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Variable Effort Steering System Buick Riviera VIII

Electronic Steering 6 illustrations ~1143 words

DESCRIPTION & OPERATION

Variable Effort Steering (VES) system may also be referred to as Magna Steer steering system. VES system varies the effort required to turn the steering wheel, providing a firmer steering (road) feel and improved directional stability at higher vehicle speeds.

The VES control module receives battery voltage from instrument panel fuse block IGN 3 fuse while ignition switch is in RUN position. As vehicle speed increases, VES system increases the amount of current to the bi-directional magnetic rotary VES actuator, located in the steering gear assembly. This increases steering effort and improves steering feel.

The VES system consists of a VES control module, VES actuator, steering wheel rotation sensor and Vehicle Speed Sensor (VSS). VES control module receives input from VSS through the Powertrain Control Module (PCM). Based on VSS input, VES control module varies current flow to the VES actuator.

ComponentLocation
Data Link Connector (DLC)Left Side Of Instrument Panel, Behind Sliding Door In Sound Insulator
Fuse BlockLeft Side Of Instrument Panel, Near Door Vent, Behind Cover
PCMRF Side Of Passenger Compartment, Behind Instrument Panel
VES Actuator(2) Inside Steering Gear
VES Control Module(3)
(1) (Scheme 1)-5. (2) For VES actuator connector location (Scheme 4) (3) VES control module is located to left of steering column, on bracket.
(1)(Scheme 1)-5.
(2)For VES actuator connector location (Scheme 4)
(3)VES control module is located to left of steering column, on bracket.

VES SYSTEM ELECTRICAL COMPONENT LOCATIONS (1)

Scheme 1

Scheme 1
Scheme 1

Scheme 2

Scheme 2
Scheme 2

Scheme 3

Scheme 3
Scheme 3

Scheme 4

Scheme 4
Scheme 4

Scheme 5

Scheme 5
Scheme 5

DIAGNOSIS & TESTING

Note. Ensure IGN 3 fuse in instrument panel fuse block is good before continuing. Begin VES system diagnosis with PRE-DIAGNOSTIC INSPECTION procedure.

PRE-DIAGNOSTIC INSPECTION

When checking potential VES system faults, check following before performing CIRCUIT TEST

  1. Check wheel bearings for wear or damage causing wheels to wobble.
  2. Check all VES system wiring harness connectors for proper engagement, loose wires or terminals and/or corrosion.

Check harness routing; pay particular attention to wheel speed sensor wiring harness routing.

  1. Check for proper outer CV joint alignment and operation.
  2. Check for proper tire wear (tread depth).
  3. Always perform «SYSTEM CHECK»(/buick/riviera/viii-1994-1999/remont/electronic-steering/#variable-effort-steering-system__system-check) before diagnosing VES system.

If mechanical component malfunctions are present, or if failure is intermittent and not reproducible, test drive vehicle. Drive vehicle in a normal manner, with normal acceleration, stopping and turning.

If vehicle test drive does not reproduce any failures, perform another test drive with an ABS stop from about 30-50 MPH on surface such as gravel. Perform sudden turns (such as evasive maneuvers). Perform SYSTEM CHECK . If ABS warning light and/or BRAKE warning light illuminates, go to ANTI-LOCK BRAKES article in BRAKES.

SYSTEM CHECK

Start engine. Turn steering wheel left then right. Wheels should turn with minimal effort. Test drive vehicle. Turn steering wheel left then right as vehicle speed increases, effort required to turn steering wheel should increase. If system does not operate as described, go to CIRCUIT TEST .

