Tech-1 Diagnostics
TECH-1 DIAGNOSTICS
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 antilock brake system.
MODE F0: 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: MISC. TESTS - In this test mode, the TECH-1 performs various tests to assist in problem isolation during troubleshooting.
NOTE: When ABS MISC TEST is performed, the following description appears of the display.
"For all ABS tests the TECH-1 must be powered directly from the battery using a battery adapter cable."
However, when ABS MISC TEST Is performed with this model, it is not necessary to use the battery adapter cable because power is supplied to TECH-1 by connecting TECH-1 DLC to DLC on the vehicle side.
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.
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?
If, for example, a malfunction occurred one out of 20 drive cycles, the malfunction is intermittent and has not recurred for 19 drive cycles. This malfunction may be difficult or impossible to duplicate and may have been caused by a severe vehicle impact (large pot hole, speed bump at high speed, etc.) that momentarily opened an electrical connector or caused unusual vehicle suspension movement. Problem resolution is unlikely, and the problem may never recur (check diagnostic aids provided for that DTC). If, for example, the malfunction occurred three out of 15 drive cycles, the odds of finding the cause are still not good, but you know how often it occurs and you can determine whether or not the malfunction is becoming more frequent based on an additional or past customer visit if the source of the problem cannot or could not be found. If the malfunction occurred 10 out of 20 drive cycles, the odds of finding the cause are very good.
Using the additional malfunction data, you can also determine if a malfunction is randomly intermittent or if it has not recurred for long periods of time due to weather changes or a repair prior to this visit. Say a DTC occurred 10 out of 20 drive cycles but has not recurred for 10 drive cycles. This means the malfunction occurred 10 out 10 drive cycles but has not reoccurred since. A significant environmental change or repair may have occurred 10 drive cycles ago. A repair may not be necessary if customer information can confirm a recent repair. If no repair was made, the service technician can focus on diagnosis techniques used to locate difficult-to-recreate problems.