* Transmission Fluid Level and Condition: This is the first thing to check. Low, dirty, or burnt transmission fluid is a very common cause of transmission problems. Check the fluid level with the engine running and warmed up. If it's low, add the correct type of ATF (Automatic Transmission Fluid) specified in your owner's manual. If the fluid is dark, burnt smelling, or contains debris, a complete fluid and filter change is necessary.
* Transmission Temperature Sensor: This sensor monitors the transmission's temperature. A faulty sensor can provide incorrect readings to the PCM (Powertrain Control Module), leading to erratic shifting and the OD light flashing as a protective measure.
* Overdrive Solenoid: The overdrive solenoid is responsible for engaging and disengaging overdrive. A malfunctioning solenoid can prevent overdrive from engaging properly, causing the light to flash.
* Speed Sensor (Vehicle Speed Sensor - VSS): A faulty VSS provides incorrect speed information to the PCM. This can cause the transmission to shift improperly and trigger the OD light. The PCM relies on the VSS to determine when to engage overdrive and to properly manage shifting in the lower gears.
* PCM (Powertrain Control Module): In rare cases, a problem with the PCM itself could be the root cause. This is less likely than the other issues but should be considered if other components are ruled out.
* Wiring Harness: Damaged or corroded wiring in the transmission harness can interrupt the signals between the sensors, solenoids, and the PCM. Check for any obvious damage or corrosion around the transmission and connectors.
Troubleshooting Steps:
1. Check and change the transmission fluid and filter: This is the easiest and cheapest step, and it often resolves the problem.
2. Have the codes read: Use an OBD-II scanner to read the trouble codes stored in the PCM. These codes will pinpoint the specific problem area. A flashing OD light is often accompanied by diagnostic trouble codes (DTCs).
3. Inspect the wiring harness: Look for any signs of damage, corrosion, or loose connections.
4. Professional Diagnosis: If you can't identify the problem with the above steps, take your Contour to a qualified mechanic specializing in automatic transmissions. They have the tools and expertise to diagnose the issue accurately and perform the necessary repairs.
Important Note: Continuing to drive the car with a flashing OD light could cause further damage to the transmission. It's best to limit driving to short distances and seek professional help as soon as possible.
