Diagnostic Test

BRAKE FLUID LEVEL SWITCH SIGNAL VOLTAGE ABOVE 4.9 VOLTS
WARNING: On vehicles equipped with the high voltage system, you must thoroughly read and follow all High Voltage Safety procedures. In addition, before performing any diagnostic or service procedure near a high voltage component, you must perform the High Voltage Power Down. Failure to follow these instructions may result in possible serious or fatal injury. Refer to Electrical - Engine Systems/Battery System - Warning

NOTE: This DTC must be active for the results of this test to be valid.
1. Turn the ignition on.
2. With the scan tool, read Brake Fluid Level Switch Signal voltage.
  Is the voltage above 4.9 volts?
  
  Yes
  - Go to step 2
  No
  - Perform the ABS INTERMITTENT CONDITION TEST. Refer to DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure .
(B20) BRAKE FLUID LEVEL SWITCH SIGNAL CIRCUIT FOR SHORT TO BATTERY VOLTAGE

Fig 1: Checking Brake Fluid Level Switch Signal Circuit
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. Disconnect the Brake Fluid Level Switch harness connector.
3. Turn the ignition on.
4. Measure the voltage of the (B20) Brake Fluid Level signal circuit in the Brake Fluid Level Switch harness connector to ground.
  Is the voltage above 5.2 volts?
  
  Yes
  - Repair the (B20) Brake Fluid Level signal circuit for a short to voltage.
  - Perform ABS VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure .
  No
  - Go to step 3
BRAKE FLUID LEVEL SWITCH INTERNAL FAILURE

Fig 2: Checking Brake Fluid Level Signal Circuit
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. Connect a jumper wire between the (B20) Brake Fluid Level signal circuit and the (Z420) Brake Fluid Level ground circuit in the Brake Fluid Level Switch harness connector
3. Turn the ignition on.
4. With the scan tool, read the Brake Fluid Level Switch voltage
  Is the voltage below 1.0 volt?
  
  Yes
  - Replace the Brake Fluid Level Switch in accordance with the Service Information.
  - Perform ABS VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure .
  No
  - Go To step 4
(B20) BRAKE FLUID LEVEL SWITCH CIRCUIT OPEN

Fig 3: Checking Brake Fluid Level Signal Circuit
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. Disconnect the Brake Fluid Level Switch.
3. Disconnect the FCM harness connector.
4. Measure the resistance of the (B20) Brake Fluid Level signal circuit between the Brake Fluid Level Switch harness connector and the FCM harness connector.
  Is the resistance below 5.0 Ohms?
  
  Yes
  - Go To step 5
  No
  - Repair the open in the (B20) Brake Fluid Level Switch signal circuit.
  - Perform ABS VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure .
(Z420) SENSOR GROUND CIRCUIT OPEN

Fig 4: Checking Sensor Ground Circuit
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. Disconnect the Brake Fluid Level Switch harness connector.
3. Reconnect the FCM harness connector.
4. Measure the resistance of the (Z420) Brake Fluid Level Switch ground circuit between the Brake Fluid Level Switch harness connector and ground.
  Is the resistance below 5.0 Ohms?
  
  Yes
  - Replace and program the Front Control Module (FCM) in accordance with the Service Information.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
  No
  - Repair the open in the (Z420) Sensor ground circuit.
  - Perform ABS VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure .