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How to Use the Actron Cp9135 Auto Code Reader

by Jody L. Campbell

Although the Actron CP9135 is no longer in production, it is still a widely available code reader in the automotive repair and parts industry. The CP9135 is OBD II compliant. This was the second phase of automobile on-board diagnostics that standardized plug connections and tools to read trouble codes on all vehicles manufactured from 1996 and beyond. While some manufacturers began complying to OBD II as early as 1994 (for 1995 models), many were still installing first-phase on-board diagnostics (until the mandated date) making the plug connections and code readers/scan tools needed vehicle specific.

Locate the data/diagnostic link connector (DLC) on the vehicle. Refer to the vehicle's owner's manual for the location of the DLC, if necessary. The most common location for the DLC is under the driver's side dashboard near the steering column. Inspect the plug of the CP9135 in order to look for a plug with the same trapezoidal shape. Some DLCs (not all) may feature a cover on them that requires removal of the cover in order to plug the code reader into them. Other places for DLCs (much less common) may be on the passenger side lower dash, behind the ashtray (some earlier Honda models) or in the center console (very rare).

Plug the CP9135 code reader into the DLC. The auxiliary battery power of the vehicle will automatically provide power to the code reader, which eliminates having to turn on a power button on the unit.

Turn the ignition key to the "On" position without starting the engine. This will set up reading any diagnostic trouble codes (DTCs) that have triggered the malfunction indicator lamp (also known as the check engine light).

Follow the on-screen LCD menu display on the face of the CP9135. Use the buttons on the face of the code reader below the screen to perform the task intended. The main menu will display options "1" through "5:" 1, Read codes; 2, Erase codes (the unit also features an Erase button which can eliminate this option if desired); 3, MIL status; 4, I/M (inspection and maintenance monitors); and 5. Tool setup/test. The tool setup/test option will feature an additional "1" through "5" options.

Press the "Enter" button (lower right-hand button on the unit face) with the menu on option 1 (read codes) to determine any DTCs that may have triggered the MIL. A brief description of the DTC(s) will appear once the CP9135 has communicated with the vehicle's computer. Also, press the "Enter" button when on any other option ("1" through "5") to activate the desired option.

Scroll down ("No" button) to the other four options below the "Read codes" if desired. Option "2" will erase the DTC(s) or the "Erase" button (top right on the unit face) if desired. Be aware that if the DTCs displayed are not corrected or "hard codes" (immediate trouble codes), the MIL will not remain out once the computer of the vehicle has reset and the sensors and circuits have recommunicated to the computer. The circuits and sensors involved with the recommunication to the computer are also known as the I/M monitors. These may take as long as several driving cycles to recommunicate, and once they have, they will either become "ready" or will re-trigger the MIL on the instrument panel.

Use the "Yes" and "No" buttons (on the center of the unit face) to scroll up or down between desired options. Also, use them to answer "yes" or "no" to questions the on-screen display may ask. When erasing a DTC, for example, the CP9135 will offer the option "are you sure you want to erase the DTCs?" Enter "yes" or "no" as desired.

Press the "Back" button whenever going back to a previous option is desired.

Scroll to option "3" (MIL status), and hit the "Enter" button to find out the current MIL status of the vehicle. If the I/M monitors have not reset, the MIL status will inform the user the status is not ready.

Scroll to option "4" (I/M monitors) and press the "Enter" button to discover which I/M monitors are still not in "ready" mode yet. This option works best with the vehicle running and performing drive cycles in order to view the progress of the I/M monitors (may take several drive cycles, as explained in Step 6).

Scroll to option "5" (Tool setup/test), and press the "Enter" button to scroll through the additional options. These options are specifically for the functionality and troubleshooting of the CP9135 unit: 1, "Adjust contrast" changes the contrast of the on-screen menu using the "Yes" and "No" buttons to scroll; 2, "Display test" displays LCD display of the on-screen menu; 3, "Keyboard test" performs a test on the keyboard buttons on the unit to ensure they're functioning correctly; 4, "Memory test" check the memory of the unit to ensure it is functioning properly; 5, "SW ID" (software identification) is used when contacting customer support for the functionality of the unit is required.

About the Author

Jody L. Campbell spent over 15 years as both a manager and an under-car specialist in the automotive repair industry. Prior to that, he managed two different restaurants for over 15 years. Campbell began his professional writing career in 2004 with the publication of his first book.

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