Height Sensing Proportioning Valve - Service Procedure

Article No. 85-21-14

BRAKE - VEHICLE HEIGHT SENSING PROPORTIONING VALVE SERVICE PROCEDURE

LIGHT TRUCK 1985-86 F & E-250/350

All F & E-250/350 vehicies built after May 1, 1985 will be equipped with a brake height sensing valve.

Figure 16 - Sensing Proportioning Valve/Service Procedure:

The valve is located on the number five crossmember and is activated through a linkage system that is connected to the axle housing cover of the rear axle assembly. See Figure 16. The following service procedure is recommended for removing and installing the valve assembly.
1. Raise vehicle on hoist and allow the rear suspension and rear axle to hang in full rebound position. (Rear shock absorbers, if so equipped, must be connected to the rear axle.)

2. Remove both rear wheels and tires.
3. Remove linkage assembly (2C193) from the valve (2B547).

4. Remove the brake hose (2282).

5. Remove valve (2B547) from mounting bracket (2B526) and replace with new valve (2B547).

6. Position and attach the sensing valve (2B547) to mounting bracket (2B526) with two bolts. Torque bolts to 14-22 ft.lbs.

7. Connect linkage assembly (2C193) to the sensing valve shaft. Squeeze the plastic bushing of the link assembly onto the serrated section of the valve shaft using large groove-joint type pliers.

8. Install nut (379930) securing link assembly to valve shaft. Torque nut to 8-10 ft.lbs.

9. Install rear brake hose assembly (2282) to the sensing valve (2B547) with the existing bolt (385116) and two new washers (388949). Torque bolt to 17-25 ft.lbs.

10. Bleed brake system and correct any leakage.

11. Install wheels and tires.

12. Lower vehicle.

13. Road test to confirm repair.

NOTE: The valve will automatically become operational when the vehicle's suspension is in the "curb condition".

When servicing other rear suspension components (axle assembly, rear springs, fuel tank, etc.), remove the two nuts attaching the sensing valve linkage (2C193)to the rear axle cover plate. This will eliminate the need to replace the brake valve. If the linkage assembly is disconnected from the height sensing valve, a new sensing valve must also be installed.

NOTE: Any change to the vehicle rear suspension which will alter "curb" ride height (e.g. increased capacity leaf springs, addition of spacers, etc.) may change the function of the height sensing valve and alter the system braking performance.

The new sensing valve assembly will have the shaft preset and secured internally. If the valve shaft of the valve turns freely - DO NOT USE. The height/load sensing brake proporting valve (2B547) is not to be repaired or disassembled. It must be replaced as a complete assembly. If the linkage assembly (2C193) is damaged or broken and requires replacement, a new sensing valve must also be installed.
OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: Reimbursable within the provisions of the Warranty and Policy Manual.
OPERATION: SP2547B85
TIME: 1.6 Hrs. DLR. CODING: Basic Part No. 2B547 - Code: 42
NOTE: Reimbursable under warranty only if the height sensing valve is defective. Height sensing valves replaced because of damaged or broken linkage assembly (2C193) are not reimbursable under warranty.