Section 5 – GM Diagnostics

✓If the Scan Tool displays an Error Message, make sure the cables and adapters are securely attached and the ignition key is ON. Cycle the ignition key to OFF for 10 seconds, then ON. Attempt the test selected again. If the problem remains, refer to “Error Messages” on page 9-2.

GM HISTORIC (OBD I) DIAGNOSTICS

✓Some 1994 and 1995 vehicles use the 16-pin OBD II connector, but are not OBD II compliant. They still use the OBD I application software. Refer to “Appendix A - Data Link Connectors".

Manual Info

The Manual Info function instructs the user what section of the manual to use. This section covers GM Historic (OBD I) Diagnostics.

Read Codes

The Read Codes function is used to retrieve all stored Diagnostic Trouble

 

Codes (DTCs) from the control module(s). This can be performed with key ON

5

engine OFF (KOEO) or key ON engine RUNNING (KOER). Two types of codes

were used by GM in the Historic System: Current codes and History codes. Prior to 1986, all codes were referred as Current Codes. From 1986 through 1995, both codes were used as the PCM was able to differentiate them.

The tool automatically displays the type of codes that pertain to the vehicle under test. The DTC types are defined as follows:

•History Codes — intermittent codes placed in the vehicle’s memory when the trouble originally occurred, and will remain there even if the trouble has been corrected. If no trouble after 50 engine warm-up cycles, the DTC erases.

•Current Codes — codes transmitted through the PCM’s data stream when a trouble condition is active and cannot be erased. The problem must be repaired to remove the DTC.

✓On some vehicles, all codes are Current Codes, because the PCM cannot distinguish Current Codes from History Codes. The only way to determine this is to erase the code and then drive the vehicle to see if the code returns.

Perform the following:

1)Set Parking Brake

2)Turn Key On-Engine Off or Running.

3)Put Transmission In Park Or Neutral.

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Actron 9640 user manual GM Historic OBD I Diagnostics, Manual Info, Read Codes
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9640 specifications

The Actron 9640 is a distinguished automotive diagnostic tool that has garnered attention for its versatility and user-friendly design. Designed for professional mechanics and DIY enthusiasts alike, the Actron 9640 stands out for its comprehensive features and advanced technologies that simplify vehicle diagnostics.

One of the main features of the Actron 9640 is its ability to read and erase diagnostic trouble codes (DTCs) for a wide variety of vehicles. This tool supports OBD II protocols, allowing it to communicate with a vast array of vehicles produced after 1996. The device provides clear, detailed descriptions of any trouble codes, enabling users to quickly identify and address issues. This is vital for efficient troubleshooting and ensures that users can make informed decisions about repairs.

Another significant advantage of the Actron 9640 is its built-in memory. The device can store code definitions and repair solutions for easy reference during diagnostics. Additionally, it features a robust data logging capability, allowing users to capture live data in real-time, which is essential for performing thorough diagnostic evaluations. This functionality helps in monitoring engine performance, thereby assisting in pinpointing issues that may not always trigger a check engine light.

The Actron 9640 also incorporates a user-friendly interface, equipped with a large LCD display that presents information in an easy-to-read format. Its intuitive navigation and menu options cater to users of varying expertise, making it accessible to beginners while still offering the depth of features that seasoned professionals rely on.

In terms of connectivity, the Actron 9640 is designed to be compatible with various vehicles, supporting multiple protocols beyond OBD II, including CAN, J1850, and ISO9141. This broad networking capability ensures that the device can diagnose problems across different car brands and models.

Built with durability in mind, the device features a robust housing that can withstand the rigors of a workshop environment. The ergonomic design ensures a comfortable grip during use, making it practical for extended periods of diagnostics.

Overall, the Actron 9640 combines advanced features, comprehensive functionality, and ease of use, making it an excellent choice for anyone looking to conduct reliable automotive diagnostics. Whether you're a professional mechanic or a casual car owner, the Actron 9640 can help you maintain your vehicle's performance effectively.
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