Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSJEEP2010GRAND CHEROKEE LIMITED, 5.7 T, 4WDREPAIR AND DIAGNOSISENGINE PERFORMANCEENGINE CONTROL SYSTEMS(FRONT CONTROL MODULE (FCM) - ELECTRICAL DIAGNOSTICS)DTC TROUBLESHOOTINGC1008-BRAKE FLUID LEVEL CIRCUIT HIGHDIAGNOSTIC TEST

2010 Jeep Grand Cherokee Limited, 5.7 T, 4WD

Diagnostic Test

2010 Jeep Grand Cherokee Limited, 5.7 T, 4WDSECTION Diagnostic Test

BRAKE FLUID LEVEL SWITCH SIGNAL VOLTAGE ABOVE 4.9 VOLTS
NOTE: This DTC must be active for the results of this test to be valid.
1. Turn the ignition on.
2. Using 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 For Short To Battery Voltage
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 the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
  No
  - Go to step 3
BRAKE FLUID LEVEL SWITCH INTERNAL FAILURE

Fig 2: Checking Brake Fluid Level Signal And Ground Circuits
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. Connect a jumper wire between the (B20) Brake Fluid Level signal circuit and the (Z387) Brake Fluid Level ground circuit in the Brake Fluid Level Switch harness connector
3. Turn the ignition on.
4. Using 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 the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
  No
  - Go to step 4
(B20) BRAKE FLUID LEVEL SWITCH CIRCUIT OPEN

Fig 3: Checking Brake Fluid Level Switch Circuit For Open
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 Ohms?
  
  Yes
  - Go to step 5
  No
  - Repair the open in the (B20) Brake Fluid Level Switch signal circuit.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
(Z387) SENSOR GROUND CIRCUIT OPEN

Fig 4: Identifying Brake Fluid Level Switch Ground Circuit Connector Terminal
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 (Z387) 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 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 (Z387) Sensor ground circuit.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .

RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.