The ABS relay supplies battery voltage to 6 valve solenoids. The electronic brake control module (EBCM) microprocessor applies the grounds needed to activate each solenoid. The low side of each solenoid coil has a feedback circuit to the EBCM microprocessor. When a solenoid is commanded OFF, the feedback voltage is high. When a solenoid is commanded ON, the feedback voltage is low.
• | The ignition is ON. |
• | The vehicle speed is greater than 6 km/h (4 mph). |
The EBCM detects an internal malfunction.
• | The EBCM disables the ABS. |
• | The ABS indicator turns ON. |
The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.
An intermittent open/shorted solenoid DTC can be set by several different internal EBCM problems. Replace the EBCM if an open/shorted solenoid DTC continues to set intermittently.
Step | Action | Yes | No |
---|---|---|---|
1 | Did you perform the ABS Diagnostic System Check? | Go to Step 2 | |
2 |
Does the DTC set? | Go to Step 3 | Go to Diagnostic Aids |
3 |
Important: Following EBCM replacement, use the scan tool to perform the Tire Size Calibration procedure and the Trim Level Calibration procedure, if applicable. Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Did you complete the replacement? | Go to Step 4 | -- |
4 |
Does the DTC reset? | Go to Step 3 | System OK |
The EBCM supplies approximately 12 volts through an internal resistor to the powertrain control module (PCM) on the delivered torque signal circuit. The PCM toggles this voltage to ground in order to create the delivered torque signal at the EBCM. A signal with a frequency of 128 Hz +/- 5 percent and a duty cycle of 25-95 percent is a valid delivered torque signal. The percentage of duty cycle is proportionate to the percentage of delivered engine torque.
• | The ignition is ON. |
• | The engine is running at a speed greater than 450 RPM for 1 second. |
The EBCM receives an invalid delivered torque signal for 300 milliseconds.
• | The EBCM disables the VSES. |
• | Engine torque reduction is disabled. |
• | The traction off indicator turns ON. |
• | The message center displays the service stability system message. |
The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.
Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to the following:
The numbers below refer to the step numbers on the diagnostic table.
This step tests for voltage supplied to the PCM from the EBCM.
This step tests for a shorted resistor in the EBCM or a short to voltage within the circuit, by verifying that a large voltage drop occurs in the circuit when the test lamp is placed in parallel with the DMM. The PCM may be damaged if either of these conditions is present.
Step | Action | Values | Yes | No |
---|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Antilock Brake System Connector End Views Connector End View Reference: Powertrain Control Module Connector End Views in Engine Controls - 4.8L, 5.3L and 6.0L | ||||
1 | Did you performs the ABS Diagnostic System Check? | -- | Go to Step 2 | |
2 |
Does the DTC set? | -- | Go to Step 3 | Go to Diagnostic Aids |
Does the voltage measure greater than the specified value? | 10 V | Go to Step 4 | Go to Step 5 | |
Does the voltage measure less than the specified value? | 0.15 V | Go to Step 6 | Go to Step 10 | |
5 | Test the delivered torque signal circuit for an open, or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 8 |
6 |
Does the scan tool display a duty cycle of the delivered torque signal within the specified range? | 25-95% | Go to Step 7 | Go to Step 11 |
7 |
Does the Hz frequency of the delivered torque signal measure within the specified range? | 121-134 Hz | Go to Step 9 | Go to Step 12 |
8 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
9 |
Important: Following EBCM replacement, perform the set-up procedure for the EBCM and perform the Yaw Rate Reference Table Reset Procedure. Use the scan tool to perform the Tire Size Calibration procedure. Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
10 | Test the delivered torque signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 |
11 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 |
12 |
Important: Perform the setup procedure for the PCM. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 4.8L, 5.3L, and 6.0L. Did you complete the replacement? | -- | Go to Step 13 | -- |
13 |
Does the DTC reset? | -- | Go to Step 3 | System OK |