How to Reset the Check Engine Light on a Toyota Tacomaby Jody L. Campbell
The Toyota Tacoma started production in late 1995. Its manufacturing date was synchronized with the implementation of OBD II (on-board diagnostics two), which standardized computer diagnostics for all vehicles in 1996. The check engine light communicates a problem in the emissions system or any other system monitored by sensors that are in direct communication with the engine control module. When one of these components fail, the computer indicates the failure and triggers the check engine light. These failures are called diagnostic trouble codes (DTCs) and should be diagnosed and rectified before attempting to reset the light.
Locate the diagnostic link connector (DLC) in the Toyota Tacoma. It is under the driver's side dashboard between the steering column and the dash. The shape of the connector will match the trapezoidal shape of the plug connection on the OBD II scan tool.
Attach the plug of the OBD II scan tool to the DLC of the Tacoma. Make sure it is plugged in thoroughly.
Place the ignition key into the Tacoma and turn it two clicks to activate the "key-on/engine-off" mode. This mode illuminates the dash and activates the power to the electrical options in the truck without actually starting the engine. It will also provide power to the scan tool from an accessory fuse powered by the battery.
Read the screen of the OBD II scan tool. There are many different kinds with slightly different options, but overall, they function similarly. Scroll buttons and "enter" or "select" keys will help you navigate through the several features the scan tool offers. It is recommended to "read codes" first before resetting, unless you have already made the necessary repair that triggered the check engine light.
Scroll to the "reset" or "erase code" option once the code(s) have been documented, if applicable. Press the "enter"or "select" button to confirm you want to erase the code(s). A few seconds will pass and the OBD II scanner will alert you that the command is being sent to the ECM of the Tacoma. Once the main menu of the scan tool reappears, the check engine light is reset. Be aware that hard codes and even minor codes can and will re-trigger the check engine light if not rectified. Hard codes may re-trigger immediately or may have to endure the IM monitor reset of the ECM. This may take several driving cycles to occur.
Check the status of the check engine light by unplugging the scan tool and then starting the Tacoma. The check engine light should not be illuminated as long as a hard code is not re-triggering the faulty device.
- It is possible to reset the check engine light by disconnecting the negative battery terminal and then stepping on the brake to discharge the memory=holding capacitor in the computer. What happens when you do this -- especially on later-model Tacomas -- is the loss of computer memory and then the computer needs to relearn the information it has stored in all aspects of the truck. The system will relearn, but it will take longer and may affect the performance of the engine until it does so. And if the problem that caused the check engine light to switch on in the first place has not been rectified, it will re-illuminate once the IM monitor resets and fails to communicate to the engine control module.
- The OBD II scan tool is not a tool intended on fixing the problem with the Tacoma -- or any other vehicle for that matter. It is intended to first read the DTC(s) and then communicate the information to make the necessary repairs to restore the system. Just because it can easily erase codes should not imply that the truck is fixed.