I have a 2002 jd 755c that was working fine and sitting for months. I tried to start it , but the batteries was dead, and accidentally jumped cable in a wrong way( wrong polarity). After installing a new batteries , the engine starts and runs fine , the bucket goes up and down fine, but the transmission is not actuated . The red light doesn’t go off after releasing the two brakes. Please, any ideas what I need to looking for the parts that could be damaged? What would be the likely damage caused by wrong jump cable. How likely is the TCU get damaged ?
Did you check for a fuse to the TCU? Some have a transient voltage protection module to catch issues like this. You will need someone to find out which wire is the positive supply to the TCU. Back probe the wire at the TCU plug with a sharpened paper clip(slide the sharp end of the paper clip along the wire under the silicone seal until you hit the metal crimp terminal inside the plug- do not pierce the wire insulation!). You should have 24V between the paper clip and ground.
Welcome to HEF Abukee ! First a serial number. The way the wire loom is on the harness you will not be able to backprobe the TCU connector to check your voltages. Like Questionable said check your fuses. Is your emergency shutoff pulled out? What indicator lights are on with the key on engine off? Then start the engine and tell me "exactly" what happens with your Travel Range indicator light and your Electronic Fault system indicator light when before you lift the park lock lever and after you lift the park lock lever.
Thanks guys, The serial is LU755CX005296. I found out the the warning light relay( K10) was bad, so I changed it. Now the electronic fault indicator light will go off , after the park brake lever raised up and park brake released.No other lights is on , but the park brake light was not working before the incident(was not turn on and off).But now the machine won’t start moving( travel function is not actuated). Before the relay replacement, I changed the pressure switch -B5 that didn’t make difference on the warning light.Hey mg2362, to your specific questions , I will double check and update it. I really appreciate ur responses, thanks a lot.
I just found that with the key on, these lights are on: park brake , transmission/hydraulic oil pressure, low travel speed range, and electronic system indicator. With engine running,park lever raised , and park brake released, all the lights will go off except the park brake light. The park brake indicator light stays on , and looks like the brake won’t be released.Please, any suggestions what to check on. Thanks a lot.
The park brake light will remain on until the FNR is moved, not when the park lever is raised. When you raised the lever did the range indicator light (L) flash one time?
It doesn’t flash, it just turns off with the lever raised. I see the same thing with the electronic indicator light.
If the "L" light does not flash then the most likely issues are either the travel lever is not in the neutral position or one of the steering/brake pedals are not in the minimum position OK voltage specification. Make sure there is no dirt accumulation around the pedals to prevent them from returning to the up position. How handy are you with a voltmeter?
Not that much bad, I will try. Thanks
If you backprobe (being careful to not damage the terminals inside, use a small pin) the steering pedal connectors at (I think) terminal #2 and measure the voltage at the various pedal positions (pedal up, pedal down) and post. The center pedal also needs to be checked at terminal 2 (I think again ) and check pedal up, pedal down where you feel resistance and pedal all the way down and post. Since you cannot move right from the get go I am most concerned what your voltages are with the pedals untouched (all the way up).
Oh man , it turn out that TCU is bad. With swap of other same machine of TCU, the machine moves. Any place to get it rebuilt? Thanks