GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 Sonoma Pickup - 4WD 🢒 Suspension 🢒 Suspension General Diagnosis 🢒 Vehicle Leads/Pulls

Step

Action

Yes

No

DEFINITION: Lead/pull is the deviation of the vehicle from a straight path on a level road with no pressure on the steering wheel. Use the lead/pull correction table in order to verify that improper wheel alignment or worn components are not mistaken for tire lead.

1

Did you review the General Description and perform the necessary inspections?

Go to Step 2

Go to Symptoms - Suspension General Diagnosis

2

Road test the vehicle in order to verify the complaint. Select a smooth level surface to perform the test.

Does the vehicle operate normally?

System OK

Go to Step 3

3

Inspect the tire/wheel assemblies for the following conditions:

    • Correct tire pressure
        Refer to Tire Inflation Pressure Specifications in Maintenance and Lubrication.
    • Correct tire size
        Refer to Vehicle Certification Label in General Information.

Do any of the above conditions apply?

Go to Step 4

Go to Step 5

4

Repair/replace the tire/wheel assemblies as necessary.

Did you complete the repair?

Go to Step 15

--

5

Inspect the front/rear suspensions for the following conditions:

    • Vehicle trim height
        Refer to Trim Height Inspection .
    • Excessive wear or loose components.
    • Excessive wheel bearing play
        Refer to Wheel Bearings Diagnosis .

Do any of the above conditions apply?

Go to Step 6

Go to Step 7

6

Repair/replace components as necessary.

    • Tighten components to specifications. Refer to Fastener Tightening Specifications in Front Suspension or Fastener Tightening Specifications in Rear Suspension.
    • Adjust or replace the wheel bearings . Refer to the appropriate procedure:
       -  Wheel Bearing Adjustment in Front Suspension
       -  Front Wheel Hub, Bearing, and Seal Replacement in Front Suspension

Did you complete the repair?

Go to Step 15

--

7

Inspect the brake system for brake drag. Refer to Diagnostic Starting Point - Hydraulic Brakes in Hydraulic Brakes.

Do any of the above conditions apply?

Go to Step 8

Go to Step 9

8

Repair/replace components as necessary.

Did you complete the repair?

Go to Step 15

--

9

Inspect the steering gear valve for an unbalance.

If this is the cause, steering effort will be very light in the direction of the lead and effort will be heavy in the opposite direction with the vehicle parked on a smooth level surface.

Does the above condition apply?

Go to Step 10

Go to Step 11

10

Replace the steering gear valve. Refer to Steering Gear Valve Replacement - Off Vehicle in Power Steering System.

Did you complete the repair?

Go to Step 15

--

11

Inspect the wheel alignment. Refer to Wheel Alignment Measurement in Wheel Alignment.

Is the wheel alignment in specifications?

Go to Step 13

Go to Step 12

12

Adjust alignment to specifications. Refer to Wheel Alignment Measurement in Wheel Alignment.

Did you complete the repair?

Go to Step 15

--

13
  1. Cross-switch the front tire/wheel assemblies.
  2. Road test the vehicle on a smooth level surface.

Does the vehicle still lead/pull?

Go to Step 14

System OK

14

Does the vehicle lead/pull in the opposite direction?

Go to Radial Tire Lead/Pull Correction in Tires and Wheels

Go to Step 15

15

Operate the vehicle in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3