viding a more firm, responsive feel to the power
steering system.
With the engine running and the vehicle speed
between 0 kph (0 mph) and approximately 32 kph
(20 mph), minimum steering effort is required.
Between approximately 32 kph (20 mph) and 100
kph (60 mph), power steering effort will gradually
increase based upon vehicle speed. Above approxi-
mately 100 kph (60 mph), maximum steering effort is
required by the speed proportional steering system.
Variable-effort power steering is provided by con-
trolling power steering fluid pressure at the power
steering gear. A solenoid control valve located on the
steering gear (Fig. 1) is used to control power steer-
ing gear return fluid pressure. The pressure is con-
trolled by varying the size of an orifice.
The variable-assist speed-proportional solenoid con-
trol valve is controlled by the Body Control Module
(BCM). The BCM receives the vehicle speed signal
sent from the Powertrain Control Module (PCM).
Upon receiving the vehicle speed signal from the
PCM, the BCM converts that speed signal into an
electrical current usable by the solenoid control valve
for controlling the variable effort of the power steer-
ing system.
SOLENOID CONTROL VALVE
DESCRIPTION
The solenoid control valve is mounted on the speed
proportional power steering gear housing (Fig. 1).
OPERATION
Variable-effort power steering is provided by con-
trolling power steering fluid pressure at the power
steering gear. A solenoid control valve located on the
steering gear (Fig. 1) is used to control power steer-
ing gear return fluid pressure. The pressure is con-
trolled by varying the size of an orifice.
The variable-assist speed-proportional solenoid con-
trol valve is controlled by the Body Control Module
(BCM). The BCM receives the vehicle speed signal
sent from the Powertrain Control Module (PCM).
Upon receiving the vehicle speed signal from the
PCM, the BCM converts that speed signal into an
electrical current usable by the solenoid control valve
for controlling the variable effort of the power steer-
ing system.
The solenoid control valve is a serviceable compo-
nent of the variable-effort, speed-proportional power
steering gear assembly.
DIAGNOSIS AND TESTING
SPEED PROPORTIONAL POWER STEERING
Electronic diagnosis of the variable-effort speed-
proportional power steering system, if suspected of
not functioning properly, is done using the DRB scan
tool. Refer to the Body Diagnostic Manual to properly
test and diagnosis this steering system.
REMOVAL AND INSTALLATION
SPEED PROPORTIONAL POWER STEERING
GEAR
If the variable-effort speed-proportional power
steering gear requires removal from the vehicle, refer
to POWER STEERING GEAR in the REMOVAL
AND INSTALLATION section of POWER STEER-
ING GEAR which can be found elsewhere in this ser-
vice manual group. The only difference in the
removal and installation process is the need to dis-
connect and connect the solenoid control valve wiring
harness connector.
SOLENOID CONTROL VALVE
REMOVE
(1) Disconnect the solenoid control valve electrical
connector from the wiring harness at the power
steering gear end cap below the brake master cylin-
der (Fig. 2).
Fig. 2 Wiring Harness Connection
1 – SPEED PROPORTIONAL STEERING SOLENOID
CONNECTOR
2 – MASTER CYLINDER RESERVOIR
LH STEERING 19 - 43
DESCRIPTION AND OPERATION (Continued)
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