Droning gearbox

My 2004 Honda Accord 2.4 Executive auto has developed a droning noise and a slight vibration from the gearbox that starts at around 30mph. The gearshifts are still seamless, and as I have only covered 42,000 miles in 10 years, the engine is still quiet, smooth and feels as powerful as it ever was.

I seem to recall reading that this problem can be caused by a faulty transmission ECU. Would it be viable to source a used ECU from the same model/ year and swap it? If so, can you tell me where the unit is located? Denis Fleming The transmission ECU is responsible for the gearchange and kickdown, which appears to be operating correctly on your vehicle. From the data I have, this unit is incorporated into the main ECU, which should be located below the dashboard, just in front of the driver’s A-pillar.

Even though the overall mileage of your Honda is low, I would consider replacing the gearbox oil and filter, using genuine Honda ATF-Z1 fluid. Check the condition of the old oil to ensure no metallic particles are present. If the removed oil is grey or contains any small particles this may indicate that the gearbox bearings are beginning to wear.

One of the problem areas on the Accord automatic was the torque convertor. When this begins to fail, one of the first signs is burning of the transmission fluid. This can be checked by carrying out the transmission fluid change as described above.