Ok this machine has me stumped, I got called out to look at it because the operator said that it was losing travel speed the farther he tracked with it but if he went back to park and then pulled the lever back into go it would go back to normal for a distance and speed would start decreasing again. He is correct it is doing exactly that in forward and reverse. I plugged in ET and noticed that the right track speed sensor was not working, so I replaced that and have a spot on speed reading from right track to left track. Re calibrated all peddles and travel lever and the issue is still present. Every input to the computer is correct and steady. All pilot and track pressures are spot on where they need to be. The reason that the machine is decreasing in speed is because the computer is decreasing current to the travel solenoids as you travel again in forward and reverse identically. What I can't figure out is why the computer is doing this?!? Hopefully someone here can help me with this problem! Thanks Tommy!
Check the engine RPM input to the ECM. If you know the ECM is slowing the travel down it must think the engine is losing RPM. Later Bob.
Hey Bob that makes sense and I will investigate that thought further when I get back to the machine. But i know the trans ecm does not show engine rpm it only shows "high idle" or "not high idle" signaled from the limit switch in the console when the throttle lever is pulled all the way back. I will have to check the schematic and see if there is a speed sensor input and go from there!
Speed sensor for trans ECM is in the flywheel housing and counts the ring gear teeth. A damaged tooth or bunch of teeth can send a glitch and mess things up. A break out harness(homemade) and a scope meter will help, if you don't get a clean frequency check ring gear teeth. Later Bob
ok so i got back to the machine today went in and visually checked the engine speed sensor and it all looked good checked the connectors and they were also good. Got the computer on it and verifed engine speed with ET rpm signal is good and coming in steady no odd fluctuation. The problem still remains. No active or stored codes in the ECM. high idle limit switch is working all peddle and travel lever readings are constant without fluctuation when traveling.
You should check the signal coming out of the sensor on the flywheel with a scope meter. If the engine has electronic fuel control ET will get it's RPM signal from a different sensor. What happens when you lock the brakes and stall the drive? Does the RPM hold flat under load or whip up and down? Later Bob