Resetting Automatic Transmission Control Module

Did you read my last post about automatic transmission maintenance you can try?

Maintenance of automatic transmissions can be fiddly and is usually ignored based on the experience I have seen in a lot of used cars.

It gets forgotten about until something goes wrong.

And the fixes can usually be quite expensive – especially if you need to get it serviced or rebuilt at as transmission specialist.

But after you have done the preventative maintenance like flushing the fluid and changing the filter, sometimes it is true to the gear change timing can get jerky, or out of sync.

This sometimes happens when the car has been driven unusually for a period of time (hard or soft) or when the battery has been changed and/or flat.

There is a process you should try which is known as resetting the part of the car’s computer which governs the running of the gears.

Check your car’s service book and/or instruction manual. The process may be detailed in there.

Probably not though, so check online forums.

Some cars, like Mercedes Benz have a much more cryptic process than the more generic one detailed below.

They require various procedures be done before and after to determine the steps of the process including depressing of brake pedal 3 times and other weird stuff.

A GENERIC Reset Process To Follow

It will work for many automatic transmissions, but certainly not all of them, so please do your research.

So, to give your car the best chance of smoother gear changes, do this process exactly:

• Take battery terminals off and leave off for at least a few hours to completely drain charge from any capacitors.
• Cold start engine. With foot on the brake, move the transmission between park and lowest gear slowly – 3 times.
• Take car on a 5 minute, very slow drive on quiet streets (maybe with hazard lights on in case of traffic) not exceeding 25km/h and very light acceleration.
• Decelerate without braking, to a full stop. Let idle for a minute or so.
• Stop vehicle and let sit for a minute or so.
• Again with foot on brake, move the transmission between park and lowest gear slowly – 3 times.
• Take the car on another 5 minute drive, this time not exceeding 80km/h and using light and even acceleration/deceleration.
• Decelerate without braking, to a full stop. Let idle for a minute or so.
• Stop vehicle and let sit for another minute or so.
• When driving normally for next 10-20 kms, avoid hard acceleration and braking.

Then drive the car easily and carefully without hard acceleration for the next 80 kms or so to “retrain” the module.

This has worked and ironed out jerky gear changes in auto transmissions for me before on many occasions.

I hope it works for you too.

Call me on 0411 362 229 so I can make you an offer on any car you have to sell today in Brisbane or surrounds.