TROUBLESHOOTING
Page 113
MACK POWERLEASH™ SOLENOID SPECIFICATIONS
INTERMITTENT BRAKING
Inspect all wiring for loose connections and all
switches for proper adjustment.
POOR PERFORMANCE
Connect a volt/ohmmeter (multimeter) to the
electrical connector on the valve cover/spacer.
Verify that a steady voltage signal is present
when the engine brake is active. If not, check for
loose connections or faulty switches. Repeat for
all valve cover/spacer terminals.
MACK PowerLeash™ Checks
(Hydraulic/Mechanical)
Remove the covers to begin inspecting the brake
components, including housings and attendant
hardware.
GENERAL INSPECTION AND ADJUSTMENT
VERIFICATION
1. Inspect for missing or loose mounting
bracket-to-rocker shaft bolts. The center and
rear rocker shaft mounting brackets contain
retaining bolts which intersect with the
rocker shaft “control” oil gallery. If the center
or rear rocker mounting bracket-to-rocker
shaft bolts are loose or missing, a loss of
control oil pressure and loss of brake
function will occur.
2. Visually inspect the rocker shaft, exhaust
rocker arms, hydraulic actuators, solenoid
valve, etc., for obvious signs of damage or
missing components. Repair or replace as
necessary.
3. Check solenoid operation. The solenoid
used with the MACK PowerLeash™ has a
0.200 inch diameter hole in the top that
provides a means of troubleshooting
solenoid operation. To check solenoid
operation, insert a pin (having a diameter
less than 0.200 inch) into the hole, then
activate the engine brake. The pin should
rise approximately 0.100 inch (2.54 mm)
when the solenoid turns ON.
4. Check the valve yoke clearance, brake lash
and valve lash adjustments. Readjust if
necessary.
12-Volt Solenoid (P/N 805GC54)
Resistance:
— 9.62 to 10.75 ohms (cold)
— 11.8 to 14.3 ohms (hot)
Current Draw:
— 0.84 to 1.66 amps (cold)
— 0.63 to 1.36 amps (hot)
Pull In Voltage:
— 9 volts DC minimum
5-111.bk Page 113 Monday, July 10, 2006 2:26 PM
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