System Test
SYSTEM TESTThe system test consists of a stationary test and a road test.
The stationary test monitors operation of the AW-4 transmission system for the presence of data, current solenoid faults, switch faults, correct Transmission Control Module (TCM) design and calibration levels, and proper functioning of the TCM. The Technician is directed by the DRBII to perform several mechanical functions, including:
- Selecting gears
- Depressing the brake pedal
- Operating the mode select switch
- Depressing the accelerator pedal
Seven asterisks (*******) are displayed on the DRB-II corresponding to throttle positions 1 through 7. By depressing the accelerator, the TPS sweeps through the entire range of positions required by the TCM. A corresponding asterisk will be cleared from the display as each of the throttle positions are sensed by the TCM. Several attempts may be required to clear all of the asterisks from the display, depending on how fast the accelerator pedal is depressed.
The DRB-II indicates whether or not a requested action has been seen by the TCM. If the Technician is requested to perform a particular operation, and the TCM does not acknowledge the action, pressing ENTER allows the Technician to continue testing.
During the road test portion of the system test, all solenoids, and the speed sensor are tested. The Technician is directed to accelerate to 55 mph at light throttle to ensure that the transmission is shifted through all gears and thereby all three solenoids are tested. A test site should be selected where the vehicle can be accelerated slowly and evenly to a speed sufficient to allow all gear transitions without downshifting, and without braking during the test. A fault sensed with any solenoid or the speed sensor will be displayed.
NOTE: If a fault is sensed by the TCM, the control logic forces a specific solenoid (gear) configuration depending on the solenoid faulted. Because transmission faults are sensed and displayed one at a time, multiple faults must be identified by retesting.