Strong GR4 Procedures Manual page 22

Probable Cause
Remove wheel & drum to check
to see if wires are in contact.
Brake magnetic actuator is not
working.
How to Determine
Energize brakes and check with
metal object to see if it is
magnetized.
Current is not present at
electrical connection at rear of
truck.
22
Solution
Replace wires.
Replace bad magnetic actuator.
Check out electrical circuit on
towing vehicle.