Table 1. 668 Transmission Control Shift Lever Diagnostic Codes.
CID FMI CODE
TEST OR INSPECTION
668-2 Transmission Control
Shift Lever Data Is Erratic,
· Always inspect wiring harness connectors that are involved in the circuit.
Intermittent, or Incorrect
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 erratic signal, an intermittent signal, or an incorrect
signal from the transmission control shift lever.
· Transmission control shift lever is faulty.
· Shift lever remote is faulty.
· Lower cab wiring harness is open.
· Lower cab wiring harness is shorted.
· Transmission fuse is faulty.
· Transmission ECM.
Test Step 1. Check for Active
Connect MSD. Select Transmission
Diagnostic Code 668-2 Active -
924H and check for active diagnostic
Proceed to Test Step 2.
Diagnostic Code 668-2 Not Active -
Troubleshooting is complete.
Test Step 2. Test for Faulty
Transmission Control Shift Lever.
1. Turn ignition switch and battery
disconnect switch to OFF position