Cat Lift Trucks (& Caterpillar) ET4000:
Error Code 40 Every Morning

We have an ET4000 that is several years old but in good mechanical condition. Every morning after we unplug the batteries from the charger (and plug the batteries back into the lift) when attempting to use the lift we get an error code 40 on the LCD. This problem will continue for up to 15 minutes of repeated attempts to start using the lift (i.e. turning the key from the off position to the run position). Eventually the error code will stop showing up and we can use the lift the entire day without any further issue. This includes turning the lift off (key to off position) several times during the day. At the end of each day we disconnect the batteries from the lift and reconnect them to the charger. In the morning the entire processes repeats its self.
  • Posted 31 May 2022 23:48
  • Discussion started by BernieG
  • Wisconsin, United States
Showing items 1 - 3 of 3 results.
Will, the pump and traction contactors are located under the plate behind the seat. The traction contactor would be the same as the line contactor i spoke of.
  • Posted 15 Nov 2024 12:56
  • Reply by swoop223
  • North Carolina, United States
You've been swooped!
swoop223@gmail.com
Can you tell me where on the machine this line contactor is?
  • Posted 14 Nov 2024 13:01
  • Reply by Will_McCrary
  • South Carolina, United States
error code 40 indicates a line contactor OPEN fault during initial self test when powered on.
Possible causes: Line contactor, main wire harness, logic unit, right or left traction inverter.
-First thing i would do is check the inverter UVW cable connections on the inverters for heat related issues or corrosion or looseness. These inverters were notorious for burning out cable terminals at the inverter, in some cases melting the case around the terminal poles.

-Also check the line contactor itself, make sure the tips move freely and are not burned or melted, disconnect the battery and discharge the inverters (use a 150ohm, 25w resistor between the P and N terminals for about 5 secs. Then use a vom and check the voltage between the terminals to insure the voltage has been drained. If there are 2 drive inverters you will have to perform this proceedure on both inverters before doing maintenance on the system.)
Once you have discharged the inverters you can then check the line contactor coil to make sure it is not damaged, the coil should ohm out at about 44 to 65 ohms. the manual specs say [44ohms at -30deg C(-22F) to 65ohms at 80deg C (176F). Anything outside (below or above) of those parameters indicates the coil is faulty and needs replacement.

There are other things to check if none of the above is found to be the cause but we'll tackle that after you do the initial things i mentioned above.
  • Posted 1 Jun 2022 11:03
  • Reply by swoop223
  • North Carolina, United States
You've been swooped!
swoop223@gmail.com

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