If the Check Engine light on your Ford F-150 pick-up won't turn off, you might need to reset the codes on the OBD II (On-Board Diagnostics II) computer. For U.S. vehicles made prior to 1996, when OBD II became the industry standard, a little know-how is required to reset the codes. Ford integrated OBD I computers on the F-150 engine as far back as the mid-1980s, so here's how to reset/clear the codes.
Under the hood of your Ford F-150, loosen the black (negative) battery terminal clamp with a hand wrench and wiggle the clamp off the terminal.
Wait five minutes.
Reconnect the clamp to the battery post and tighten the clamp with a hand wrench.
Start the Ford F-150 to ensure the check engine light is no longer illuminated.
Locate the diagnostic link connector (DLC) beneath the driver's side dashboard.
Plug the pocket scanner into the DLC and turn the ignition key two clicks to the key on/engine off position.
Follow the procedures for the pocket scanner to erase the codes. There are now many affordable pockets scanners on the market that employ slightly different procedures. Most employ a scroll button or two that will allow you to position the on-screen cursor to a desired selection. Once you've scrolled to the erase code selection, pressing the enter key is all that's required. There may be a few seconds while the scanner sends the command to the F-150's computer.
Start the engine to ensure the malfunction indicator light is no longer illuminated.
Unplug the pocket scanner and turn off the truck.
