Table 1. 70 Parking Brake Switch Diagnostic Codes.
CID FMI CODE
TEST OR INSPECTION
70-3 Parking Brake Switch
Voltage Is Above 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 status of both parking brake disengaged and
engaged inputs are open.
· Parking brake limit switch is faulty.
· Lower cab wiring harness is open.
· Cab ground is open.
· Transmission ECM.
Test Step 1. Check for Active
Connect MSD, select Transmission
Diagnostic Code 70-3 Active -
Proceed to Test Step 2.
924H and check for active diagnostic
Diagnostic Code 70-3 Not Active -
Troubleshooting is complete.
Test Step 2. Test for Faulty Parking
Brake Limit Switch.
1. Turn ignition switch and battery
disconnect switch to OFF position
2. Remove parking brake limit switch