Just picked up a 2008 CAT 246C with codes 2687-8 and 2688-8 for the right drive motor sensor. I’m following the troubleshoot process in the manual which states to test the harness side ground and power for the sensor (should be 8v) but I can’t seem to get any solid reading with my multimeter? I tried the left drive motor harness to see if I could get solid numbers on the side that works and same sporadic readings. I tried a couple different multimeters with similar results. Am I missing something? The machine also seems to have slow boom going down. Booming up is fast and normal, but going down takes about twice as long. Could there be a check valve or something to look at? Thanks, Mitch CAT0246CV JAY01322
Check your message inbox. An electrical schematic is on the way. The fact that you have both RH motor speed sensors failing the same way is an indication of a problem with either the 8v supply from the ECM or the ground back to the ECM (note it's not frame ground). TBH the best thing you can do is start at the ECM and measure the supply voltage to the speed sensors at that point. If you don't have 8v at that point then some head scratching is going to take place.