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.
Diagnostic Test
- READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR THE DTC TO RETURN
- With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
- With the scan tool, run a vehicle Scan Report, or record the Environmental Data related to the DTCs.
- With the scan tool, erase all DTCs.
- Turn the ignition off for a minimum of 10.0 seconds.
- Turn the ignition on.
- Using the recorded Environmental Data and the When Monitored Conditions above, operate the vehicle in the conditions that set the DTC.
- With the scan tool, read Body Control Module (BCM) DTCs.
Did the DTC return?
Yes
- Go To 2
No
- Perform the appropriate INTERMITTENT CONDITION diagnostic procedure. Refer to TESTING FOR AN INTERMITTENT CONDITION .
- DISCONNECT THE BRAKE FLUID LEVEL SENSOR HARNESS CONNECTOR - CONNECT A FUSED JUMPER WIRE BETWEEN THE SENSOR GROUND CIRCUIT AND THE (B20) BRAKE FLUID LEVEL SIGNAL CIRCUIT - CHECK THE BCM DATA
- Turn the ignition off.
- Disconnect the component harness connector(s) for the circuit being tested.
- Connect a fused jumper wire between the ground circuit and the circuit being tested at the component harness connector. Note: Use the wiring diagram as a guide to follow the path of the circuit.
- Turn the ignition on.
- With the scan tool, read the Brake Fluid Level data.
Does the Brake Fluid Level data display Low?
Yes
- Replace the Brake Fluid Level Switch in accordance with the Service Information. Refer to SWITCH, BRAKE FLUID LEVEL, REMOVAL AND INSTALLATION .
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
No
- Go To 3
- CHECK THE SENSOR GROUND CIRCUIT FOR AN OPEN OR HIGH RESISTANCE BY LOAD TESTING THE CIRCUIT
- Turn the ignition off.
- Connect the positive lead of the load test tool to a 12 volt circuit at the component harness connector.
- Connect the negative lead of the load test tool to the ground circuit at the component harness connector (A). Note: refer to the diagram below.
- The bulb on the load test tool should be illuminated and bright if there is no resistance in the circuitry.NOTE:
Note: Why load test a circuit? A load test is used to determine if a circuit is capable of carrying the amperage needed to perform properly. The 3156 Bulb in the load tool illustrated, is a simple but effective method of testing circuit functionality. A 3156 Bulb has approximately 6.0 Ohms of resistance when the bulb is powered and draws approximately 2.0 amps of current. Read the CIRCUIT VOLTAGE DROP AND LOAD TESTING PROCEDURES for information on building a simple load test tool and for additional load testing information and alternative methods of load testing or voltage drop testing a circuit. Refer to CIRCUIT LOAD TESTING PROCEDURES .
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.