Half/Pack
®
Issued April 2018
Compressed Natural Gas (CNG) Option
Copyright 2018, Heil Environmental
Printed in the U.S.A.
Compressed Natural Gas (CNG) Option
194
CNG FUEL MODULE TROUBLESHOOTING (CONTINUED)
The following table lists possible problems, along with causes, corrections, and results.
CORRECTIVE/DIAGNOSTIC
ACTIONS
Vehicle's starter will not
operate.
Interrupt door switch signal
is not being properly
recognized by the vehicle.
Disconnect the 12-pin electrical
connector at the rear of the fuel
module. Use an ohm meter or
continuity tester across pins
(GRN) and 10 (YEL) of the fuel
module side of the connector
(female connector).
Press and release the fuel
module interrupt door switch.
When the switch is depressed,
there should be continuity
between pins 9 (GRN) and 10
(YEL). Continuity should be lost
when the switch is released.
If operation of the door
switch makes and breaks
continuity as described,
and the starter will not
operate, there is most
likely a problem in the
vehicle's wiring.
If the operation of the door
switch does NOT make or
break continuity as
described, there is most
likely a wiring problem in
the fuel module.
If the problem cannot be
resolved, call 866-310-
4345 for technical
assistance.
Vehicle's starter operates
but the vehicle does not
run.
Fuel is not making it
through the fuel module to
the engine.
*The manual valve on the front
of the fuel module should be
set to "On".
*The fuel module high pressure
gauge should read above 5000
psi. Disconnect the 12-pin
electrical connector at the rear
of the fuel module. Use a DC
voltmeter across pins 8 (BLU)
and 9 (GRN) of the vehicle side
of the connector (male
connector). The voltage should
read:
Ignition switch "Off" 0 vdc.
Ignition switch "Run" 12 vdc.
Ignition switch "Start" 12 vdc.
*Reconnect the 12-pin
electrical connector at the rear
of the fuel module. Have an
assistant repeatedly cycle the
ignition switch between "Off"
and "Run" while listening for
the "click" of the fuel solenoid
being actuated near the
maintenance door.
*If the voltage does NOT
change as described, the
problem is most likely
located in the vehicle's
electrical signal that
actuates the fuel solenoid.
*If the voltage changes as
described and the "click" of
the fuel solenoid is
detected, the problem is
most likely an engine
control problem prohibiting
the vehicle from starting.
*If the voltage changes as
described but the "click" of
the fuel solenoid is NOT
detected then the problem
is most likely a failed
solenoid in the fuel
module.
*If the problem cannot be
resolved, call 866-310-
4345 for technical
assistance.
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