CAT239D Limp Mode yellow Explanation Point Flashing

Hello guys and gals. first time poster hoping one of you can lead me down the wright path. I have a CAT239D SN# BL903441 And 2141.3Hrs Original OEM harness's It goes into limp mode with on load full power. I have 5Volts on both yellow wires #834 on both #1 sensor plugs 5 volts on the red wire #L730. I Know that I need 8Volts on the sensor wire #834 I have 8Volts on the yellow wire #P769 but it dead ends at the sensor wiring harness EXT Plug At the big Deutsch plug on the back the yellow wire#834 has 5volt on both sides any help Thanks

if its not broken fix it said: It goes into limp mode with on load full power. Click to expand... This happens while the machine is moving or when you use the hydraulics, or both.? Are there any Active Diagnostic Codes present.?

Thanks for getting back to me. This happens when the machine is moving. at WOT after driving it for a few minutes. as for using the hydro's I don't know I can lower the cab and try. and for the codes I do not know. I do not have a scanner and this loader doesn't display codes It just has the 15 symbols that light up.

Nige I can't pull it out of the shop without it going into limp mod. to try and rase and lower the arms. it does go into limp when I turn right and left forward and backwards.

if its not broken fix it said: Nige I can't pull it out of the shop without it going into limp mod. to try and rase and lower the arms. it does go into limp when I turn right and left forward and backwards. Click to expand... It sounds as though there is one or more Active Codes for track motor speed sensors - of which htere are four altogether. The best way to determine which one would be to hook ET up to it. In the absence of that the only method may have to be test the performance of all four sensors. Long-winded but it will get you there in the end. Do you have an electrical schematic.? Because you're going to need one.

Nige I do not have a Ele schematic. Looks like I am heading to the Cat dealer to pick one up. I thank you for your help.

if its not broken fix it said: I have 5Volts on both yellow wires #834 on both #1 sensor plugs Click to expand... There is a signal on that wire when the machine is moving, but you cannot measure it by voltage. It requires a multimeter capable of measuring duty cycle. The voltage you see is what's known as pull-up voltage and is used for measuring the integrity of the signal wire. if its not broken fix it said: Nige I do not have a Ele schematic. Looks like I am heading to the Cat dealer to pick one up. I thank you for your help. Click to expand... Check your message inbox for a schematic.

Awesome thank you for that info Nige.

Simply explained there are two speed sensors in a common body on each side of the machine, call them #1 and #2. The Machine ECM determines direction of travel by which sensor signal is lagging or leading. Illustration of the LH sensor below.

Here are the troubleshooting procedures for all four speed sensors.

Thank you for all your help and info Nige I appreciate it.

First thing I would suggest is to remove each sensor and make sure the nose end of it, which is the part that detects the tone ring in the drive motor, is clean. They tend to attract metal filings.

That was the first thing that I did was to check the sensors on each drive. and I checked each harness going to each sensor. When I get this fixed I will post an update to what I found and the fix. Thanks for all your help.