Table 1. 291 Demand Fan Solenoid Diagnostic Codes - Continued.
CID FMI CODE
TEST OR INSPECTION
291-5 Demand Fan Solenoid
Current Below Normal
· Always inspect wiring harness connectors that are involved in the circuit.
Poor connections can often be the cause of a problem in an electrical
circuit. Verify that all connections in the circuit are clean and secure and
that all connections are in good condition. If a problem with the
connection is found, correct the problem and verify that this malfunction
or diagnostic code is active before performing this procedure.
· Perform open or short-circuit test at each wiring harness connection to
identify the correct wiring harness to replace.
· Tag all wiring harnesses to aid in installation.
· Perform this test only if condition is active.
DIAGNOSTIC CODE SET CONDITION
Transmission ECM detects an open circuit or low current condition in the demand
· Lower cab wiring harness high resistance or open.
· Rear frame wiring harness high resistance or open.
Test Step 1. Check for Active
Connect MSD. Select Transmission
Diagnostic Code 291-5 Active -
Proceed to Test Step 2.
924H and check for active diagnostic
Diagnostic Code 291-5 Not Active -
Troubleshooting is complete.
Test Step 2. Test Lower Cab Wiring
Harness for High Resistance or
1. Turn ignition switch and battery
disconnect switch to OFF position
2. Remove fan (WP 0234).
3. Disconnect connector M-C16
demand fan solenoid.
4. Connect jumper wire between
terminal 1 and terminal 2 of
5. Remove left lower cab access
panels (WP 0347).
6. Remove transmission ECM cover