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590 sl 2 park brake kills trans controller

alan walker

Member
Joined
Nov 14, 2019
Messages
9
Location
southeastern IL
Good evening, this forum has been very helpful to me over the years, but now I need help.
I have a case 590 super l series 2 powershift, When I engage the parking brake, I lose power to the trans controller.

The park brake switches are working, the seat lock switch is disabled, but it works as it should when it is hooked up.
The other suspicious thing or two, is that there is a wire hanging down that looks like it needs a diode, but its empty, and it makes no difference when I swap in a different diode.

The diff lock solenoid clicks even with the relay removed, but that doesnt change the problem either.

When I engage the parking brake power is lost from the clutch relay , and that seems to kill power to the trans controller.

I assume there is a bad wire somewhere but we've been over it twice with a fine tooth comb already.
 

alan walker

Member
Joined
Nov 14, 2019
Messages
9
Location
southeastern IL
Did you try to see if unplugging the diff lock solenoid changes anything?
I did try disconnecting that solenoid with no change but thanks for the suggestion.

In more testing I blew the number 1 fuse that powers the trans controller. with that fuse blown, the clutch relay buzzes, it is getting power back feed from fuse 2. That should help me find the problem, but its not quite clear yet...
 

alan walker

Member
Joined
Nov 14, 2019
Messages
9
Location
southeastern IL
Why do you want the TCU to work with the parking break on?
Well, the way it is designed to work, is for the alarm to sound if the trans goes into gear with the park brake on, so there is a wiring issue, I would like to fix before it stops me dead. The TCU completely reboots and goes through its cycle when this happens.

The owners manual calls out setting parking brake tension to hold the machine up to 1500rpm in gear, so I know it is not supposed to kill the power to the tcu.
 

alrman

Senior Member
Joined
Jun 20, 2009
Messages
3,303
Location
QLD Australia
Occupation
Diesel Fitter;Small Business Owner;Cleaner
Just curious, are you saying the lights go completely out on the TCU display when you apply the park brake?
 

alan walker

Member
Joined
Nov 14, 2019
Messages
9
Location
southeastern IL
Just curious, are you saying the lights go completely out on the TCU display when you apply the park brake?
Yes, the lights go completely out, and when you release the brake it goes through it's startup sequence, the test and fault lights flash and it shows the mode, then goes to N2 or whatever gear your in. if you are in F or R on the shuttle handle, you have to go back to N and then select a direction again.
 

highwayghost

Senior Member
Joined
Nov 1, 2019
Messages
315
Location
Pittsburgh, PA
Occupation
Emissions Analyst
With all those different things that don't seem connected I would be looking at the ground wires and connections. Put on some temporary ones to the things that are giving trouble and see if that helps.
 

alan walker

Member
Joined
Nov 14, 2019
Messages
9
Location
southeastern IL
I agree on the ground's being a possible cause, and I don't think I've found them alll yet, but the battery, frame, and cab main grounds have been cleaned and tightened.
 

Billrog

Senior Member
Joined
Mar 26, 2016
Messages
722
Location
Armstrong, British Columbia
Occupation
band mill , backhoe and dump truck
When multiple things get activated I found it's generally a fault in a corroded plug effecting the circuits threw the ground.
 

alan walker

Member
Joined
Nov 14, 2019
Messages
9
Location
southeastern IL
Well, after a full day of troubleshooting in circles yesterday, we finally made some progress. It seems like when I had a shop replace the speed sensor in my transmission a year or so ago, they just randomly plugged in things where they would fit.

The left hand parking brake switch was plugged into the harness for another declutch switch, instead of the brake switch. I assume a standard trans has a declutch switch on the end of the FNR lever, mine is a kickdown switch.

Anyway my TCU now works normally. no more back feeding on relays. The diff lock solenoid still works without the relay, but I see the standard trans has a separate diff lock connector from the power shift trans, so I assume it is hooked up to the wrong connector somewhere under there too, but I havent found that error yet.

I'd like to thank everyone for there help.

I also can't blame everything on the shop, because I got to aggresive with some brush clearing a while back and messed up the wiring harness to my bucket quick coupler, so I may have "fixed" that brake switch harness when I was under there myself.
 

alrman

Senior Member
Joined
Jun 20, 2009
Messages
3,303
Location
QLD Australia
Occupation
Diesel Fitter;Small Business Owner;Cleaner
Yes, thanks for letting us all know what you found.
I guess the real question is - why wasn't this issue dealt with 12 months ago when the machine came back from the "shop" :rolleyes:
 

alan walker

Member
Joined
Nov 14, 2019
Messages
9
Location
southeastern IL
well, its a long story that starts with the seat swivel switch going bad, so my son pulled the alarm relay. I don't use the park brake much, and we were doing a pretty thoruogh service on it this winter. trying to fix everything possible.
 
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