JLG 340AJ Service Manual - Manual (Page 114)

SECTION 3 - CHASSIS & TURNTABLE
3-74 – JLG Lift – 3121259
Coolant Sensor
The coolant sensor operates by providing variable resistance
to ground based on coolant temperature.
Glow Plugs
The diesel engine has three in-cylinder glow plugs to assist in
cold starting. The ground module controls the glow plugs and
uses a relay to switch battery current.
Figure 3-54. Engine Coolant Sensor
+5V
270 Ohm
J1-15 Input
Engine Block
Ground
Ground Module
Engine Oil Pressure
Switch
Open for Normal Pressure
Closed for Low Pressure
Figure 3-55. Engine Coolant Sensor Schematic
VBatt
J1-12 put Out
Glow Plugs
Glow Plug Relay
Ground Module
- +
Figure 3-56. Engine Glow Plug Schematic
Figure 3-57. Glow Plug Relay