Working on a 950f loader that has me stumped. Occasionally when shifting into 2nd, the loader doesnt seem to engage the gear. i can flip the neutralizer switch up and back and then she goes. happens in reverse as well. trans pump shows plenty of pressure, stall test looked good as well. Installed a new number 5 solenoid last week and shifting seemed improved. codes: 621f02 downshift signal not correct. 635f06: Speed 2 short to ground 668f02: shift handle signal not correct. not sure if the codes are active but i can get them to cycle via the dash switch. In manual, all the gears work but 2nd f or r. seems to happen when warm only. considering a new column shifter and maybe another solenoid? thoughts? Thanks in advance.
Oh, i tested the voltage to the shifter and it matched battery voltage.
Most likely not the transmission ECM. Probably a leaking sealing ring on the second speed clutch pack. Do a pressure test when the problem is there and surely you will find the second speed pack not making the pressure It could also come from control valves
Thanks, awaiting pressure testing equipment to arrive and will do the tests as per the manual. just went through the dash and replaced a bunch of bulbs, now noticing machine will not even go into any gear unless the neutralizer switch is active on the dash. Is this normal or am i misunderstanding this?
I am not sure but if neutralizer is enabled then the machine will not move, its like disengaging the transmission. I came across this problem a few years ago so I will need to do some refreshing
If i read it correctly, with the switch active on the dash, the brake pedal neutralizer will engage when brakes are used. With it off, the brakes will only apply brakes and not neutralize the transmission. I could be reading it wrong.
Your are right, sometimes the switch is only on one paddle . You might make sure there is not dirt under the paddles making the brakes drag.
Reading over it again this morning, I believe to understand that the machine should dirve when the dsh neutraler switch is off. The machine certainly does not, so now im even more baffled.
Gear indicator shows selected speed & N, wether in F or R with neutralizer in off position. *baffled*
You have an electrical problem sending a bad signal to the ECM and tricking it into neutralizing the trans. From what you say cycling the switch seems to reset things. This signal is likely one of the codes. Almost need ET to check things out unless you have wiring schematic. Later Bob
Oh man. I do have the factory schematics but awaiting my multimeter. I was going to go ahead and get a new brake mounted switch on the way. My pressure testing gauges should be here soon as well, incase im having electrical and mechanical failures.
Those ECM's are constantly monitering the wires and components for shorts and opens then set a code. They will catch intermittant (worst) problems too. Very few circuits controled by the ECM have a fuse, they see a problem, set a code and shut down the circuit untill problem is fixed. (load is correct) Always have a spare good solinoid to plug in to the circuit when checking voltage or the ECM can send you down the wrong road. For this reason you should have at least one set of spoons to "BACK PROBE" the circuits while they are complete(connected) while working that far out. Later Bob
Thank you for the information, I'm a bit green to all this and have much to learn. This wasn't the job i was called out here for so i am very I'm going to pull the seat and uncover the solenoids so i can see if it is being energized when in 2f but not moving. Needing to brainstorm the neutralizer switch some more. No cat et port and no digital display on the trans control box behind the seat either.
I have removed the seat and pulled the cover to acess the solenoids in preperation for pressure testing. Decided to turn the machine on and flip through some gears, stopped before i could test the energized coils as hydraulic fluid was gushing in between shifts from a hole between number 1 and number 5 solenoids. i see the hole pictured on the diagrams but no definition. nor a mention on how to prevent a mess while testing test
I get the feeling this trans has solinoids under a cover, basically the old cable shift trans with solinoids to move the spools. This may not be your problem but I had a 980 going out of gear intermittently and needing to be shifted out and back into gear to keep moving. It happened at higher RPM and occurred at lower speeds the longer it worked. The alt was overcharging and causing computer problems. Check alt voltage when you get your meter. Later Bob
Thanks Bob, I will check that tomorrow. Got my meter and began trsting somethings. Found the downshift switch to be malfunctioning, and a broken spring hanging up the brake pedal mounted neutralizer switch. Fixed it short term. Installed new solenoids on speed 1 and 2, and also installed a new column shifter. Took the machine on a test drive and amidst my joyful cruise in 4th gear, the machine put itself into neutral. Gear selector wasnt registering so i had to shut the machine down and restart to move it. That is a new problem! And to top it off upon returning to the shop, she downshifted into 2nd as i skowed down and then would not move at all. Popped the neutralizer lock out and she went back into gear and i called it a night. Man am i discouraged, Thank you for the continued help.
