Table 1. 420 Secondary Steering System Diagnostic Codes.
CID FMI CODE
TEST OR INSPECTION
420-7 Secondary Steering
System Is Not Responding
· 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 the machine is moving via the transmission output
speed sensor and secondary steering enable relay is energized, but the
secondary steering relay has no output to the secondary steering motor.
· Secondary steering enable relay faulty.
· Secondary steering relay faulty.
· Lower cab wiring harness.
· Rear frame wiring harness.
· Secondary steering wiring harness.
· Transmission ECM.
This fault occurs only when the machine is moving; therefore, it will be a
logged fault in the ECM. This fault indicates that secondary steering has
failed or feedback to the ECM is faulty.
Test Step 1. Check for Active
Connect MSD. Select Transmission
Diagnostic Code 420-7 Active -
Proceed to Test Step 2.
924H and check for active diagnostic
Diagnostic Code 420-7 Not Active -
Troubleshooting is complete.