Fuse, Caution – Proheat X45–School Bus User Manual

Page 92

5-35

SECTION 5. TROUBLESHOOTING & REPAIR

FUSE

If, when the heater is switched “ON,” the heater does not run and the “ON”

light does not light, check the fuse in the PCM. The fuse will blow if there is a

short to ground in a positive lead or internally for the following components:

• ON/OFF Switch

• Coolant Pump

• Air Compressor/Fuel Pump

• Blower

• Ignition Coil

• Internal Wire Harness

Reversing polarity at the battery will also cause the fuse to blow. This will not

harm the PCM.

Check: Heater wiring. See flow chart Figure 5-28 on next page.

Figure 5-27

Internal Wire Harness Test

3 2 1

HARNESS TO

COMPONENTS

PIN LOCATIONS MOLDED

INTO CONNECTOR

COIL

COOLANT PUMP

COMPRESSOR

BLOWER

GROUND ON
HEAT EXCHANGER

FUSE

CAUTION

Repeated replacement of the fuse

or using incorrectly rated fuses

without correcting the problem,

can damage the PCM.

5.2.8

This manual is related to the following products: