Pinpoint Test A: Steering Has Lack of Assist or Inconsistent Assist - Vehicles with Vacuum Boost

Steering System

Pinpoint Test A: Steering Has Lack of Assist or Inconsistent Assist - Vehicles with Vacuum Boost

NOTE: Hard steering or lack of assist is experienced when the steering wheel effort exceeds specifications. Hard steering can remain constant through the full turn, occur near the end of a turn or differ right to left. It is important to know the difference between hard steering/lack of assist and poor returnability/sticky steering.

This pinpoint test is intended to diagnose the following:

- Steering gear

- Power steering pump

- Power steering hoses

PINPOINT TEST A : STEERING HAS LACK OF ASSIST OR INCONSISTENT ASSIST - VEHICLES WITH VACUUM BOOST

A1 CHECK THE STEERING ASSIST WITH THE ENGINE RPM RAISED

- NOTICE: Do not hold the steering wheel at the stops for an extended amount of time. Damage to the power steering pump can occur.

Set the engine at 2,100 rpm and turn the steering wheel fully to the left and right.


Is steering assist normal with the engine rpm raised?

Yes
INSTALL a new power steering pump.

No
GO to A2.

A2 CHECK FOR A CHANGE OF ASSIST ON LEFT AND RIGHT TURNS

- With the engine at idle, turn the steering wheel fully to the left and to the right.

Does the steering assist change when turning from right to left?

Yes
INSTALL a new steering gear.

No
GO to A3.

A3 CHECK THE STEERING LINES AND HOSES FOR RESTRICTIONS

- Inspect the steering lines and hoses for damage, kinks or restrictions.

Are the steering lines or hoses damaged, kinked or restricted?

Yes
INSTALL new lines or hoses as necessary.

No
GO to A4.

A4 MONITOR THE ENGINE RPM CHANGES

NOTICE: Do not hold the steering wheel at the stops for an extended amount of time. Damage to the power steering pump can occur.

NOTE: Make sure that the vehicle is on a flat, dry surface, all accessories are in the OFF position and that the steering system is at normal operating temperature.

- Connect the scan tool.

- Start the engine.

- With the engine at idle, raise the power steering fluid temperature to 74-80°C (165-176°F) by rotating the steering wheel fully to the left and right several times.

- While monitoring the engine rpm with the scan tool, turn the steering wheel quickly to the left stop position and then to the right stop position.

- Note the engine rpm during the turns.

Does the engine rpm change (even temporarily) more than 30 rpm when turning the steering wheel?

Yes
INSTALL a new steering gear.

No
INSTALL a new power steering pump.