Scan Tool Testing and Procedures

TECH 1 DIAGNOSTICS
Tool Required:

TK-0-A TECH 1 Modular Diagnostic

System

The TECH 1, when connected to the ABS DLC, becomes part of the vehicle's electronic system. The TECH 1 can perform the following functions:

^ Display ABS data.

^ Display and clear ABS DTCs.

^ Control ABS components.

^ Perform extensive ABS diagnostics.

^ Provide diagnostic testing for intermittent ABS conditions.

Each test mode has specific diagnosis capabilities which depend upon various keystrokes. In general, five keys control sequencing: "YES," "NO," "EXIT," "~" (up arrow) and " V" (down arrow). The "F0" through "F9" keys select operating modes. perform functions within an operating mode, or enter DTC or model year designations.

In general, the TECH 1 has six test modes for diagnosing the anti lock brake system.

^ MODE FO: DATA LIST - In this test mode, the TECH 1 continuously monitors wheel speed data, brake switch status and other inputs and outputs.

^ MODE F1: CODE HISTORY - In this test mode, DTC history data is displayed. This data includes how many drive cycles since the DTC occurred. along with other ABS information. The first five and last DTC set are included in the ABS history data.

^ MODE F2: TROUBLE CODES - In this test mode, DTCs stored by the EBCM, both current ignition cycle and history, may be displayed or cleared. When a DTC is displayed with a "C," it is an indication that the DTC is current. When a DTC is displayed with an "H," that means that it is a history DTC.

^ MODE F3: SNAPSHOT - In this test mode, the TECH 1 captures ABS data before and after a fault occurrence, manual key press or system malfunction (auto trigger).

^ MODE F4: ABS TESTS - In this test mode, the TECH 1 performs various tests to assist in problem isolation during troubleshooting. For all ABS tests. the TECH I must be powered from the battery using a battery adapter cable.

^ MODE F5: MOTOR REHOME - In this mode. the TECH 1 commands the EBCM to rehome the motors and pistons in the hydraulic modulator assembly. This mode should ALWAYS be used prior to bleeding the brake system.

For more information on TECH 1 diagnostics refer to ABS section of the TECH 1 Operators Manual.

Enhanced Diagnostics

Enhanced diagnostic information, found in the CODE HISTORY function of the TECH 1, is designed to provide the service technician with specific malfunction occurrence information. For each of the first five and the very last DTCs stored. data is stored to identify the specific DTC. the number of occurrences and the number of drive cycles since the malfunction first and last occurred. A normal drive cycle consists of starting the engine, driving the vehicle over 8 km/h (5 mph) and keying down. These first five DTCs are also stored in the order of occurrence. The order in which the first five DTCs occurred can be useful in determining if a previous malfunction is linked to the most recent malfunction, such as an intermittent open in a wheel speed sensor circuit which later becomes completely open. However, if a malfunction is present. the drive cycle counter will increase by turning the ignition switch to "ON" and "LOCK."

During difficult diagnosis situations, this information can be used to identify malfunction occurrence trends. Does the malfunction occur more frequently now than it did during the last customer visit? Did the malfunction only occur once over a large number of driving cycles. indicating an unusual condition present when it occurred? Does the malfunction occur infrequently over a large number of drive cycles. indicating that special diagnosis techniques may be required to identify the source of the malfunction?