Hey I recently completed a line boring job on a cat 322 serial number 1ys00304. And as my luck goes now he’s having a issue with the electronic throttle working when it wants to. I would like to help him diagnose this problem because at the moment everyone is telling him that I probably fried something while welding on the end of the stick. As of right now everything seems to work fine except the electronic throttle works when it wants to. When the throttle is not working everything on the monitor seems to be functioning fine, the numbers on the screen follow exactly what position the control knob is in. Machine starts and shuts down like it should whether the throttle is working or not. I need some advice on where we should start looking to fix this problem. Does anyone have a wiring diagram they can send me? Is there a way to pull trouble codes? Thanks
Attached how to access Service Mode and something on Error Codes. I'll send you an electrical schematic. Keep an eye on your messages.
Does it have auxiliary hydraulics with a computer under the engine air filter?
I’m not sure. I know it’s plumbed for a hydraulic coupler. If it does could that be part of the issue?
He doesn’t think so. I’ll have to look at it later
If it has OEM 2way auxiliary hydraulics, there will be a computer with LED screen under the air filter for the engine. Looks like this. And I was mistaken. It's above the engine air filter. When water enters that controller, it does goofy throttle operation, even when not using the auxiliaries.
Thanks for the info. Is there a way to bypass that controller if that is the case?
does it work ok in manual mode if you flick the toggle from the auto manual mode behind the armrest? is the problem intermittent?
He has had some issues in the past with the hydraulic coupler giving him some fits.
Coupler operation is completely independent of all main hydraulics and electronics, save for pilot oil pressure.
We tried that when it first started having issues. While the electronic throttle was not working we could not get it to idle up with the manual control. Maybe we were not going about it correctly. The problem is intermittent with no rhyme or reason as to when it works or doesn’t
Ok. I will have him check to see if his machine has that controller or not.
I would check the following: 1- check if there is an exhaust leakage that usually melts the throttle cable so that the cable gets stuck in some way. could be that its intermittently getting stuck. 2- check the throttle cables (2 of them) are secured to the brackets and the injector pump lever 3-flick to manual mode and check if the throttle is working fine and problem is happening in manual and auto. need some more information on how exactly the throttle is behaving like if its partially moving or not at all when its inop. My guy feeling is the cable that pulls the throttle lever is jammed in the sleeve or sticking giving the intermittent operation. the computer is showing the speeds because it gets the input from engine speed dial, but on the other side the throttle is not pulling the cables. You could just feel if the throttle motor is actually working but observing if that cable Is trying to move or its completely dead.
just saw this, so that would mean its probably a stuck cable, because in manual mode the computer is completely bypassed. and the throttle is going up or down when you flick the manual engine speed toggle next to the mode toggle. you can just change the cables only on these. not too complicated and will cost you about 50 bucks
We will check these things. When the throttle is inop it does absolutely nothing. Does not try to rev up at all. If we were trying the manual mode correctly, when it’s acting up it is inop in both manual and auto but we will try this again.
There is a procedure for changing the cables, but, it requires a homemade controller to set them up. The presence or lack thereof an auxiliary controller is step one in diagnostics, on that series. If present, it intercepts all throttle inputs, even manual override. The failures in that controller by the air filter stumped many a Cat technician back in the day.
you can actually calibrate the throttle motor using the onboard computer. its fairly simple. The hard part is to get the cable into the spindle correctly. but if you measure the original carefully before disassembly, and then install it ok then its fairly easy to get it all calibrated and you don't need a homemade controller etc
Hi lewis, Just make sure you are checking the correct toggle switches, unfortunately my SIS system has tanked so I have no pictures to send you but hopefully you have found the correct switch, its on the right hadn't armrest rear most and theres a couple of toggles, one for changing from auto to manual and the second one that is return to center that you flick up and down to throttle up down.
Yep. We will check this again. We were following the instructions in the operators manual
He is telling me that his machine only has one throttle cable. Are we missing something?
no this is ok. Usually the Perkins engined models had just 1 cable so I would just check thats not sticking. Check it at the injector pump end to make sure that its all attached properly.
Thanks everyone for your responses. Finally made it out to try to do some diagnostics. 2201 is the only active code the machine has. Anyone have any advice what we need to be looking for?
From here... https://www.sinocmpexcavatorparts.com/caterpillar-fault-code/
check the wiring harness from the steppe motor if any of the wires are shorted to ground etc. The motor has a small potentiometer that feeds the computer with the position of the throttle so seems this parts has either become faulty internally or the wirings faulty. You can check the wiring with a multimeter. You can replace the potiometer separately as well but it involves dismantling the stepper motor carefully.