JohnShead
Member
My truck intermittently started having erratic speedometer behavior, a flickering check gauges light, no gear selection light, and occasionally no tach. I thought my grounds were going bad again so I cleaned them up and checked voltage drop across them and they were good. After about 10,000 miles of this it started refusing to shift into 3rd giving DTC 81 and sometimes DTC 82. For a while I could clear the codes and it would work fine. It got to the point the code wouldn't stay cleared until the transmission had warmed up by driving for about 20 minutes, then it would work fine until I parked and it cooled down. I rigged up a box with 3 toggle switches to manually operate the shift solenoids to attempt to keep the truck operational a bit longer but it still wouldn't shift into 3rd until the transmission had warmed up after which I get all gears including torque converter lock up. With this device I discovered that when the truck is in a different gear than the ECM is calling for it causes the speedo, tach, gear indicator, gauges light issues mentioned earlier. I checked all of the wires from the ECM to transmission for resistance and they were good. I checked voltage at the transmission connector and there is 12V. The transmission has a good ground. At this point I'm still blaming electrical because of the codes so I replace the shift solenoids. While I was inside the transmission I checked the internal wiring harness and I get 12V at all the connectors when I call for that solenoid with my manual shifter. The new solenoids did not change the behavior so now I think it has to be mechanical. I have the valve body out now and the 1-2 and 2-3 valves are not sticking. Has anyone heard of anything like this or maybe have an idea of how to fix it?
