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.

ACTIVE DTC
NOTE:
Diagnose and repair any system voltage or 5-Volt reference DTCs before continuing with this test.

NOTE:
Make sure the A/C refrigerant System is properly charged in accordance with the service information. Refer to SPECIFICATIONS .
1. Start the engine and allow it to reach normal operating temperature.
  WARNING:
  When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in possible serious or fatal injury.
2. With the scan tool, select View DTCs.
  Is the DTC Active at this time?
  
  Yes
  - Go To 2
  No
  - Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
CHECK THE (C818) 5-VOLT SUPPLY CIRCUIT VOLTAGE
1. Turn the ignition off.
2. Disconnect the A/C Pressure Transducer harness connector.
3. Turn the ignition on.
4. Measure the voltage of the (C818) 5-Volt Supply circuit at the A/C Pressure Transducer harness connector.
  Is the voltage above 4.8 volts?
  
  Yes
  - Go To 6
  No
  - Go To 3
CHECK THE (C818) 5-VOLT SUPPLY CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition on.
2. Disconnect the PCM C1 harness connector.
3. Measure the resistance between ground and the (C818) 5-Volt Supply circuit at the A/C Pressure Transducer harness connector.
  Is the resistance above 10k Ohms?
  
  Yes
  - Go To 4
  No
  - Repair the (C818) 5-Volt Supply circuit for a short to ground.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 16V Turbo .
CHECK FOR THE (C818) 5-VOLT SUPPLY CIRCUIT SHORTED TO THE (K914) SENSOR GROUND CIRCUIT
1. Measure the resistance between the (C818) 5-Volt Supply circuit and the (K914) Sensor Ground circuit at the A/C Pressure Transducer harness connector.
  Is the resistance above 10k Ohms?
  
  Yes
  - Go To 5
  No
  - Repair the short between the (C818) 5-Volt Supply circuit and the (K914) Sensor Ground circuit.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 16V Turbo .
CHECK THE (C818) 5-VOLT SUPPLY CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (C818) 5-Volt Supply circuit between the A/C Pressure Transducer harness connector and the PCM C1 harness connector.
  Is the resistance below 5.0 Ohms?
  
  Yes
  - Go To 10
  No
  - Repair the (C818) 5-Volt Supply circuit for an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 16V Turbo .
CHECK THE (C18) A/C PRESSURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition off.
2. Disconnect the PCM C1 harness connector.
3. Measure the resistance between ground and the (C18) A/C Pressure Sensor Signal circuit in the A/C Pressure Transducer harness connector.
  Is the resistance above 10k Ohms?
  
  Yes
  - Go To 7
  No
  - Repair the (C18) A/C Pressure Sensor Signal circuit for a short to ground.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 16V Turbo .
CHECK FOR THE (C18) A/C PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO THE (K914) SENSOR GROUND CIRCUIT
1. Measure the resistance between the (C18) A/C Pressure Sensor Signal circuit and the (K914) Sensor Ground circuit in the A/C Pressure Transducer harness connector.
  Is the resistance above 10k Ohms?
  
  Yes
  - Go To 8
  No
  - Repair the (C18) A/C Pressure Sensor Signal circuit for a short to the (K914) Sensor Ground circuit.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 16V Turbo .
CHECK THE (C18) A/C PRESSURE SENSOR SIGNAL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (C18) A/C Pressure Sensor Signal circuit between the A/C Pressure Transducer harness connector and the PCM C1 harness connector.
  Is the resistance below 5.0 Ohms?
  
  Yes
  - Go To 9
  No
  - Repair the (C18) A/C Pressure Sensor Signal circuit for an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 16V Turbo .
AC PRESSURE TRANSDUCER
1. Turn the ignition off.
2. Reconnect the PCM C1 harness connector.
3. Connect a jumper between the (C818) 5-Volt Supply circuit and the (C18) A/C Pressure Sensor Signal circuit at the A/C Pressure Transducer harness connector.
4. Turn the ignition on.
5. With the scan tool, read the AC Pressure Transducer signal voltage.
  Is the voltage above 4.8 volts with the jumper wire in place?
  
  Yes
  - Replace the A/C Pressure Transducer in accordance with the service information. Refer to TRANSDUCER, A/C PRESSURE, REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 16V Turbo .
  No
  - Go To 10
POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the A/C Pressure Transducer and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Perform any Technical Service Bulletins that may apply.
  Were any problems found?
  
  Yes
  - Repair as necessary.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 16V Turbo .
  No
  - Replace and program the Powertrain Control Module (PCM) in accordance with the service information. Refer to MODULE, POWERTRAIN CONTROL, REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 16V Turbo .