ZF4WG-180 transmission problem

[ScottM1A]

Short time lurker first time posting.
We have a Dae Woo Mega 250 with a ZF transmission and about a week ago the guys were using it to load snow and parked it the next day when started up it wouldn't move. I've narrowed it down to an electrical issue the TCM has good power and ground inputs and current is going through the shift selector and into the TCM but isn't getting to the valve body solenoids. The failure seemed too be at the TCM so I took it out, opened it up and found a melted high current resistor or diode and burned circuit board. Ordered a new module from Doosan did a pin out test as best I could, I have a wiring diagram which shows me how current flows though the module but I don't have any info on what resistance specs are for the solenoids or whether voltage gets stepped down from the 24 v that goes into it and things seem normal and I don't have any obvious shorts to power or ground but the machine still won't move in any gear forward or reverse. Any ideas where I should look? As a special bonus temps have been mostly above freezing the last week and where it's parked has turrned into a mud bog.

 

[Bigbert]

Hi Scott
The solenoids (5) are supposed to have a resistance of 90 to 100 Ohm @ 20 degrees.
check wiring from TCM to control block, also cabine plug (where harness leaves cabine towards t/m), check plug at control valve, check internal harness (behind sheet cover, half liter of oil coming out))

br

Bigbert

 

[laycobeau]

Does your dash indicator show that you are shifting or does it stay in neutral? Also what is the EST model number on the TCM.

 

[ScottM1A]

Thanks for the replies.
Bigbert I should be okay there then because I had 84 ohms on all of them yesterday afternoon and it was probably just over freezing. laycobeau the machine doesn't have a dash indicator, the EST number is EST17T and is marked 24Vm, the ZF part number is 6009 054 248.
I also should have been more clear, power goes into the TCM but doesn't exit to power the solenoids. Example, if you want to drive the loader in F3 ign on power comes from fuse 6 to the shift selector and pin 1&2 of the TCM. With the switch in F3 power goes to pin 8 and then should move through the TCM and come out at pin 32 to go to the forward solenoid which is 3rd gear but it doesn't.
I either have a bad module which I would be surprised by because I went to the OE dealer or I've got a large voltage drop happening and when a load is placed on the circuit it acts like an open circuit. I'm going to use a jumper wire to bypass any multipin connectors in the rats nest under the fusebox and power the TCM and selector switch that way and see what happens before condemning the new module. I've gotten a bad module a couple times in the thirty years I've fixed cars and stuff but it's rare.

The melted part was a capacitor by the way not a diode it was just a newer style cap.

 

[Bigbert]

Hi Scott,

please come back with an email to hugo.burkhart@gmail.com. I can get you some more electrical details.
Will the TCU get power to the solenoids with control valve disconnected?

br
Bigbert

 

[ScottM1A]

I found the problem, there was some pretty severe corrosion inside the selector switch harness behind the steering column. There are three wires not two like I thought ( I was confused) and contacts that need to flow current for each gear choice and one had power until the circuit closed. I need to make certain tomorrow that the amp draw through the circuit is normal after cleaning the connectors but I got it to move forward and back after jumpering two connections and applying a power probe to the third. Hopefully it doesn't need the $850.00 switch too. My head hurts from beating it on this pile but I think I won.