Diagnostic Test

CHECKING FOR THE POWER CONTROL RELAY NOT DISCONNECTING PROPERLY WHEN COMMANDED (P2AF6): 

It can be difficult to test the power control relay for properly disconnecting during an engine cranking event without using a lab scope. This is due to the relay only being energized (opened) for approximately 20-40ms.

TECH TIPS: 

• The normally closed power control relay should be closed 99% of the time. It is only opened by the PCM during the starter in-rush at Stop /Start engine cranking.

1. The power control relay is located in the PDC. Disconnect the power control relay  connector. Load test the power control relay coil ground circuit.
   1. If the ground circuit fails the load test, repair the ground circuit for an open or high resistance.
   2. If the ground circuit passes the load test, reconnect the power control relay connector for the next step. 
      • Continue to step 2 to test without a lab scope  .
      • Continue to step 4 to test with a lab scope  .
2. The power control relay should energize and open when battery voltage is supplied to the relay on the control circuit which comes from the output of the PCR control relay inside the PDC. The PCR control relay is typically a Printed Circuit Board (PCB) relay which cannot be removed and jumped across. To energize the power control relay:
   1. If there is an actuator available in the scan tool, command the power control relay on.
   2. Back probe the PCR control relay low side driver control circuit at the PDC connector and connect to chassis ground to energize the relay. Back probe the Starter Relay 1 control circuit at the PDC connector and connect to chassis ground to energize the relay.
   3. Continue to step 3 
3. With battery voltage provided to the power control relay, measure the voltage at the C3-1 and C8-1 cable end terminals at the PDC. Verify that the ignition is on to provide a load on the auxiliary battery. If the relay is disconnected, the voltage on the auxiliary battery terminal should start to drop below the voltage on the main battery terminal due to the load on the auxiliary battery.
   1. If the voltage starts to drop on the terminal that leads to the auxiliary battery, the power control relay is functioning properly. Check each of the following:
      • Check the fuses between the positive battery cable connections at the PDC and batteries.
      • Check both battery ground cables for poor ground connections.
      • Check both battery positive cable connections at the PDC and batteries for poor connections.
   2. If the voltage drops drastically below approximately 8V on the terminal connected to the auxiliary battery, isolate and test the auxiliary battery with the approved battery tester.
   3. If the voltage at both terminals remains the same, determine if the fault is in the relay or the PDC
      • Check for battery voltage of the fuse at the output PCR control relay. If there battery voltage is present, replace the PCR in accordance with the service information and retest. If battery voltage is not present, replace the PDC in accordance with the Service Information.
      • Perform an IBS reset by removing the IBS from the battery cable end and disconnecting the IBS harness connector for 30 seconds after an auxiliary battery is charged or replaced. This will allow the IBS to default to an 80% SOC and initiate the quick learning curve.
4. To test with a lab scope:
   • Connect channel A to the C8-1 terminal of the PDC (Auxiliary battery connection)
   • Connect channel B to the C3-1 terminal of the PDC (Main battery connection)
   • Connect channel C to the fuse for the power control relay output in the PDC
   • Back probe the PCR control relay low side driver control circuit at the PDC connector and connect to chassis ground to energize the relay.

   Set the channels to the 20V scale. Crank the engine and record the voltage reads. The voltage on the main battery (channel B) side should drop considerably during cranking. At initial starter in-rush the voltage can drop as low as 7.0V. If the power control relay is operating correctly you should simultaneously see approximately battery voltage present on the control circuit (channel C), and the auxiliary battery side voltage (channel A) should stay near battery voltage during cranking. Channel C should stay near battery voltage because the PCR control relay is energized.

   1. If the auxiliary battery voltage (channel A) stays near battery voltage as the main battery voltage (channel B) drops during cranking, the power control relay is functioning properly. Check each of the following:
      • Check the fuses between the positive battery cable connections at the PDC and batteries.
      • Check both battery ground cables for poor ground connections.
      • Check both battery positive cable connections at the PDC and batteries for poor connections.
   2. If the auxiliary battery voltage (channel A) stays the same as the main battery voltage (channel B) when the voltage drops at initial cranking, the power control relay likely did not open.
      • If battery voltage was present on the control circuit (channel C), the relay is faulty. Replace the power control relay in accordance with the service information and retest.
      • If the battery voltage was NOT present on the control circuit (channel C), the power control relay is not the issue. Check the control circuit and fuse for the power control relay for an open. If the fuse is open, check the circuit for a short to ground. If the circuit and fuse check good, replace the PDC in accordance with the Service Information.
   3. If the auxiliary battery voltage (channel A) drops severely (below approximately 8.0V) but is not the same as the main battery voltage (channel B) at initial cranking, the auxiliary battery is likely faulty or severely undercharged. Continue to the CHECKING FOR A DEPLETING OR DEPLETED BATTERY information below to test the auxiliary battery using the approved Battery Tester.

CHECKING FOR A DEPLETING OR DEPLETED BATTERY: Previous service information reported never to blind charge the battery around the Intelligent Battery Sensor (IBS). Software changes to the approved Mopar® battery tester has improved how the battery is tested. However, this requires the approved Mopar® battery tester to be connected directly to the battery posts, bypassing the IBS. 

1. Disconnect the battery positive and negative cables to isolate the battery. If both batteries are not disconnected, the positive cable will still have voltage through it's connection to the other battery. Isolate the positive cable end so that it cannot touch ground or disconnect both batteries to be certain the 12 volt system is powered down. Connect the approved battery tester directly to the battery posts and select the battery charging and testing procedure on the screen.
2. Follow the prompts on the approved Mopar® battery tester screen and fill in the vehicle information.
3. When the battery test has completed, the tester will display the results on the screen.
4. While viewing the battery test result, press the CODE button and the tester will prompt you for the last 4 digits of the Vehicle Identification Number (VIN). Use the UP/DOWN arrow buttons to scroll to the correct character; then press ENTER to select and move to the next digit. Then press the ENTER button to view the SERVICE CODE. Pressing the CODE button a second time will return you to the test results.
   1. If the battery fails the load testing below, record the failure code and replace the battery.
   2. If the battery DOES NOT fail the load testing below, reconnect the battery and retest the system. If the battery, starting and charging systems test good, but the battery discharges after sitting, check the electrical system for an ignition off draw. Refer to IGNITION OFF DRAW TEST .