Automatic Lubrication System - Section 42 7/11 OM4213
Page 42-12
SYSTEM TROUBLESHOOTING CHART
NOTE: If the following procedures do not correct the problem, contact a factory authorized service center.
TROUBLE POSSIBLE CAUSES SUGGESTED CORRECTIVE ACTION
Pump Does Not Operate
Lube system not grounded.
Electrical power loss.
Timer malfunction.
Solenoid valve malfunctioning.
Relay malfunctioning.
Motor or pump malfunction.
Correct grounding connections to pump
assembly and truck chassis.
Locate cause of power loss and repair.
24 VDC power required. Ensure key
switch is ON.
Replace timer assembly.
Replace the solenoid valve assembly.
Replace relay.
Repair or replace motor and/or pump
assembly. (Refer to shop manual for
rebuild instructions.)
NOTE: On initial startup of the lube system, the timing capacitor will not contain a
charge, therefore the first timing cycle will be about double in length compared to
the normal interval. Subsequent timer cycles should be as specified.
Pump Will Not Prime
Low lubricant supply. Dirt in reservoir, pump inlet clogged, filter
clogged.
Pump Will Not Build
Pressure
Air trapped in lubricant supply line.
Lubricant supply line leaking.
Vent valve leaking.
Pump is worn or scored.
Prime system to remove trapped air.
Check lines and connections to repair
leakage.
Clean or replace vent valve.
Repair or replace pump assembly. (Refer
to shop manual for rebuild instructions.)
Injector Indicator Stem
Does Not Operate
NOTE: Normally, during operation, the injector indicator stem will move into the
body of the injector when pressure builds properly. When the system vents
(pressure release) the indicator stem will again move out into the adjusting yoke.
Malfunctioning injector - usually
indicated by the pump building
pressure and then venting.
All injectors inoperative - pump
build up not sufficient to cycle
injectors.
Replace individual injector assembly.
Service and/or replace pump assembly.
(Refer to shop manual for rebuild
instructions.)
Pressure Gauge Does Not
Register Pressure
(pressure gauge not
included with pump)
No system pressure to the pump
motor.
No 24 VDC signal at pump
solenoid.
Pressure reducing valve set too low.
24V Relay (RB7K8 or RB7K5) may
be defective.
Check hydraulic hose from steering
system.
Determine problem in 24 VDC electric
system.
Refer to “Pressure Control Valve
Adjustment”.
Replace relay.
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