low brake switch
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I believe on most of our trucks it is called a Brake Proportioning Valve. On my '77 it is near frame rail, drivers side, under cab. I think its called the pressure switch that screws into this valve and signals light on dash.
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Josh
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My 79 is located in the same place as yours.
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From: 40min from Charlotte NPD.
Mine is under the cab by the frame rail as well, "1977 F100 302 2WD Man-Steering Man-Brakes. I thought of moving mine up near or next to the master cylinder but was unsure of the purpose of the lengths of coiled steel line running to the valve. Could there be a problem if the lines from the MC to the prop valve were only 6"-1' long?
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Mine is a 2wd and is not above the steering box. It's down somewhat under the cab mounted on a crossmember
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From: Simi Valley, CA
C8AZ2B264A .. Low Brake Fluid Warning Lamp Switch / Available from Ford / Threads into the brass Brake Differential Proportioning Valve.
This valve could be located in three possible locations:
1) Below the master cylinder adjacent to the steering gearbox.
2) Bolted to the outside of the left frame rail directly behind the left front wheel.
3) Bolted to the outside of the left frame rail to the rear of the steering gearbox.
The low brake fluid switch is plastic, develops cracks in the threads, causing fluid to seep out.
When that occurs, the low brake fluid warning light on the dash comes on...and stays on.
C8AZ2B264A fits: 1968/79 F100/350 / 1968/79 Bronco / All 1968/69 Passenger Cars / 1969/79 Econoline.
MSRP: $33.64 // FTE sponsor: y2kfordparts.com price: $18.17.
This valve could be located in three possible locations:
1) Below the master cylinder adjacent to the steering gearbox.
2) Bolted to the outside of the left frame rail directly behind the left front wheel.
3) Bolted to the outside of the left frame rail to the rear of the steering gearbox.
The low brake fluid switch is plastic, develops cracks in the threads, causing fluid to seep out.
When that occurs, the low brake fluid warning light on the dash comes on...and stays on.
C8AZ2B264A fits: 1968/79 F100/350 / 1968/79 Bronco / All 1968/69 Passenger Cars / 1969/79 Econoline.
MSRP: $33.64 // FTE sponsor: y2kfordparts.com price: $18.17.
Ford Parts Specialist
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From: Simi Valley, CA
The proportioning valves are not the same.
It depends on the year, series, 2WD or 4WD and in some cases, the GVW.
The OP has a 1978 F100.
D5TZ2B257B .. Brake Differential Proportioning Valve / Marked: D5TA-2B524-FA or FB.
Fits: 1975/79 F100/150 2WD/4WD with disc brakes / 1975/79 F250 2WD with a GVW of 6200 lbs. (single piston calipers).
Fits: 1976/79 F250 4WD / 1979 F350 4WD.
Fits: 1976/77 U100 with disc brakes / 1978/79 U150 (U = Bronco).
Fits: 1975/79 E100/150 (E= Econoline).
There are FIVE other valves listed for the rest of the 1973/79 F100/350's. Two of these same valves fit 1975/79 E250/350's.
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