2014 Jeep Wrangler JK Factory Service Manual 28 - DTC-Based Diagnostics

B1138-CABIN HEATER 3 CONTROL CIRCUIT LOW

For a complete wiring diagram, refer to the Wiring Information.



Possible Causes

(W24) FUSED RUN RELAY OUTPUT CIRCUIT OPEN
(K363) CABIN HEATER RELAY 3 CONTROL CIRCUIT SHORTED TO GROUND
(K363) CABIN HEATER RELAY 3 CONTROL CIRCUIT OPEN
CABIN HEATER RELAY 3
TOTALLY INTEGRATED POWER MODULE (TIPM)

1. VERIFY THAT THE DIAGNOSTIC TROUBLE CODE (DTC) IS ACTIVE

1. Ignition on, engine not running.
2. Using the scan tool, read and record TIPM DTCs.


NOTE: Record the Environmental Data for all DTCs before erasing. The Environmental Data can help in duplicating the conditions in which the DTC originally set.
3. Using the scan tool, erase TIPM DTCs.
4. Using the scan tool, actuate the Cabin Heater 3 Relay and allow the actuator to run for a least of two minutes.
5. Using the scan tool, read TIPM DTCs.


Did this DTC reset?

Yes


No


2. CHECK THE CABIN HEATER RELAY 3

1. Turn the ignition off to the lock position.
2. Install a substitute relay for the Cabin Heater Relay 3.


NOTE: Check connectors - Clean/repair as necessary.
3. Ignition on, engine not running.
4. Using the scan tool, erase TIPM DTCs.
5. Using the scan tool, actuate the Cabin Heater Relay 3 and allow the actuator to run for a least of two minutes.
6. Using the scan tool, read TIPM DTCs.


Did this DTC reset?

Yes


No


3. CHECK THE (W24) FUSED RUN RELAY OUTPUT CIRCUIT FOR AN OPEN
1. Turn the ignition off to the lock position.
2. Remove the substitute Cabin Heater Relay 3.
3. Ignition on, engine not running.
4. With a 12-volt test light connect to ground, check the (W24) Fused Run Relay Output circuit in the Cabin Heater Relay 3 connector.


NOTE: The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.


Does the test light illuminate brightly?

Yes


No


4. CHECK (K363) CABIN HEATER RELAY 3 CONTROL CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition off to the lock position.
2. Disconnect the TIPM C1 harness connector.
3. Measure the resistance between ground and the (K363) Cabin Heater Relay 3 Control circuit.


Is the resistance below 100k Ohms?

Yes


No


5. CHECK (K363) CABIN HEATER RELAY 3 CONTROL CIRCUIT FOR AN OPEN
1. Measure the resistance of the (K363) Cabin Heater Relay 3 Control circuit between the Cabin Heater Relay 3 connector and the TIPM C1 harness connector.


Is the resistance below 1.0 Ohm?

Yes


No


6. CHECK THE WIRING AND CONNECTORS

1. The conditions necessary to set the DTC are not present at this time.
2. Using the scan tool, check the Environmental Data to help identify the conditions in which the DTC originally set.
3. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
4. Check for an intermittent condition by inspecting the related wiring harness for chafed, pierced, pinched, or partially broken wires.
5. Check the connectors for broken, bent, pushed out, spread, corroded, or contaminated terminals.
6. Wiggle the wiring and connectors while checking for shorted and open circuits.


Were there any problems found?

Yes


No