How to Test a Taurus PCMby Cayden Conor
Depending on the year Taurus on which you are working, the powertrain control module (PCM) could be located in one of any number of places. Look in the passenger-side kick panel or under the carpet on the passenger floor. It may also be located under the seat, on the fenderwell or on the firewall. The computer cannot diagnose itself -- you will not be able to use a scanner in the conventional manner to test it. It is up to you to follow "clues" about the computer to determine if it has malfunctioned.
Plug the code scanner into the data link port, which is usually located under the driver's-side dash. If it is not under the dash, check on the driver's side of the engine compartment. The location depends on the year and model Taurus on which you are working.
Turn the key to the "On" position, then press the "Read" button on the scanner. Write down all the codes, then compare them to the code sheet that comes with the scanner. If you have several codes for things you know are working, or it is just not possible that all the components listed by the scanner are bad, the computer is suspect. It is also suspect if the scanner gave you codes that do not exist.
Disconnect the negative battery cable, using the appropriate wrench. Discharge static electricity by grounding yourself -- touch metal. Remove the computer from its bracket, using the appropriate socket. Unbolt the wiring harness connectors, using the appropriate socket. Pull the wiring harness connectors straight off the back of the computer. Take care not to bend the pins.
Remove the cover from the back of the computer. Inspect the circuit boards -- look for burned circuits. Smell the computer. If it smells like dead fish, it is highly suspect. If it has burned circuits -- the circuits will have brown or black marks on the circuit board -- replace the computer.