Greetings everyone. First time posting on your forum but have visited many times through the power of google. But this machine im working on is majorly F-d up and my boss refuses to call John Deere so. Its a 624G last Thursday machine wouldnt go into gear F or R so the day laborers put a gear selctor switch in, ran great till they shut it off. Friday I go there right from home armed only with a test light. Poke around and wasnt getting power out of parking break switch, swapped switches from sister machine, worked great. Shut it off same thing. So yesterday swap the TCU, nothing. All the fuses are good, swapped relays. Ohmed out the solenoids, nothing. Clutch disconnect works, no power when engaged, power when disengaged. The parking break does dissengage freely as well. What I did find though is the tranny temp sensor is bad but jumped it out with my power probe and a 9v, nothing. Getting power to the TCU but nothing out of it for the drive solenoids. When I power the soenoids works. I am just racking my brain and wondering if I over looked anything or anyone have any experience with these machines. Thanks in advance, Jon
Would say the TCU is seeing a short somewhere & shutting off. Those early ones are terrible to diagnose. When you power on ignition, should hear 2 clicks from TCU, a third is it shutting off because of problem. If it's not shutting off, it's probably something to do with park brake.
3 clicks from the TCU. I am short on literature for this machine. Anyone have any test procedures or diagnostic flow charts for this machine?
TCU is shutting off because it detects a short, I would start unhooking things & listen to tcu. Most common place for me was where the harness goes into valve body on trans.
What is the TCU ie Funk, ZF, Clark/hurth(Spicer) I might have some information on the wiring
Should be ZF.
Is it a EST-19 ? It would have a 35 pin connector only 18 and 35 are ground(frame) solenoids should be 10 to 25 ohms to ground. ohm meter with power off
As far as I know ZF usually fitted an EST17T or EST25 TCU for 24V, EST19 for 12 V system. Is there a TCU no. available? Did you ever swap the gear selector? TCU needs a permanent feed for N, F and R depending on position of switch.
I've got access to a 624G service manual, I'll take a look and see what I can dig up when I'm at the shop on Tues
The TCU I was give is an EST-26 want to check what I took out of it originally. The gear selector is brand new. Gonna try plasters today for a manual
Hello Thatguy88, I have a general electric diagram for EST26 available. Please come back to [email protected] . br
I checked the manual I have, it's the repair manual TM1530 and doesn't have any troubleshooting or electrical diagrams/specs. You're needing TM1529 Operation and test. The system is very basic on these older machines, shouldn't have too much trouble locating the problem once you have a diagram to work with! Cheers