CIRCUIT TEST

  1. Turn ignition off. Disconnect VES module connector. Turn ignition to RUN position. Using DVOM, measure voltage between ground and Brown wire terminal of VES module connector. If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Brown wire circuit.
  2. Measure voltage between Brown wire terminal and Black wire terminal(s) (2 Black wire terminals on Buick) of VES module connector. If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Black wire circuit.
  3. Turn ignition off. Disconnect VES actuator connector. Turn ignition to RUN position. Measure voltage between Brown and White wire terminals of VES module connector. If battery voltage does not exist, go to next step. If battery voltage exists, repair short to ground in White wire circuit.
  4. Measure voltage between Brown and Gray wire terminals of VES module connector. If battery voltage does not exist, go to next step. If battery voltage exists, repair short to ground in Gray wire circuit.
  5. Measure voltage between White wire terminal and Black wire terminal(s) (2 Black wire terminals on Buick only) of VES module connector. If battery voltage does not exist, go to next step. If battery voltage exists, repair short to ground in White wire circuit.
  6. Measure voltage between Gray wire terminal and Black wire terminal(s) (2 Black wire terminals on Buick) of VES module connector. If battery voltage does not exist, go to next step. If battery voltage exists, repair short to ground in Gray wire circuit.
  7. Turn ignition off. Check continuity of White wire circuit between VES module connector and VES actuator connector. If continuity exists, go to next step. If continuity does not exist, repair open in White wire circuit.
  8. Check continuity of Gray wire circuit between VES module connector and VES actuator connector. If continuity exists, go to next step. If continuity does not exist, repair open in Gray wire circuit.
  9. Raise and support vehicle. Turn ignition on. Place shift lever in Neutral. While rotating a front wheel by hand, measure voltage between Dark Green/White wire terminal and Black wire terminal(s) (2 Black wire terminals on Buick) of VES module connector. If voltage varies from less than one volt to more than 4 volts, go to next step. If voltage is not as specified, repair open in Dark Green/White wire circuit.
  10. Turn ignition off. Measure resistance across VES actuator connector (component side). If resistance is 2-3 ohms, go to next step. If resistance is not as specified, replace steering gear.
  11. Measure resistance between steering gear case and either VES actuator connector (component side) terminal, then the other terminal. If resistance is infinite on both terminals, go to next step. If resistance is not as specified, replace steering gear.
  12. Check all VES system wiring harness connectors for proper engagement, loose wires or terminals and/or corrosion. Check harness routing; pay particular attention to wheel speed sensor wiring harness routing. Repair as necessary. If wiring and connectors are okay, replace VES module.

HYDRAULIC SYSTEM BLEEDING

Note. If air is introduced into hydraulic system during servicing, bleed system. Aerated fluid, which appears Light Tan in color, results in poor steering performance and will cause pump damage. Replace aerated fluid.

  1. Turn ignition off. Raise and support vehicle with front wheels off ground. Turn wheels fully to left. Add power steering fluid to COLD mark on dipstick. Turn wheels from side to side several times, but DO NOT touch steering stops. Add fluid as necessary to maintain level at FULL COLD mark.
  2. Start engine. With engine idling, add fluid as necessary to bring level to FULL COLD mark. Return wheels to center position. Lower vehicle. Continue to run engine for 2-3 minutes to eliminate trapped air and raise fluid to operating temperature.
  3. Road test vehicle. Check for leaks. Ensure fluid level is at FULL HOT mark when fluid is stabilized at operating temperature.

POWER STEERING PUMP BELT

Note. See ADJUSTMENTS in STEERING GEAR - POWER article.

VARIABLE EFFORT STEERING (VES) ACTUATOR

VES actuator is located in steering gear pinon and valve assembly. See STEERING GEAR - POWER article for removal and installation.

Removal & Installation

  1. Disconnect negative battery cable. Remove left instrument panel sound insulator.
  2. Remove VES control module connector. Remove VES control module from bracket by pressing in on retainer and sliding down out of bracket. To install, reverse removal procedure.

Variable Effort Steering (VES) System Wiring Diagram. Scheme 6

Scheme 6: Variable Effort Steering (VES) System Wiring Diagram
Scheme 6: Variable Effort Steering (VES) System Wiring Diagram