The instrument panel cluster (IPC) supplies 12 volts to the supplemental brake assist (SBA) module via the SBA signal circuit. The SBA toggles this voltage to ground to produce a valid SBA signal.
This diagnostic procedure supports the following DTC:
DTC C0136 Base Brake System Pressure Circuit
The ignition is ON.
| • | The IPC does not receive a valid health signal from the SBA for 5 consecutive ignition cycles. | 
| • | The SBA is producing a SBA signal indicating a system failure. | 
The service brake booster message is displayed.
The scan tool is used to clear the DTC.
Step  | Action  | Yes  | No  | 
|---|---|---|---|
1  | Did you perform the Diagnostic System Check - Vehicle?  | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information  |