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Volvo L20F single lever controls, 3rd function in-op

Bullitt

Active Member
Joined
Oct 30, 2022
Messages
37
Location
Central PA
Occupation
Manitou / Gehl & Yanmar Tech, Rental Monkey
I got a real head scratcher.
Volvo L20F-P VCE0L20FL01705343
Rocker switch for forward reverse travel selection went bad
Replaced joystick with P#: VOE15211721
Travel selection returned however 3rd function became in-op
Tested for voltage @ RF01and had battery voltage, ground at 3101 which had .2ohm to negative battery terminal
Load tested power and ground circuit at joystick connector and only dropped .2v with load test pro
removed connectors from PWM9150 and PWM9106 and tested for power and ground when using the 3rd function roller switch SE9147
both terminals of the connector stayed battery voltage positive

took joystick apart and found that battery voltage and ground coming into CU9141
All other circuits from CU9141 where also battery voltage
there is 3 wires that go out to the roller switch for 3rd function, all 3 wires were 12v
3 wires that go out to a potentiometer to adjust 3rd function range, all 3 12v
2 wires that go out to a micro switch to 'lock' 3rd function, both wires 12v
3 wires that go out to solenoids to control pilot pressure on the 3rd function spool, all 3 12v
All of this remains constant with actuation of the roller switch

Checked the harness for shorts and opens, no terminal has any continuity to another with the joystick unplugged
All of the other microswitches function fine as they are on another plug and are separate entirely from the 3rd function circuits
I gave the solenoids for the 3rd function pilot solenoids 12v/5a and confirmed that they do work and hydraulic function is present at the hose couplers
Contact Volvo dealer and talk on the phone with lead tech for 2 hours running through checks again over phone
He suggested replacing the joystick with another unit, they double check part numbers, VOE15211721 is right, so they give me a warranty exchange
Replace joystick again, issue remains the same

I'm attaching a diagram that I colored on,
RF01 is voltage supply
R9141 is a external potentiometer RF06-08
3101 is a ground
CU9141 is what they are using for modulation of the solenoids based on inputs, the 'central unit' if you will
SE9147 is the roller switch for activation, it has 3 wires too it, in the diagram they are kind of showing it as a wire on both sides but it isn't
SW9147 is the detent lock for locking the 3rd function
PWM9105 and PWM9106 are the solenoids that control pilot pressure to the 3rd function spool, RF03-05

As far as the parts guy can tell they never changed the part number of the joystick, the harness, or the solenoids
In my head there is something wrong with this joystick... either bad manufacturing, or a wrong part
I'm basically at a stand still with the machine now, you can't work the 3rd function for the sweeper or change the attachment because the attachment release needs 3rd function hydraulics to operate. Volvo wants me to bring the machine to them, but it would probably be more economical to scrap it..
Anyone that might have some insight please help me out!
 

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Pickawinna

Member
Joined
Aug 30, 2023
Messages
13
Location
Australia
Bit too much for me to wrap my head around at the moment. But, am I right in thinking that all the solenoids are being powered all the time? Therefore the 3rd function is trying to do everything which in fact means it is doing nothing?
Tried disconnecting back to a single solenoid and seeing if it functions when controls are operated?
 

NC Fabricator25

New Member
Joined
Apr 15, 2024
Messages
1
Location
Charlotte NC
I see this is an older post, but curious if you got it sorted out? I'm in the beginning stages of working on a new-to-me L20F and trying to read up where I can.

Thanks
 

Bullitt

Active Member
Joined
Oct 30, 2022
Messages
37
Location
Central PA
Occupation
Manitou / Gehl & Yanmar Tech, Rental Monkey
I see this is an older post, but curious if you got it sorted out? I'm in the beginning stages of working on a new-to-me L20F and trying to read up where I can.

Thanks
Volvo dealer sorted it. They said there was a wire wrong, but I call major BS. Anyways I hope I never have to see that machine again! The company that operated it did NOT take care of it and had so many issues.
 
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