the brake pedal.