95 Chevy Suburban stuck in 3rd gear

1995 Chevy Suburban, currently at 150,000 miles, Prior owner had transmission rebuilt prior to 100,000 miles. While towing my 18ft camper trailer on a recent trip every time I started off from a stop I had to really push on the gas to get going. At first I though the emergency brake was on, or I had a flat tire. I then noticed the automatic transmission was not shifting when I had it in D. Checked the transmission fluid and it was full. The transmission seems to be stuck in 3rd gear. When I move the shifter to 2 it will shift down. Reverse is also still working. Am I in for a costly repair?

Yes.

I seem to recall a similar era S-10 with the same problem coming in to our shop. I think it boiled down to being a bad ignition switch. My co-worker worked on it, so I’ll probe his memory banks on Monday, & relate what he says.

First of all, you need to get a scanner on it. There will be a 2 digit trouble code which will give us an idea of what might be going on. One thing you can do until you are able to find someone with a scanner is check for power at the plug on the side of the transmission. Unplug the large plug on the passenger side of the trans, and with the ignition in the “ON” position check for 12vdc on the PINK wire. If you have 12vdc here then the scanner is needed to read the codes. If you do not have 12vdc then this is why you are stuck in 3rd gear limp mode. Dont automatically condemn it, this could be something very simple.

transman