One of my customers’ wives ended up stuck yesterday with their 2001 Buick Century. She had been on the freeway before exiting into the left lane at an intersection stoplight. It would no longer move forward in drive gear. Her husband went to the scene of four wheel tragedy and found the car would move in reverse, first gear, and second gear – but not drive gear or third. He had it towed into my shop where I scanned it for engine and transmission codes after making sure the engine was running well.
It had set a code P1811 which is a transmission code related to the pressure control solenoid. After further research I found out it’s a relatively common code but it means two different courses of action depending on mileage. If the vehicle has over 90,000 miles as this particular Buick, it means major overhaul is the only safe solution. If the code shows up at low mileage the pressure control solenoid can be changed relatively safely. There have been numerous valve body updates so I would recommend major overhaul with all the updates. Many times on the high mileage vehicles the overdrive clutch hub shaft strips.
I’m blogging this today because I’ve run across more than a few of these early 2000’s GM four speed electronic transmission failures in the last year. This customer has had regular transmission filter and oil flush treatments so I don’t believe this failure has to do with maintenance. If it happens to someone coming across this blog you may be able to move the vehicle to the roadside in first or second gear if the vehicle will not move in drive. The P1811 code appeared in each of the past failures so it is one key element. I wish I could have projected some humor in this but it wasn’t possible.