Programming TCM

Hi,

I assume the issue is the terminology. To reprogram a TCM it normally means they need to perform a software update. If this is the case that is not true. A software update does not require any tire size inputs. What was the reason you were having them program it?

However, if they are trying to run a procedure, it may fail due to speed sensors not being close enough.

Did they give you a repair order or something that documents what they did and why they can't do it? If not, ask them for one and I will be able to tell you what the issue is. Then just post a picture of it or scan it and post it to the site. Just block out your address and phone number if it is on there. Thanks

From that description I would ask, what sizes are the front and rear tires? If they are different sizes that could be the issue, it can also be an issue if the tires are very different than stock. Both of these can cause the reported speeds from the wheel speed sensors to be different than stock or worse different from each other. That would create a large problem.

In that case as long as the sizes are the same it shouldn't matter. Where you run into trouble is if you had say a 215 65 17 on one end and a 225 75 17 on the other. Then they turn at different speeds. The tread pattern won't make a difference for that.