Service manual

Group 170 Preventive Maintenance

Check Horns

Note: For further information refer to literature in Func-

tion Group 8.

Sound both the air horn (1) and the electrical horn (2).

Each should have a strong, even tone.

Check During Test Driving

Check Clutch Operation

Note: For further information refer to literature in Func-

tion Group 4.

During driving check for smooth operation and engage-

ment when shifting gears. Look for uneven engagement

and/or unusual noise.

Wheel Brake Application and Release

Note: For further information refer to literature in Func-

tion Group 5.

To do the brake test safely, ensure there are no other

vehicles within 300 yards when testing, or perform the

test in a off-road area where there is no trafﬁc. Per-

forming a brake test in trafﬁc may lead to an accident,

and cause personal injury or death.

During the ﬁrst part of driving, check the wheel brakes.

Check for even application and release. Make sure the

vehicle does not pull to the side when the brakes are ap-

plied and that the noise is not generated while braking.

Whether a truck is equipped with ABS brakes or not, the

bobtail proportioning valve will operate as designed, reg-

ulating air brake pressure going to the rear wheel brakes

while not hooked up to a semi-trailer. Rear wheels

should not lock up during moderate braking when in

bobtail mode.

Note: The rear wheels may lock intermittently while driv-

ing unloaded under 30 km/h (20 mph) even when

equipped with ABS brakes. This is normal in unloaded

operation.