Komatsu Main Controller

I have a Komatsu PC 220 LC6 & paid the dealer to tell us our the part # R7834-21-7002 Controller needs replaced (wow that hurt). All functions work except the swing. We have the controller by-passed with the by-pass topple switch. The controller is $ 2500.00 +, can or does anyone repair these controllers ?

Thanks

Try Great Lakes Eq Company Phone: (815)220-7750 sometimes they have surplus. Looks like it updates to a 7834-21-7003 also, with or without the R for reman.

If you're a gambling man there are some available on Ebay:
http://www.ebay.com/itm/Komatsu-exc...oller-7834-21-7002-7834-21-7003-/261888218263

does the auto idle function work when u try to swing left or right?

It occurs to me that somebody does repair these, as that's a reman part number and the core charge is near a grand. So they're repairable, but it seems at this point only the factory does the repairs?

The Auto Idle does work in all functions, as long as the toggle by-pass is in the up position.

When it's in the normal position it doesn't work? Almost sounds like a pressure switch issue.. Which switch is flipped emergency pump drive or swing switch?

Something really sounds wrong about this. The auto idle is not supposed to work in the bypass position because the computer is "bypassed".

There is a swing brake bypass which should be next to what is called a Prolux switch which bypasses the computer. Do you know where the swing brake bypass switch is located? Do you have any fault codes on the monitor panel? Have you checked the swing brake solenoid coil for resistance or being shorted. Have you checked the wiring to the swing brake solenoid for voltage to start with? Have you checked the oil in the swing machinery box? Maybe you have broken gears. There are a lot of things to check before throwing a ton of money at something without proving it needs to be replaced.

I think you are getting some bum information from a "dealer" that probably doesn't know what they are doing.

Yes it's the Swing Brake switch, we have it bypassed & back working. Then Kom mechanic put one he had in truck & everything worked & there was no faults.
He proved the controller needs replaced.
Thanks

Do me a favour. Put all switch back to normal.
Rev engine all the way up with the auto idle on.
Then wait for the engine to rev down. Touch each function and wait for rpmto drop before touching the next.

When you try to swing what happens? Sound change? Engine bogs down? Try's to swing but chatters?

If you are satisfied you need a controller then you will likely only find one that works from the Komatsu dealer. I've never heard of anyone who could fix the things and guarantee they would work.

Good Luck!

We put all switches to normal, The engine won't rev up & the swing is locked. If trying to move machine w/o switch flipped it will kill the engine. Flip the bypass switch & all functions work.