Table 1. 590 Communication Diagnostic Codes.
CID FMI CODE
TEST OR INSPECTION
Communication Data Is
· Always inspect wiring harness connectors that are involved in the circuit.
Erratic, Intermittent, or
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 cannot communicate with the engine ECM or the ECM
appears to work intermittently.
· Lower cab wiring harness is open.
· Lower cab wiring harness is shorted to voltage.
· Lower cab wiring harness is shorted to ground.
· Engine wiring harness is open.
· Engine wiring harness is shorted to voltage.
· Engine wiring harness is shorted to ground.
· Engine ECM.
Test Step 1. Check for Active
Connect MSD. Select Transmission
Diagnostic Code 590-2 Active -
924H and check for active diagnostic
Proceed to Test Step 2.
Diagnostic Code 590-2 Not Active -
Troubleshooting is complete.
Test Step 2. Test Wiring Harness for
1. Turn ignition switch and battery
disconnect switch to OFF position