Test E Valve Control

Antilock Brakes And Traction Control Wiring Diagram:

E: Valve Control Test:

OPERATION:

Inlet/Outlet Valves
Voltage is applied to the normally open inlet valves whenever the main relay is energized. An Inlet valve closes when the EBCM/EBTCM supplies a ground path at the inlet valve control terminal. The EBCM/EBTCM closes an inlet valve for short periods to maintain (hold) or reduce pressure at a particular wheel.

The normally closed outlet valves operate similarly to the inlet valves, except that when the ESCM/EBTCM grounds an outlet valve, the valve opens instead of closes. The EBCM/EBTCM opens an outlet valve for short periods to reduce pressure at a particular wheel.

Valve Modes
The pressure increase position is the operating valve position for normal (non-ABS) braking and traction control mode (when equipped). The EBCM/EBTCM does not energize either valve, leaving the inlet valve open and the outlet valve closed.

The pressure hold position occurs when the EBCM/EBTCM first notices an abnormal hydraulic pressure increase. This signifies an impending wheel lockup condition. The EBCM/EBTCM closes the corresponding inlet valve to avoid any additional hydraulic pressure increase (avoiding an ABS braking condition).

During a wheel lockup condition, the EBCM/EBTCM closes the inlet valve while pulsing open the outlet valve. This decreases hydraulic pressure at a specific wheel without decreasing overall system pressure. The reduced hydraulic pressure allows greater wheel spin, eliminating the wheel lockup condition.

DTC 41, 42, 45, 46, 51, 52, 55, or 56 sets when the (EBCM/EBTCM) detects an open or short to ground in the respective inlet or outlet valve circuit.

POSSIBLE CAUSES:
Open in CKT 857, 858, 859, 861, 862, 863, 1290 or 1291.
Short to ground in CKT 857, 858, 859, 861, 862, 863, 1290 or 1291.