C1402

C1402-TRANSFER CASE RANGE SELECT SWITCH CIRCUIT HIGH





When Monitored:
With the ignition on.

Set Condition:
Transfer Case Range Select Switch voltage greater than 4.86 volts for 5 seconds

Possible Causes
- INTERMITTENT CONDITION
- (K77) 5 VOLT SELECTOR SWITCH SUPPLY CIRCUIT SHORTED TO VOLTAGE
- (K977) MODE SELECT CIRCUIT SHORTED TO VOLTAGE
- (K977) MODE SELECT CIRCUIT OPEN
- (Z973) TRANSFER CASE SELECTOR SWITCH GROUND CIRCUIT OPEN
- TRANSFER CASE SELECTOR SWITCH
- INSTRUMENT CLUSTER

Diagnostic Test
1. TCASE (DTCM) SWITCH VOLTAGE ABOVE 4.8 VOLTS





Ignition on, engine not running.
With the scan tool under Data Display, read the TCASE (DTCM) Switch voltage.
Is the voltage above 4.8 volts?
Yes >>Go To 2
No >>Go to 8

2. (K77) 5 VOLT SELECTOR SWITCH SUPPLY CIRCUIT SHORTED TO VOLTAGE





Turn the ignition off.
Disconnect the Transfer Case Selector Switch connector.
Turn the ignition on.
Measure the voltage of the (K77) 5 Volt Selector Switch Supply circuit.
Is the voltage above 5.5 volts?
Yes >>Repair the (K77) 5 Volt Selector Switch Supply circuit for a short to voltage.
Perform the TRANSFER CASE VERIFICATION TEST VER 1. Transfer Case Verification Test
No >>Go to 3

3. (K977) MODE SELECT CIRCUIT SHORTED TO VOLTAGE





Measure the voltage of the (K977) Mode Select circuit.
Is the voltage above 5.5 volts?
Yes >>Repair the (K977) Mode Select circuit for a short to volt age.
Perform the TRANSFER CASE VERIFICATION TEST VER 1.
No >>Go to 4

4. TRANSFER CASE SELECTOR SWITCH





Turn the ignition off.
Connect a jumper wire between the (Z973) ground circuit and the (K977) Mode Select circuit in the Transfer Case Selector Switch connector.
Ignition on, engine not running.
With the scan tool under Data Display, read the TCASE (DTCM)
Switch voltage.

Note: Remove the jumper wire before continuing.

Is the voltage below 0.2 volts with the jumper wire in place?
Yes >>Replace the Transfer Case Selector Switch.
Perform the TRANSFER CASE VERIFICATION TEST VER 1.
No >>Go to 5

5. (K977) MODE SELECT CIRCUIT OPEN





Turn the ignition off.
Disconnect the Instrument Cluster C2 connector.
Measure the resistance of the (K977) Mode Select circuit.
Is the resistance above 5.0 ohms?
Yes >>Repair the (K977) Mode Select circuit for an open.
Perform the TRANSFER CASE VERIFICATION TEST VER 1.
No >>Go To 6

6. TRANSFER CASE SELECTOR SWITCH (Z973) GROUND CIRCUIT OPEN





Measure the resistance of the Transfer Case Selector Switch (Z973) ground circuit.
Is the resistance above 5.0 ohms?
Yes >>Repair the Transfer Case Selector Switch (Z973) ground circuit for an open.
Perform the TRANSFER CASE VERIFICATION TEST VER 1.
No >>Go To 7

7. INSTRUMENT CLUSTER
Repair
Replace the Instrument Cluster in accordance with the Service Information.
Perform the BODY VERIFICATION TEST-VER 1 and TRANSFER CASE VERIFICATION TEST-VER 1. Transfer Case Verification Test

8. INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
While monitoring the scan tool data relative to this circuit, wiggle test the wiring and connectors.
Look for the data to change or for the DTC to reset during the wiggle test.
Were any problems found?
Yes >>Repair as necessary.
Perform the TRANSFER CASE VERIFICATION TEST-VER 1.
No >>Test complete.