WTEC III ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL S ECTION 6 — DIAGNOSTIC CODES Copyright © 2001 General Motors Corp. 6–1. DIAGNOSTIC CODE MEMORY Diagnostic codes are logged in a list in memory (sometimes referred to as the queue), listing the most recently occurring code first and logging up to five codes. The codes contained in the list have information recorded as shown in the table below (codes are examples). Access to the code list position, main code, subcode and active indicator is through either the shift selector display or the ATDTTM or Pro-Link® diagnostic tool. Access to ignition cycle counter and event counter information is through the diagnostic tool only.
Further detail on the use of ATDTTM or Pro-Link® 9000 DDR is presented in Appendix N of this manual. Table 6–1. Code List Code List Ignition Cycle Position Main Code Subcode Active Indicator Counter Event Counter d1 21 12 YES 00 10 d2 41 12 YES 00 04 d3 23 12 NO 08 02 d4 34 12 NO 13 01 d5 56 11 NO 22 02 Displayed on shift selector and diagnostic tool YES = LED indicator Not available on shift selector display d = “diagnostic” illuminated The following paragraphs define the different parts of the code list. A. Code List Position. The position which a code occupies in the code list. Positions are displayed as “d1” through “d5” (Code List Position #1 through Code List Position #5). B.
Main Code. The general condition or area of fault detected by the ECU. C. Subcode. The specific area or condition related to the main code in which a fault is detected. D. Active Indicator. Indicates when a diagnostic code is active. The MODE indicator LED on the shift selector is illuminated or the diagnostic tool displays YES. E. Ignition Cycle Counter. Determines when inactive diagnostic codes are automatically cleared from the code list. The counter is increased by one each time a normal ECU power down occurs (ignition turned off). Inactive codes are cleared from the code list after the counter exceeds 50. F. Event Counter. Counts the number of occurrences of a diagnostic code.
If a code is already in the code list and the code is again detected, that code is moved to position d1, the active indicator is turned on, the Ignition Cycle Counter is cleared, and 1 is added to the Event Counter. 6–2. CODE READING AND CODE CLEARING Diagnostic codes can be read and cleared by two methods: by using the ATDTTM or Pro-Link® 9000 diagnostic tool or by entering the diagnostic display mode and using the shift selector display. The use of the ATDTTM or Pro-Link® 9000 diagnostic tool is described in the instruction manual furnished with each tool and briefly in Appendix N of this manual.
The method of reading and clearing codes described in this section refers to entering the diagnostic display mode by the proper button movements on the shift selector. Table 6–1. Code List Code List Position Main Code Subcode Active Indicator Ignition Cycle Counter Event Counter d1 21 12 YES 00 10 d2 41 12 YES 00 04 d3 23 12 NO 08 02 d4 34 12 NO 13 01 d5 56 11 NO 22 02 Displayed on shift selector and diagnostic tool d = “diagnostic” YES = LED indicator illuminated Not available on shift selector display The following paragraphs define the different parts of the code list. A. Code List Position. The position which a code occupies in the code list.
Positions are displayed as “d1” through “d5” (Code List Position #1 through Code List Position #5). B. Main Code. The general condition or area of fault detected by the ECU. C. Subcode. The specific area or condition related to the main code in which a fault is detected. D. Active Indicator. Indicates when a diagnostic code is active. The MODE indicator LED on the shift selector is illuminated or the diagnostic tool displays YES. E. Ignition Cycle Counter. Determines when inactive diagnostic codes are automatically cleared from the code list. The counter is increased by one each time a normal ECU power down occurs (ignition turned off).
Inactive codes are cleared from the code list after the counter exceeds 50. F. Event Counter. Counts the number of occurrences of a diagnostic code. If a code is already in the code list and the code is again detected, that code is moved to position d1, the active indicator is turned on, the Ignition Cycle Counter is cleared, and 1 is added to the Event Counter. 6–2. CODE READING AND CODE CLEARING Diagnostic codes can be read and cleared by two methods: by using the ATDTTM or Pro-Link® 9000 diagnostic tool or by entering the diagnostic display mode and using the shift selector display.
The use of the ATDTTM or Pro-Link® 9000 diagnostic tool is described in the instruction manual furnished with each tool and briefly in Appendix N of this manual. The method of reading and clearing codes described in this section refers to entering the diagnostic display mode by the proper button movements on the shift selector.