As you are running, do you notice the alt charge light flickering at high revs? Your problem is very similar to the 980 we had. Early morning start and it would run better, hold in gear to full revs. As machine was tested longer and batteries charged up trans would drop out at 1300 then 1000 RPM. To get it driving again required shifting to neutral and back into gear. We disconnected the alt out put wire and it held in gear at full speed. Hooked up wire to check alt and it had blown from high voltage. Exc alt fixed that. Our trans shop had a similar problem, rebuilt and tested a trans twice that had been rebuilt by someone else. Worked perfect on bench but not in machine. At the time I had no ideas but it came back to mind when we worked on this one. Later Bob
Have not noticed anything to that tune but today i will unhook the alternator and see if that effects it at all. thank you for the suggestion.
Alright, took some more test runs with the alternator disconnected and found continued problems. voltage at alternator was 29 idle and 28 high idle. i opted to hook up a pressure testing gauge to the pump pressure outlet and drive. When she gets warmed up it seems gears one and two stop working at all. pump pressure reads 360 and when shifted, drops to 120 and bounces back to 360. Sometimes when shifted into 2nd or 1st, the pressure will drop to 110 and just begin bleeding off. Other times the pressure drops to 120 but only for a split second of the normal 1 to 2 seconds it normally takes and returns to 360 psi. Upon giving it throttle the wheels barely move as if it wants to go but nothing happens. Rarely does reving the motor up do anything to put it into gear. Beyond that while driving in 4f at 20mph, it went into neutral and back into gear sevetal times before staying in 4f as i let off the throttle. All of this with the all disconnected. Am i facing electrical and mechanical failures?
Well you ruled out the alt. Now there is a modulation or solenoid shifting problem. The pressure drop and return (modulation) sounds good sometimes but the fast modulation makes me think you might only be getting one clutch not two. The neutralizer drops out the direction clutch. Check wire from pedal switch to control lever. Later Bob
The gush of oil durring a shift is normal as long as it stops after the shift is complete. Have you checked the suction screen for debris/metal? Troubleshooting may be a waste of time. I agree that you need to test pump/P1 pressure while the problem is active! Also the neutralizer circuit would effect all speeds not just second.
Thank you for the continued replies guys, I appreciate the continued help. I was working on another machine today as the loader was in use. Good to know the gushing is normal, i need to rig up a way of running the machine and not making a huge mess out in the field at the same time. Next time i get my hands on the machine, i will do a simultaneous pump/p1 test and let you know what i find. Can i remove the metal suction screen without draining the trans? I did pull the trans filter but have not cut it open yet. Im suspecting a mechanical failure causing the 1 and 2 speed issues when hot and maybe a intermittent short causing the trans to occasionally go into (selected speed) N. Thank you again for your help, I really appreciate the help. I hate being new to these things.
You will lose some oil but not a lot.
When pulling the metal suction screen?
Yes
Went ahead and drained the metal suction filter. No metal chunks found in magnet. Couple of little pebels in the screen but no mechanical parts. Strangely, I found two small pieces of screen but not of the metal filter itself. Guessing a screen on the trans fill tube? Currently rigging up a second line so i can do the pump/p1 test.
[/I]are you saying there was no screen?
The suction screen is behind a 4 bolt cover on the engine side of the drop box on the right just above the drive shaft.
No, i meant that in the screened portion of the filter, i found two pieces of the same screen like material but they werent to the suction filter itself. Maybe off of a solenoid or guessing maybe a screen in the trans fill tube?
Alright managed to do some pressure testing on P1 and Pump at the same time. I ran into town so I could type this up from a computer instead of the cell phone I have been using for all previous information. First off the discrepancies: P1 initial pressure is supposed to be 80 psi at idle, 1F, neutral, I get 300 right off the bat. Speed clutch minimum pressure is supposed to be 320 psi in any gear, I have 280-295 across the board all gears. Direction clutch is supposed to be 55 psi lower than P1, and at idle I get 330 psi, which is above my P1 pressures. From idle to high idle, my psi on P1 only goes up about 10 to 20 psi, in all gears. On this test drive 2F/2R worked fine but 1F/1R stopped engaging at all. I did notice however that 2F and 2R are slight lower on the P1 psi ranged than other gears. 2F: 280 psi, 2R 285 psi, all other gears 295psi. When shifting into 1F or 1R, the pressures on both pump and P1 dropped to normal psi as other shifts, but instead of the 1 second to shift, it happened in a millisecond and then the vehicle did not move with the exception of slight power going to the wheels but only moving them a couple of inches in the selected direction. Another consistent issue I noticed was the difference between downshifts from 4F to 3F versus 3F to 2F. Shifting from 4F to 3F, the pressures drop to normal shifting psi and after a second go back to pump 360, P1 295psi. Shifting from 3F to 2F, the pressures will drop for a slight moment, bounce back up to pump 360psi, P1 280 PSI, THEN drop again, and after the normal pause, go back to running pressures and 2F actually engages. For some reason the shifting always takes that extra couple of moments for the random pressure fluctuation before the actual shift occurs. I also experienced a random switch from 4F to 4N while driving down the road at 18mph, it did it several times very quickly but too fast for pressures to drop. After letting off the throttle it stayed in 4F and didn't give me any troubles. Thoughts?
Oh and in one instance, shifting from 1F (non working at the time) to 2F, the pressures dropped to shifting pressures. Pump 50 psi?, P1 30 psi? and then stayed there. In the 20 seconds it took me to jot the notes down, pressures popped back up and machine went into gear. Thanks in advance for everyone's continued help!
Got me confused here too Mugly, check out the shift choices you have. Sounds like they might be causing some of this. Later Bob
The baffled feelings continue. Disconnected the dwnshift switch which was on the fritz and after a test drive found no change in the issue. Defintely only happens when heated up. I tested for continuity between wires from the harness at the trans ecm. Interesting thing i found was that Sol 5, Speed 2 has continuity to Sol 1: Rev, Sol 2: Fwd, Sol 3: Speed 4, Sol 4:Speed 3 but NOT to Sol 6: Speed 1. Thoughts on how to proceed???
That continuity is likely common ground. Might want to unplug the solinoids and check for shorts across wires. Then check each solinoid for resistance, cold and when trans is warm. Heat might be shorting a winding. Later Bob
To make sure I understand correctly. Unhook the harness going to trans and do a continuity check for possible shorts? Then, unplug the solenoids and do a continuity check on each individual solenoid both cild and warm to see if resistance builds significantly with heat? With the new solenoids in Speed 1 and 2 it almost makes me suspect the harness. Man this is frustrating. Thank you for the ideas.
Unplug the harness from the control and the solinoids then check for shorted wires in the harness alone. Look for DROP in resistance when warm. That would indicate a breaking down of the coils insulation and the voltage shorting from winding to winding not going all the way around. Less effective wire length and less resistance. Later Bob
Excellent, I'll try this when possible to have the loader for a day again.
Just wanted to update everyone on this. We ended up throwing an ECM in the machine based on the wide range of non consistant variables on both the trans pressure side and the electronically shifted side. The ECM fixed the issue and the machine has worked without issue since.
It's a hard pill to swallow, throwing expensive parts at it but it worked? A bad ECM is hard to diagnose, it's what's feeding you your trouble shooting info. Later Bob
I'm glad we started on that end instead of the wiring harness along the way to the ECM. An interesting lesson for sure.
A bit late I know, but did you try re-flashing the ECM before you declared it "officially dead"..? Reason I ask is that I've seen a number of cases where the ECM "loses" a bit of the programming data and goes on the fritz. Sometimes we even had to use a special file to "blank" the ECM first, then flash the software back into it. Often this solution worked and was much cheaper than a new ECM. Think of it like this. The ECM is a computer and as such needs an operating system (flash software file) in just the same way as your home PC uses Windoze. The difference is that your PC has a self-diagnostic and (limited) self-repair facility, an ECM does not. That's why often the cure for an ECM that's not behaving correctly is a re-installation of the software.