Buick/Olds: 2000 Buick Lesabre Transmission/Service Engine Soon Light, 2000 buick lesabre, buick lesabre

Question
Hello

I have a 2000 Buick Lesabre with 67000 miles.

Recently, I had some hard shifting, so I had the TEC Solenoid replaced.  

After I did this, the car was fine for about 75 miles, and then, the hard shifting reappeared and the Service Engine Soon Light came on.

I took it back to the transmission shop and was told fourth gear was shot and I needed a new transmission.

I put a new transmission in the car, per the recommendation of the shop.

The second time I drove the car with the new transmission installed, the Service Engine Soon light came on when I drove up a hill.

Also, The car seems to be chugging a bit.

The good news is I have not felt a hard shift, yet, but why would the Service Engine Soon light appear?

Is this related to the transmission?  Or something else?  And if it is something else, why would I have needed a new transmission?

Answer
Tom, I believe you have been had.

The story seems to tell me that you may have needed a new torque converter or converter sensor, but not a new transmission, I mean on a 2000?...not to mention that 67000 isn't as much as you think. The service engine soon light would likely have come on due to the torque converter sensory relay, located as a black box with "relay" on a sticker on the side of the black box. This is what tells your transmission to shift when speeding up or slowing to a stop.

Since you noticed the light coming on when going uphill, it's likely that the sensor relay didn't upshift at the correct time and the car didn't go into 3rd gear like it should have. this will cause the motor to push hard on 4th gear and possibly damage it. (That's probably why the garage told you that you needed a new transmission because of the 4th gear), but that can be repaired. Anyway, since you have a new transmission now, you might as well take care of the problem now by getting a dealer or reputable garage to check the torque converter and it's relay.

You'll be able to tell if it's a problem other than the transmission itself by doing this:

1. Get the vehicle up to operating temperature
2. Accellerate up to 50 mph (around there anyway) and then press down on the gas a bit. See where the pedal is before it kicks down into 3rd gear, if you notace ANY shuddering, shaking ar hessitation before it shifts...OR...if you need to put it pretty much to the floor before it shifts, then it is not the transmission, it's a relay or a torque converter.

3. If you notice it shifts but slips right back to 4th...OR...if it shifts and does not pick up speed or has to shift a few times to pick up speed, then it is the transmission and you'll need to get it to a dealer to get it fixed right before puting in yet another transmission.