Caterpillar 140H transmission problem

[syncropete]

Having a problem with a 140H grader. I am sure its a simple fault but I cannot access SIS right now to give me an idea of pressures etc. Its a basic 5HM machine with mechanical pump on 3306. I have run ET and it shows only VHP solenoid as being high current. The machine will select all gears when the wheels are raised in the air (suggesting signal to solenoids is ok) but if you put it back on the ground it will only drive in gears 5678 forward and 456 reverse. In these gears it has plenty of drive and in the non working gears the machine will move very slightly. The oil looks clean. I am not sure how the transmission is configured internally but I am almost certain that somebody will be able to tell by the gears that are working. The valve block has been dismantled before from what I can tell. Any help would be much appreciated as here in Sierra leone I am pretty much alone and being a VOLVO trained fitter is not helping right now. Thanks in advance.
Pete

 

[kbeen]

syncropete did you get your answer to any of your questions? if not i can look in my book when i get to my office monday. i think there may be a common solenoid or clutch that can cause your problem. the M series transmissions engage 3 clutch packs at a time to give the different speeds and directions. if you loose pressure on just 1 of the 3 clutches the machine will not pull when under aload but will still turn the wheels in the air. you may have a bad solenoid, bad clutch or a stuck valve. let me know if you need more info.

 

[kbeen]

syncropete i did look in my book and the #7 clutch and the H- solenoid are in common with your problem. if you loose the H solenoid or #7 clutch pack you would have the symptons you are having. you could have the valve spool for the H solenoid stuck. if possible you need to check the pressure on the H solenoid. good luck.

 

[rare ss]

before you go too far in troublshooting, remove the side covers and clean ALL the trans electrical harness plugs/connecters for the solenoids

 

[droucom]

I have a similar problem, I'm trying to repair a 140H CCA, and there's no voltage in the coil number 8. So the machine only works on 1,2,3,4 forward, and 1,2,3 reverse. I was revised all the wiring from ecm, and there's no voltage on the line of 8 coil. Any suggestions??
Tnks in advanced.
David.

 

[kbeen]

Hello droucom, how are you checking for voltage at the solenoid wires ? are you un-plugging it and then testing for voltage. if so you cannot do that as when it is un-plugged the voltage will go away but you might see a 5 volt reference voltage coming through the wires. this is a floating voltage that the ecm sends down the wires so you can tell the wiring is good if you see the 5 volts. you have to check for system voltage with it plugged into the solenoid.

 

[droucom]

Hello, thank you for answering, I'm checking with connectors plugged. I was inspected continuty of the wire from ecm connector to coil connector, and it was good.
I think the problem is at ecm, but I has never used ET, and I haven't the adapter to use it.

 

[D&GExcavating]

I had the opposite problem with my 163H. It would only go through gears 1-3, but it wouldn't go into 4-8. Cat came out and had to change out a solenoid on the transmission.

 

[kbeen]

droucom they had quite a few problems with the gear shift control in the cab. it may be possible that the shift control is not telling the ecm that you are wanting voltage to the #8 coil. do you happen to have another machine there ? if so try swapping the gear shift control, and you could even swap the ecm if want to check it.

 

[Rafik79]

Good day. I have a problem on my 140h spool or port 8 is not giving me pressure. What could be the problem. Please help
Regards
Rafik

 

[Rafik79]

Hello. I have a problem on my 140 h the H spool
Or port not giving me any pressure.what could be the
Problem. Please help
Regards
Rafik
Mail me master.construction1@gmail.com

 

[kbeen]

First you would see if you are getting voltage to the solenoid for that H spool. you will have to test the wires with them plugged into the solenoid. if you un-plug them from solenoid to test them the ECM will not send any voltage down the wire. If you are getting voltage then you may try swapping that solenoid with another one. if still no pressure the spool in the valve could be stuck. see what you find out up to this point. good luck.

 

[Rafik79]

Thanks a lot kbeen will try and let u know
Regards

 

[Rafik79]

Good day kbeen I'm now getting pressure
On all the ports and tried the grader yesterday
It worked perfectly with all gears working
But today when we tried again gears 5 6 7 8 are
Not working. What could that be.
Once again thanks a lot for your advice
Regards
Rafik

 

[Jfarris]

We've had the same problem with our 143H over the course of 12 years. Both times it was the shifter in the cab needed to be replaced. Hope this helps.

 

[simonsrplant]

Did exactly that on a 140H today, turned out to be #4 coil burnt out, which had cooked the ECM. Et detected short to ground when connected to a serviceable coil. Swapped coils and ECM from similar machine, worked. New coil and ECM ordered.

 

[kbeen]

Hello Rafik79 I believe gears 5 6 7 8 all use a common clutch pack which if it was not engaging it would cause what you have. I can look in my book when back in office , let me know if you want me to.

 

[Cmark]

Did exactly that on a 140H today, turned out to be #4 coil burnt out, which had cooked the ECM. Et detected short to ground when connected to a serviceable coil. Swapped coils and ECM from similar machine, worked. New coil and ECM ordered.

This is a fairly common thing. Usually the Cat ECMs are fairly bulletproof with regards to open and short circuits but the designers seem to have missed a trick on these. I've probably had to replace maybe 20 ECMs in my life but I would guess around half of these were on H series graders for exactly this fault.

If I get a tranny coil go down, I'll usually replace them all at the same time. They're only around 20 bucks apiece and cheap insurance at that.

It also pays to check the harness for rubbing where it goes through the hitch.

Also be aware that once you flash the new ECM, if your machine has autoshift and VHP you'll need factory passwords to enable these features.

 

[Queenslander]

If I get a tranny coil go down, I'll usually replace them all at the same time. They're only around 20 bucks apiece and cheap insurance at that.

Cmark,
Do these coils usually present with any symptoms before throwing the towel in?
Our CCA sometimes fails to pick up, say, 2F after shifting from 2R.
Shifting back to reverse and trying again usually solves the problem.
It also hesitates slightly when shifting from 4th to 5th, but this might be normal.
Cheers, Greg

 

[Rafik79]

Good day. I'm getting very low pressure on
Transmission supply pressure tap on my 140 h
Grader. Recommended pressure is 479 psi
But I'm only getting 60 psi. What could be
The problem. Please help