C1401

C1401- TRANSFER CASE RANGE SELECT SWITCH CIRCUIT LOW





For a complete wiring diagram, refer to Wiring Diagram Information.
^ When Monitored:
With the ignition on.
^ Set Condition:
Transfer Case Range Select Switch voltage less than 0.1568 volts for 5 seconds

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

Diagnostic Test
1. TCASE (DTCM) SWITCH VOLTAGE LESS THAN 0.2 VOLTS
Ignition on, engine not running.
With the scan tool under Data Display, read the TCASE (DTCM) Switch voltage.
Is the voltage less than 0.2 volts?
Yes >>Go To 2
No >>Go To 9

2. (K77) 5 VOLT SELECTOR SWITCH SUPPLY CIRCUIT VOLTAGE LESS THAN 0.2 VOLTS





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 less than 0.2 volts?
Yes >>Go To 3.
No >>Go To 5.

3. (K77) 5 VOLT SELECTOR SWITCH SUPPLY CIRCUIT OPEN





Turn the ignition off.
Disconnect the Instrument Cluster C1 connector.
Measure the resistance of the (K77) 5 Volt Selector Switch Supply circuit.
Is the resistance greater than 5.0 ohms?
Yes >>Repair the (K77) 5 Volt Selector Switch Supply circuit for an open.
Perform the TRANSFER CASE VERIFICATION TEST VER 1. Transfer Case Verification Test
No >>Go To 4

4. (K77) 5 VOLT SELECTOR SWITCH SUPPLY CIRCUIT SHORTED TO GROUND





Measure the resistance between the (K77) 5 Volt Selector Switch Supply circuit and ground.
Is the resistance less than 5.0 ohms?
Yes >>Repair the (K77) 5 Volt Selector Switch Supply circuit for a short to ground.
Perform the TRANSFER CASE VERIFICATION TEST VER 1. Transfer Case Verification Test
No >>Go To 8

5. TRANSFER CASE SELECTOR SWITCH





Turn the ignition off.
Connect a jumper wire between the 5 Volt Selector Switch Supply circuit and the Mode Select circuit in the Transfer Case Selector Switch connector.
Ignition on, engine not running.
With the scan tool in Data Display, read the Range Switch voltage.
The switch voltage should be approximately 5 volts.
Does the voltage display as described?
Yes >>Replace the Transfer Case Selector Switch. Perform the TRANSFER CASE VERIFICATION TEST VER 1. Transfer Case Verification Test
No >>Go To 6

6. (K977) MODE SELECT CIRCUIT SHORT TO GROUND





Measure the resistance between the (K977) Mode Select circuit and ground.
Is the resistance less than 5.0 ohms?
Yes >>Repair the (K977) Mode Select circuit for a short to ground.
Perform the TRANSFER CASE VERIFICATION TEST VER 1. Transfer Case Verification Test
No >>Go To 7

7. (K977) MODE SELECT CIRCUIT OPEN





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. Transfer Case Verification Test
No >>Go To 8

8. INSTRUMENT CLUSTER
View repair.
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

9. 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. Transfer Case Verification Test
No >>Test complete.