Special Functions

In this test mode, the scan tool can be used to perform functional tests on the ABS/TCS which help verify proper operation. Malfunction conditions can be further identified by testing and observing the test results. DTCs must be cleared before any tests in Special Functions can be performed. The Special Functions are listed below:
- Automated Test
- Solenoid Tests (for all inlet and outlet solenoid valves)
- Lamp Test The Special Functions are detailed as Follows:

LAMP TEST
This test allows activation of the following indicators:
- ABS Telltale
- Low Traction Telltale
- ETS Switch LED
The Lamp Test aids in diagnosing indicator malfunctions. The test allows the operator to flash the indicator on and off manually.

AUTOMATED TEST
The Automated Test cycles each valve solenoid and the pump motor (as well as the necessary relays) to check component operation. If a malfunction is detected, the EBTCM will set DTC(s), which will be displayed upon completion of the test.Perform the test as follows:
1. Ignition OFF
2. Install the scan tool.
3. Turn ignition to RUN.
4. Select the scan tool's Special Functions.
5. Select the Automated Test.
6. Run the Automated Test.
7. Note any DTCs set.

SOLENOID TESTS (INLET VALVES)
The Solenoid Test for inlet valves activates the selected wheel circuit inlet valve placing it in the pressure hold position. When in the pressure hold position, the valve will not allow master cylinder pressure to be delivered to the hydraulic wheel circuit. This is done under ABS operating conditions because the EBTCM has determined that the wheel is moving too slowly, so it holds additional master cylinder pressure from it in an attempt to allow it to rotate at an appropriate speed. The Scan tool commands the valve to close, which should allow the technician to spin the wheel even though an assistant is applying pressure to the brake pedal.
Perform the test as follows:
1. Ignition OFF
2. Install the Scan tool.
3. Turn ignition to RUN.
4. Raise vehicle such that wheels are about six inches off the floor with the transmission in neutral.
5. Select the scan tool's Special Functions.
6. Select Solenoid Test. Have an assistant command Hold Pressure with the scan tool.
7. Have the assistant press and hold the brake pedal.
8. Attempt to move the wheel being tested by hand; it should move even though the assistant is applying pressure to the brake pedal. The wheels may be difficult to turn by hand, but can be moved if the system is working properly.

SOLENOID TESTS (OUTLET VALVES)
The Solenoid Test for outlet valves activates the selected hydraulic wheel circuit valves, placing them in the pressure release position. When in the pressure release position, the valve will allow wheel caliper pressure to be returned to the master cylinder circuit. This is done under ABS operating conditions because the EBTCM has determined that the wheel is moving too slowly, and holding additional master cylinder pressure from it has not allowed it to rotate at an appropriate speed. The scan tool commands the valve to these positions which should allow the technician to spin the wheel even though an assistant is applying pressure to the brake pedal.
Perform the test as follows:
1. Ignition OFF
2. Install the Scan tool.
3. Turn ignition to RUN.
4. Raise vehicle such that wheels are about six inches off the floor with the transmission in neutral.
5. Have an assistant press and hold the brake pedal.
6. Select Solenoid Test. Have an assistant command Release Pressure with the scan tool.
7. Attempt to move the wheel being tested by hand; it should move even though the assistant is applying pressure to the brake pedal. The wheels may be difficult to turn by hand, but can be moved if the system is working properly.