Electromagnetic Interference - GMC chervolet camaro 1999 Service Manual

5-128 Antilock Brake System
Solenoid Tests (Inlet Valves)
The Solenoid Test for inlet valves activates 1he
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 EBCM/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 6 inches
off the floor with the transmission in neutral.
5. Select the scan tool's Special Functions.
6. Select Valve 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 sho.uld 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 Tests for the outlet valves activates the
selected hydraulic wheel circuit valves, placing
them in the pressure reduce position. When in the
pressure reduce 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 EBCM/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 valves 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 6 inches
off the floor with the transmission in neutral.
5. Have an assistant press and hold the brake pedal.
6. Select the scan tools Special Functions.
7. Select Valve Solenoid Test. Have the assistant
command Release Pressure with the scan tool.
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.
Brakes
Traction Control System Test
This test runs the pump motor and appropriate
solenoid valves to apply fluid pressure to the rear
wheel circuits.
Perform the test as follows (this test does NOT require
an assistant):
1. Ignition OFF.
2. Install the scan tool.
3. Turn ignition to RUN.
4. Raise vehicle so that wheels are about 6 inches
off the floor with the transmission in neutral.
5. Select the scan tools Special Functions.
6. Select TCS Test.
7. Command the TCS Test on with the scan 1001.
The pump motor will turn on for approximately
25 seconds.
8. Attempt to move each rear wheel by hand, they
should not move, due to the pump motor running
and applying pressure to the rear wheels.
TP Sensor Replacement
This procedure must be run anytime the TP sensor is
replaced on a vehicle that has Traction Control
(RPO NW9). The TP sensor replacement allows the
Accelerator and Servo Control Module (ASM) to
relearn the new ,:P sensor position.
1. Ignition OFF.
2. Install the scan tool.
3. Turn ignition to RUN.
4. Select the scan tools Special Functions.
5. Select TP Sensor Replacement.
6. Follow the scan tool menus until the procedure is
completed.
Electromagnetic Interference
Due to the sensitivity of electronics to Electromagnetic
Interference (EMI), the following checks should be
performed if an intermittent malfunction is suspected.
1. Check for proper installation of wiring harnesses
resulting from add-on options.
2. Check for proper routing of front wheel speed
sensor Wiring near spark plug wires.
(
(