Cat Lift Trucks (& Caterpillar) EP20KT:
Error Codes 11, 13, 21, 30, 33

Electric forklift EP20KT.
Operator was lifting and the error code 33 came up. He turned it off then on and tried to move but code 13 displayed. Reset again and moved about 10 feet before error codes 11 and 21 displayed. I shut the lift off and turn it back on with no errors indicated, I attempt an action and sometimes it will work momentarily but I soon get the alarms 30 or 33 when using the hydraulics, otherwise I get 13 or 11 and 21 when I attempt to move.
What ever is wrong it will intermittently allow the lift to work, it effects the hydraulic system and the drive system. The battery voltage remains above 36v. The diodes test good, the capacitors test good, the thyristors are not shorted. Any suggestions?
  • Posted 23 Dec 2021 04:34
  • Discussion started by GlenMc
  • Missouri, United States
Showing items 1 - 6 of 6 results.
Final solution, I sent both drive boards to my local forklift repair company who sent them on to Flight Systems Industrial Products for inspection/repair. The repaired drive boards were returned and one was installed to solve the problem.

The Drive board must have simultaneously failed the drive and hydraulic circuits.
The Drive board I purchased from eBay must have had a bad hydraulic circuit and a good drive circuit.
The Drive boards were repaired for $590 and now the forklift works.
Thank you Swoop223 for your help.
  • Posted 16 Feb 2022 00:30
  • Reply by GlenMc
  • Missouri, United States
ok well thats good, the drive board fixed the travel issue, awesome
as for the T1P check? It's fairly easy after you get the buss bars off of it, you don't want to test it while connected.
There are 3 IGBT's, 2 of them (located on outside edge and middle) are the drive ones and the other (located on center most location of the panel rails) is the pump. There are a bank of capacitors on top of those connecting rails also that need to be checked.
i have a couple of pieces of info i can send you on how to check that, email in my sig.
  • Posted 31 Dec 2021 04:59
  • Reply by swoop223
  • North Carolina, United States
You've been swooped!
The drive board came in so I installed it and whallah, the forklift will travel forward and reverse without any problems.
However the moment I attempt to activate the hydraulics the error code 33 appears. The manual suggests checking the T1P but I cannot find a procedure on how to do that. It also suggests the drive board, current sensor, logic card or wiring.
Any suggestions?
  • Posted 31 Dec 2021 04:35
  • Reply by GlenMc
  • Missouri, United States
well you may not be getting a full drop if the system is faulting that quick.
before you order the drive board i would pull out the logic and check the boards underneath. there is a diode board under there that sometimes burns up, the diodes will be obviously burned from the high amp draw from low battery use.
check that before you buy anything.
  • Posted 31 Dec 2021 03:47
  • Reply by swoop223
  • North Carolina, United States
You've been swooped!
Thank you for replying swoop223,
I have tried a couple of times to post a reply and I never see them again. I have checked the battery voltage to be 37.6vDC, but when I attempt to use the hydraulics I immediately get the error code 30. If I attempt to use the drive, I momentarily hear a high pitch sound and then it stops followed by the error codes 11 & 21. The battery voltage never drops below 36.5vDC.
I am going to purchase a drive board and try that.
  • Posted 31 Dec 2021 03:03
  • Reply by GlenMc
  • Missouri, United States
hl GlenMc,
first thing i would do is make sure the battery is in good charge state.
no bad cells etc. cells have the correct level of fluid in them. Once verified then start troubleshooting. A lot of the time when you get a slurry of faults like that a bad battery can cause it or be the cause of a component failure triggering them.

Now as for the codes...
-Fault 33 indicates Field driver fault P - Fault signal from the driver board. This is indicating some fault in the driver board for the pump circuit.
-Fault 13 indicates IGBT driver fault R - Fault signal from the drive board. This is indicating some fault in the drive board for the drive circuit.
-Fault 11 indicates IGBT breaking R - Checks voltage and current of power circuit.
-Fault 21 indicates IGBT breaking L - Checks voltage and current of power circuit.
-Fault 30 indicates Armature fault P - Checks voltage and current of power circuit.
-Fault 33 indicates Field driver fault P - Fault signal from the driver board.

Like i said, check the battery voltage (under load) and see what's going on with the battery.
Other than that you may have some burned diodes on the drive board(s) and possibly some other issues. The only cause i can think of that would cause such issues in both systems is a bad battery.
If you will report back here with your findings on the battery. i know you gave a preliminary on being above 36v but what does it do under load?
total voltage before use after charge, volts per cell before testing. voltage drop during hydraulic motor load. I have a feeling you have a battery issue. It could be a bad drive or H-bridge board but lets start with the battery.
  • Posted 24 Dec 2021 00:28
  • Modified 24 Dec 2021 00:36 by poster
  • Reply by swoop223
  • North Carolina, United States
You've been swooped!

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