What does P0866 Mean? The Engine Control Module (ECM) monitors the Transmission Control Module (TCM). The ECM sets the OBDII when there is a problem communicating with the TCM. engine code P0866P0866 fixobd P0866dtc P0866obd code P0866obd2 P0866P0866 car codediagnostic code P0866car code P0866check engine code P0866fehlercode P0866P0866 fiatcodigo P0866codigo falla P0866P0866 kody b??dówcodigo de falla P0866 What are the common causes of P0866 ? By far the most common cause of this code is from a defective traction control ON/OFF switch. Liquids spilled into the traction control switch are a very common cause of this type of failure.. Other causes may include open, shorted, corroded, or otherwise damaged wiring and/or electrical connectors. Technicians also report the presence of excessive corrosion in the sensor connector as the cause of this code being stored. How do you troubleshoot P0866 ? If the engine displays a miss and there wasn't a code, determine which cylinder is misfiring. If the exhaust manifold is visible, spay or pour a small amount of water on each cylinder exhaust port. Water will evaporate immediately on good cylinders and slowly on the missing cylinder. If this can't be accomplished pull the plugs and check the condition. Look for missing ground strap or a rusty ground where the fuel tank is grounded to the frame. Check for damage to the wiring harness connector. Check to make sure they are not burnt or corroded. If in doubt, get some Electrical Contact cleaner at any parts store if cleaning of the terminals is needed. Searches related to P0866 Code - TCM Communication Circuit High P0866 P0867
