140H cat

[Nige]

Lewis, you're coming at this the from the wrong direction. The fact that you lose 2nd, 3rd, & 6th speeds points to the solenoid valve for #2 clutch is not working all the time because as you posted previously sometimes those transmission gears work and sometimes they don't.

There are only 3 possible reasons for this and you have already eliminated one of them - the solenoid coil, by swapping it with another one but the problem stayed where it was.

The other possibilities are:-

1. The mechanical part of the #2 solenoid valve could have an intermittent fault. If you have not already done it yet try interchanging the complete solenoid valve from #2 clutch station to a different location and see if anything changes.

2. You have an intermittent wire harness break somewhere between the Power Train ECM and the transmission control valve. The only way to find the fault is to locate all the harness connectors between the two components and disconnect every one of them. I don't have the Electrical Schematic in front of me right now but you need to identify the wire numbers that feed and return the voltage from the ECM to the #2 solenoid and using a digital multimeter to check the continuity of those wires in each section while someone else pulls that section of harness every which way to try to open up the broken wire. Once you have checked each section separately then start connecting the sections up one by one repeating the "pull test" each time you connect something. This is especially true of the connectors themselves. A corroded pin or one that is not 100% fully installed will also cause an open circuit, so give the connectors a good pull while testing for continuity. I'm pretty sure that you will find the fault somewhere in that section of wire harness.

 

[Mark250]

especially check the harness through the articulation area this is always a suspect area due to flexing and all the hard ware that passes through this area
Mark

 

[Nige]

Also I should have pointed out that to engage any particular gear in the transmission requires 3 clutches to be engaged. Your symptoms only point to a problem with one specific clutch - #2. Therefore it is highly unlikely (pretty much impossible TBH) for a problem in the transmission control selector in the cab to produce your specific symptoms.

 

[Rauf]

I have a problem with my machine..it moves and stopped,now no gear is moving again...what can possibly cause that.

 

[Nige]

I have a problem with my machine..it moves and stopped,now no gear is moving again...what can possibly cause that.

Potentially many things can cause it.
What machine model is it.? Serial Number.?
What have you looked at so far.?

 

[Rauf]

Potentially many things can cause it.
What machine model is it.? Serial Number.?
What have you looked at so far.?

The machine is caterpillar grader 140H,so far I checked for broken cable and found one cable broken.The cable was replaced and the machine moved for about 500 meters and stopped again and no gear was moving.we later re arrange the position of the solenoid and now only third gear for forward and reverse is working.

 

[Justimpactak]

Was there ever a resolution to this concern? I am having the same problem. No 2nd, 3rd or 6th forward gears. I have zero PSI on clutch #2 port with tandems raised in the air in 2nd or 3rd gear at idle as well as only 5V at solenoid. tried swapping solenoids and plungers no change. will check wiring in the morning just wanted to double check. If i have only 5V at solenoid it indicates an open?

 

[Nige]

Was there ever a resolution to this concern? I am having the same problem. No 2nd, 3rd or 6th forward gears. I have zero PSI on clutch #2 port with tandems raised in the air in 2nd or 3rd gear at idle as well as only 5V at solenoid. tried swapping solenoids and plungers no change. will check wiring in the morning just wanted to double check. If i have only 5V at solenoid it indicates an open?

Please can you provide some more information.

1. Is your machine also a 140H.? Serial Number.?
2. Have you checked the oil for a burnt smell and inspected the transmission suction screen to rule out the possibillity of a mechanical problem.?
3. Do you have an electrical schematic.? You're probably going to need one.
4. When you say "solenoids and plungers" I assume you mean that you swapped the entire solenoid valve assemblies between clutches, not simply the coils.?

Try reading through this THREAD, especially in regard to harness testing options (test light vs multimeter). It may give you some ideas.

 

[Justimpactak]

Please can you provide some more information.

1. Is your machine also a 140H.? Serial Number.?
2. Have you checked the oil for a burnt smell and inspected the transmission suction screen to rule out the possibillity of a mechanical problem.?
3. Do you have an electrical schematic.? You're probably going to need one.
4. When you say "solenoids and plungers" I assume you mean that you swapped the entire solenoid valve assemblies between clutches, not simply the coils.?

Try reading through this THREAD, especially in regard to harness testing options (test light vs multimeter). It may give you some ideas.

Thank you for the reply Nige, the Machine # CAT0140HAAPM01458
- I have aces to CAT SiS for diagrams however not crazy about the website.
- when back probing the solenoid connector with the machine running and in 2nd gear using a multi meter in only get 4.5-5.0V
- I will try my 24V test light when I check the CKT from ECM to solenoid.
-Yes I swapped the electrical portion first and then the plunger portion second with no change. Also bench tested coil and i was able to energize it and get a magnetic charge.
-Fluid is a little dirty it could use a service but doesn't smell burnt. I am trying to rule out the controls before I determine the tranny is at fault. Due to the nature of the failure.

 

[Nige]

-Fluid is a little dirty it could use a service but doesn't smell burnt. I am trying to rule out the controls before I determine the tranny is at fault. Due to the nature of the failure.

TBH the first thing I would suggest is to drop the oil into a clean container (don't dump it at this point - you can always put it back again to continue testing) then pull the screens, there are two of them, and inspect them for burned up clutch friction material. You need to rule out the possibility of a mechnical clutch failure before moving on to the electrical/electronic system.

I just sent you an electrical schematic. Check your message inbox.

 

[Nige]

when back probing the solenoid connector with the machine running and in 2nd gear using a multi meter in only get 4.5-5.0V

What voltage do you get across the other two solenoids that should also be energized with the selection of that partiuclar speed in the transmission.?

 

[Nige]

I will try my 24V test light when I check the CKT from ECM to solenoid.

Check what amperage your test light consumes. Some of them are only of the order of 0.5A. You need something between 3-5A to sufficiently load any circuit just to make sure there is not a wire hanging on by a thread somewhere.

 

[Justimpactak]

What voltage do you get across the other two solenoids that should also be energized with the selection of that partiuclar speed in the transmission.?

When checking all 3 of the solenoids that are activated in 2nd gear i get 4.5V on #2 and 23.5V on #4 &#7 when looking at the wiring diagram it shows 2 different resistance specifications for the different solenoids #2 is 8.5ohms and #4 & #7 are 31ohms double checked them with my meter they are with in spec. just not sure about the voltage being split like that but it does make sense base on the different ohm spec. I use a 24v incandescent test light that is aprox. 15ohms of resistance with a meter, so at 24V when load testing a wire it is about 1.6amps and 38.4 wats. Ill find a bigger bulb and retest again just to be sure.

 

[DieselFit]

Quite a few years ago on a 140H I had partial pressure loss on one clutch because there was a crack in the aluminium galleries of the valve body. There was an updated valve body available at that time. Generally the problem I find is a broken wire in the harness near the hitch for either the supply or return to a solenoid coil.

 

[Nige]

Generally the problem I find is a broken wire in the harness near the hitch for either the supply or return to a solenoid coil.

There is also a short harness (#1 below) actually mounted on the transmission, the one that feeds all the solenoids. The insulation on the wires of that harness tends to go hard over time and cracks, allowing oil into wires & connectors. Also the wires tend to fail where they are crimped to terminals in that harness.