JLG 460SJ Service Manual - Manual (Page 173)

SECTION 3 - CHASSIS & TURNTABLE
3120895 – JLG Lift – 3-121
Engine Control Module Replacement
REMOVAL
1. Disconnect Negative battery cable.
2. Remove controller from mounting bracket.
3. Push connector lock back to unlock connector.
4. Unplug controller and remove.
INSTALLATION
THE CONTROLLER IS CALIBRATED FOR EACH ENGINE VERIFY
YOU HAVE THE CORRECT CONTROLLER
1. Plug connector into controller.
2. Push lock into place.
3. Mount controller into mounting bracket.
4. Reconnect the battery cable.
5. Start engine.
6. Check for any DTC codes and clear.
7. Verify engine is in closed loop and no warning lights
are illuminated.
Heated Exhaust Gas Oxygen Sensor
Replacement
REMOVAL
1. Disconnect Negative battery cable.
2. Disconnect the O2 sensor electrical connector.
3. Using an O2 Sensor socket, remove the O2 Sensor
and discard.
INSTALLATION
BEFORE INSTALL THE O2 SENSOR LUBRICATE THREADS WITH
ANTI-SEIZE COMPOUND GM P/N 5613695 OR EQUIVALENT.
AVOID GETTING COMPOUND ON THE SENSOR TIP.
1. Install O2 sensor. Tighten to 30 lb-ft (41 Nm).
2. Start engine.
3. Check for any DTC codes and clear.
4. Verify engine is in closed loop and no warning lights
are illuminated.
3.28 GM ENGINE LPG FUEL SYSTEM
DIAGNOSIS
Fuel System Description
To maintain fuel and emission control on the LPG fuel sys-
tem the Engine Control Units (ECM) relies on numerous
engine sensor and output data from the Electronic Pres-
sure Regulator (EPR). The ECM will then determine the
target fuel calibration and command the EPR to reposition
the voice coil to the proper position which, subsequently
reposition the secondary lever in the pressure regulator to
maintain proper control. The EPR and ECM will continue
to communicate back and forth during normal operation.
In the event that the EPR fails to communicate or the Com-
munications Area Network (CAN) cable fails to transmit
data the regulator will operate in an open loop configura-
tion. As the air valve vacuum in the mixer venturi is com-
municated to the secondary chamber of the regulator the
secondary diaphragm will be drawn in a downwards
motion. This downward motion will cause the secondary
lever to open thus allowing more fuel to enter the mixer.
In the (LPR) the fuel is vaporized and the pressure
reduced in two stages. The first stage reduces the pres-
sure to approximately 1.0 to 3.0 psi (6.8 to 20.6 kPa). The
second stage reduces the pressure to approximately neg-
ative 1.5" of water column.
The fuel is then drawn from the secondary chamber of the
LPR by the vacuum generated by air flowing through the
mixer. This vacuum signal is also used to generate lift for
the mixer air valve. This vacuum signal is most commonly
referred to as air valve vacuum. In the mixer, the fuel mixes
with the air entering the engine. This air/ fuel mixture is
then drawn into the engine for combustion.
Figure 3-80. EPR Assembly