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Toyota Tacoma OBDII Not Communicating with Smog Machine

My 1998 Toyota Tacoma failed the smog test due to the OBD not communicating with smog test system. Where should I start looking for the problem? Is this something I might be able to fix myself?
Answer:

There could be a few reasons your Toyota Tacoma is having problems communicating with the smog testing equipment. The simplest problem could be loose wiring within the OBD II data link connector and/or possibly a blown Data Link Connector fuse. The most complicated fault could be a problem with the Engine Control Computer (ECU); rare fault specially if the check engine light is not illuminated. If you can purchase an inexpensive Trouble Code reader, go ahead and try connecting to your Toyota Tacoma's ECU via the OBD II DLC at home. If the scanner lights up (using power from the truck and not from a battery inside the scanner) as it's connected to your truck this indicates there is power and ground at the connector and the problem is more then likey with the signal wire between the OBD II connector and the ECU. If the scanner does not light up, this might indicate either a loose or disconnected power or ground wire at the connector, and even the possibility of a shorted fuse. Check your Toyota Tacoma fuse box for a fuse labeled DLC (Data Link Connector). Ensure it is not burnt. posted by SmogTips Support

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