Caution, Overheat diagnostic code 4, Warning – Proheat M125 User Manual
Page 62
4-25
PROHEAT M-SERIES G-II PCM SERVICE MANUAL
4.1.5
(4 Flashes)
CAUTION
Repeatedly resetting the PROHEAT
without resolving the Overheat
diagnostic code will damage the
heat exchanger.
Procedure – Mechanical inspection and testing:
a)
Connect the power directly to the Coolant Pump. Observe the operation.
If the Motor does not operate, replace the Coolant Pump.
OVERHEAT Diagnostic Code 4
Indicates that the Temperature Sensor detected an inner heat exchanger
surface temperature of 257°F (125°C). The G-II PCM will detect overheats
even if the heater is not switched on.
Troubleshoot the Overheat diagnostic code based on:
1.
Lack of coolant, air or flow problems in the coolant system.
Go to page 4-24, Steps 1 and 2.
2.
Faulty Temperature Sensor. Go to page 4-27.
3.
Faulty G-II PCM Temperature Sensor circuit. Go to page 4-27.
An Overheat will put the heater in Lockout Mode (requires power to the G-II
PCM to be removed and reapplied) on the first occurrence of an Overheat.
Figure 4-26: G-II PCM Coolant Pump Output Voltage Measurement.
A
B
RED (+)
BLACK (-)
WARNING
NEVER remove coolant lines when
the engine/system is HOT – escaping
steam or scalding water could cause
serious personal injury. Loosen the
coolant line clamps slowly, allowing
the pressure to escape before
removing completely.