Transmission issue needs professional assessment

Wheels: Wayne G. writes by email:

“I have a 2000 Mercury Mountaineer SUV that had to be towed to my house because it would not go into reverse when parked in a parking spot at the mall. The transmission has not been shifting right for several months especially going in and out of overdrive. Now I am without a vehicle that I love. Asking around to friends and relatives, I have discovered that many shops do not repair transmissions and instead just replace them at a cost of several thousands of dollars. What do you think I should do to get the vehicle back on the road without paying too much?”

Halderman: You need professional help. By this, I mean that the transmission is electronically controlled and many (about half) of automatic transmission faults are electronic and do not require replacing the transmission. The issue could be a transmission range sensor that “tells” the transmission control module (TCM) what gear is selected, such as forward or reverse. If that sensor failed, this could be the reason for the transmission not going into reverse. A shop that has a factory or factory-level aftermarket scan tool should be used to check for any transmission related diagnostic trouble codes. The shop should also use the scan tool to monitor what gear is being selected by the driver, which could indicate whether or not the transmission range sensor is working. Some basics include:

  • If the vehicle can move forward and rearward, but not shift correctly, the most likely cause is the valve body, sometimes called the brain of the automatic transmission. The valve body assembly has many pressure sensors and solenoids that can often be replaced without removing the transmission from the vehicle, making the cost of the repair less expensive.
  • If the transmission does not move in forward or reverse, then the most likely cause is a fault with the internal parts of the transmission. This is a possibility because the SUV does not move in reverse.

There are several repair options, including:

  • A repair shop that can replace the transmission with a new, used or remanufactured assembly.
  • A transmission specialty shop that could repair the transmission by fixing or replacing the broken or worn parts to restore proper operation.
  • A Ford dealer where the transmission could be repaired by a transmission specialist at the dealership.

In my experience, it is often best to fix what you have instead of replacing it with a used unit that may not be the exact transmission designed for the vehicle. This mismatch can cause computer issues because the new unit may not have the same build code or internal parts as the original.

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