Diagnostic Test

WARNING: This page is about a different car, the 2015 Fiat 500. However, it is still accessible from the selected car via links, so may be relevant.

TEST FOR INTERMITTENT CONDITION
NOTE:
Check for any TSB(s) related to the condition. If a TSB applies, perform the procedure outlined in the TSB before continuing.
1. Turn the ignition on.
  NOTE:
  Make sure the battery voltage is between 10.0 and 16.0 volts.
2. With the scan tool, read the module status.
  NOTE:
  Check the BCM for any active CAN hardware DTCs, perform DTC before proceeding.
  
  Does the scan tool indicate that the module is active on the bus?
  
  Yes
  - The no response condition is not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring for chafed, pierced, pinched, and partially broken wires and the wiring harness connectors for broken, bent, pushed out, and corroded terminals.
  - Perform the BODY VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  No
  - Go To 2
CHECK THE FUSED B(+) CIRCUIT FOR AN OPEN OR SHORT
1. Turn the ignition off.
2. Disconnect the A/C Heater Module harness connectors.
3. Using a 12-volt test light connected to ground, check the Fused B(+) circuit.
  Does the test light illuminate brightly?
  
  Yes
  - Go To 3
  No
  - Repair the open or short in the Fused B(+) circuit.
  - Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .
CHECK THE GROUND CIRCUIT FOR AN OPEN
1. Using a 12-volt test light connected to 12-volts, check the Ground circuit.
  Does the test light illuminate brightly?
  
  Yes
  - Go To 4
  No
  - Repair the open in the Ground circuit.
  - Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .
CHECK THE FUSED IGNITION RUN RELAY OUTPUT CIRCUIT FOR AN OPEN OR SHORT
1. Turn the ignition on.
2. Using a 12-volt test light connected to ground, check the Fused Ignition Run Relay Output circuit.
  Does the test light illuminate brightly?
  
  Yes
  - Go To 5
  No
  - Repair the open or short in the Fused Ignition Run Relay Output circuit.
  - Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .
CHECK THE CAN IHS BUS (125K) CIRCUIT FOR AN OPEN
1. Turn the ignition off.
2. Disconnect the CAN IHS IP C6 Star Connector.
3. Measure the resistance of the CAN IHS Bus (-) (125K) circuit between the CAN IHS IP C6 Star Connector and the A/C Heater harness connector.
4. Measure the resistance of the CAN IHS Bus (+) (125K) circuit between the CAN IHS IP C6 Star Connector and the A/C Heater harness connector.
  Are the resistances below 5.0 Ohms?
  
  Yes
  - Replace the A/C Heater Module in accordance with the Service Information. Refer to MODULE, A/C AND HEATER, REMOVAL .
  - Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  No
  - Repair the open in the CAN IHS Bus (125K) circuit. Inspect the connector for damage.
  - Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .