Can someone help me understand why the machine only moves when I break the connection that has to do with declutching? The machine only moves when there is no 24V going to pin 22. Shouldn't it be the opposite? It only moves when there IS 24V going to the TCM? Indicating all circuits and safeties (brake pressure, parking brake, left declutch pedal) are working? A break would tell the computer to put the transmission into neutral? I cannot figure out why it is backwards right now. I am using a TCM from a Hyundai with the exact same programming (called ZF) but I don't believe Hyundai wheel loader would be the opposite since it is a ZF module still. Solenoids are all good, points on the TCM harness connector are all good, found broken wires at the speed sensor (now fixed), transmission fluid was low. Is it possible the computer is having issues because of a ground making it do weird things? Pins 18 and 35 are grounded good. Solenoid ground back to TCM is good (Pin 33)
On a Deere loader same vintage with ZF trans, anytime there is power at TCM pin 22, trans will not go into gear. Do you have a trans wiring schematic for the Case loader?
Thanks for the reply yes I have these. This is exactly how it seems to be set up, so when the TCM gets 24V it will not go into gear. I know the solution here is simple im just having trouble understanding it. The diagrams reads to me the opposite that when any one thing in the chain breaks the circuit (for example the parking brake applied) it should declutch the machine. But the opposite is true currently on this unit. When the parking brake is applied the machine will go into gear.
The “training“ schematic and the “21 series transmission control schematic” are in my mind not similar. . So we know that is not normal . Maybe one of the Case guys @Coy Lancaster has a schematic and can help you further.
I hooked up a relay for now so when it wants to provide 24V to the TCM it now cuts the voltage off, and when the safety switches voltage off the TCM gets 24V. It all works now, not sure why though. Case must be backwards than Deere and Hyundai loaders for terminal 22.
It sounds like pin 22 might be wired as an active-low input rather than an active-high one. On some ZF systems, the TCM expects that circuit to be pulled to ground (or see no voltage) to allow drive, and 24V on the pin means "declutch active" or "neutral request." A few things I'd check: Verify what pin 22 is actually supposed to see according to the ZF wiring diagram, not just the Hyundai harness. Check if the declutch switch is normally open or normally closed. Make sure the input isn't being backfed with 24V from a wiring repair or incorrect switch wiring. A bad ground can definitely cause strange behavior, but if pins 18, 35, and 33 all test good, I'd be looking at the input logic and wiring first. If the machine consistently moves only when pin 22 loses 24V, that almost sounds like the TCM is interpreting 24V on that pin as a declutch command rather than a "ready to drive" signal.
Sorry I meant this machine is a Case 721B. I found and installed a TCM from a Hyundai loader (ZF said the programming and shifts are the same). Pin 22 according to the Case electrical diagram, should receive 24V if all the safeties/switches are working correctly. The problem is the Hyundai TCM I installed appears to want 24V to declutch. I am starting to believe the Case/Hyundai are opposite on Pin 22 for declutching. The declutch dash switch is normally opened so the only way for 24V to get to the TCM would be through the declutch brake pedal switch. When you push the dash switch it bypasses the brake pedal and allows 24V into the circuit. I don't believe there is any back feeding as the circuit lines up with the diagram when things are switched on/off. Pin 18 and 35 are grounded good at the connector (unplugged), pin 33 is good to the solenoids but not ground (checked unplugged) I believe it is supposed to be a dedicated ground to the TCM so that should be okay.