Vehicle Stability Enhancement System Poor Performance

Vehicle Stability Enhancement System Poor Perfomance

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



Circuit/System Description

Proper operation of the Vehicle Stability Enhancement System (VSES) is highly dependent on the ability to apply brake pressure to a selected wheel, through the brake pressure modulator valve (BPMV), as commanded by the electronic brake control module (EBCM). The EBCM may not be able to detect certain mechanical failures that may cause the VSES to perform poorly. This diagnostic procedure is designed to help diagnose concerns of poor vehicle stability that may occur without the presence of any DTCs, by verifying the following.

* The tires are the correct size, properly inflated and in acceptable condition.
* There are no mechanical problems in the steering system.
* There are no mechanical problems in the suspension system.
* There are no mechanical problems in the base brake system.
* There are no mechanical problems in the locking differential or transfer case.
* All of the VSES related hydraulic controls within the BPMV are functioning correctly.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Symptoms - Antilock Brake System (Symptoms - Antilock Brake System)
* Symptoms - Hydraulic Brakes (Symptoms - Hydraulic Brakes)
* Symptoms - Steering Wheel and Column (Hydraulic Power Steering (HPS)) (Symptoms - Steering Wheel and Column (Hydraulic Power Steering (HPS)))
* Symptoms - Suspension General Diagnosis (Suspension General Diagnosis)