Initial Inspection and Diagnostic Overview
Radiator Cooling Fan Motor: Symptom Related Diagnostic Procedures
Coolant Fan Does Not Run
Refer to SCHEMATIC DIAGRAMS/ELECTRONIC AND ELECTRICAL DIAGRAMS for wiring schematics.
1.
Connect fused jumper between ALDL connector terminal B and ground and turn ignition switch to RUN position. If coolant fan runs, problem is
ECM related.
2.
If coolant fan does not run, connect fused jumper between dark green/white wire of ECM connector C1 (VIN R) or C3 (VIN W) and ground and
turn ignition switch to RUN position. If coolant fan runs, problem is ECM related.
3.
If coolant fan does not run, leave fused jumper connected as in step 2, disconnect coolant fan relay connector, turn ignition switch to RUN position
and connect test lamp between terminals as follows:
a. Between D wire terminal and ground. If lamp does not illuminate, check C/H fuse and brown/white wire for open.
b. Between D and F wire terminals. If lamp does not illuminate, check dark green/white wire for open.
c. Between red wire terminal and ground. If lamp does not illuminate, check red wire and fusible link A for open.
4.
If lamp illuminates in steps a, b and c, disconnect coolant fan relay connector and connect fused jumper between A and E wire terminals. If coolant
fan runs, replace coolant fan.
5.
If coolant fan does not run, leave fused jumper connected as in step 4, disconnect coolant fan connector and connect test lamp between terminals
as follows:
a. Between B wire terminal and ground. If lamp does not illuminate, check black/red wire (VIN R and T) or yellow wire (VIN W and T) for
open.
b. Between B and black wire terminals. If lamp does not illuminate, check black wire for open.
c. If lamp illuminates in steps a and b, replace coolant fan.
Coolant Fan Runs Continuously
Refer to SCHEMATIC DIAGRAMS/ELECTRONIC AND ELECTRICAL DIAGRAMS for wiring schematics.
1.
Place ignition switch in RUN position, disconnect ECM connector C1 on VIN R or C3 on VIN T. If coolant fan does not turn off, proceed to step
2. If coolant fan turns off, problem is ECM related.
2.
Remove FAN/ELEC fuse. If fan turns off, locate and repair short to ground in dark green/white wire. If fan stays on, replace coolant fan relay.
