Cat 143 H Trans no 1-4 in F or R

neutron75 · Nov 14, 2020

We have a 143 H at work it doesn't go into first through forth in ether forward or reverse and am wondering if anyone may have a starting point as to where to look its a state forestry grader so its lightly used only has 3700 hours on it it never alarmed on me till I got back to the shop with it the other day and I only realized the light going off when I made it back any help would be great thank you in advance for the help

Nige · Nov 15, 2020

neutron75 said:
We have a 143 H at work it doesn't go into first through forth in ether forward or reverse

Are you sure about the speeds you're missing.?
The reason I ask is that missing 1-4 in forward and 1-3 in reverse would all point at clutch #7 because it is used for all those gears.
Post a Serial number when you reply please. It makes finding the correct technical information easier.

Quick & dirty check. Pull the transmission dipstick.......
1. Is the oil black.?
2. Does it smell burned.?
3. Is the level correct as per the marks on the stick.?

neutron75 · Nov 15, 2020

Trans oil is clean not burnt and the right level. I'll get that on SN on Tuesday when I am back at work. I am pretty shore its 1-4 on both sides Ill have to check that too when I am there. can I get the codes for it with out hoking computer to it I had see some of the other posts in the grader forum about it I think one was a 140H and the other was a 143H if I can I'll get them Tuesday too

Nige · Nov 15, 2020

Clean oil is a good indicator of potentially an electrical problem with the engagement of #7 clutch.
Burned/black oil would most lkely indicate a clutch failure (transmission out time).

As I said above the only fly in the oitment is if your comment regarding 4th gear reverse is correct that blows the #7 clutch theory out of the water.

#7 clutch is only used for 1-4 forward and 1-3 reverse. It's the lower half of the range in both directions, remembering there are 8 forward speeds in the transmission but only 6 reverse speeds.

neutron75 said:
Can I get the codes for it with out hoking computer to it I had see some of the other posts in the grader forum about it I think one was a 140H and the other was a 143H if I can I'll get them Tuesday too

Dunno without having a S/No to check what the procedure is for getting Codes. I suspect it might need a Click Box. There is a thread on that in the Shop Talk forum and it is possible to McGyver something with nothing more than 2 pieces of wire and a couple of electrical connector pins.

neutron75 · Nov 15, 2020

Thank you Nige I will look at both when I get back to work. When I pulled the stick after it the oil wasn't hot or what I thought to be over heated

Nige · Nov 15, 2020

Here's a link to the Click Box thread. From memory I think the instructions on how to Mcgyver one are on Page 3 or 4.

https://www.heavyequipmentforums.com/threads/the-famous-cat-click-box.72956/

Nige · Nov 15, 2020

neutron75 said:
Thank you Nige I will look at both when I get back to work. When I pulled the stick after it the oil wasn't hot or what I thought to be over heated

So long as it is clear & bright that suggests there is a strong possibility the problem is electrical and external.

Mark250 · Nov 15, 2020

the last few posts explain how to retrieve the codes
https://www.heavyequipmentforums.com/threads/cat-143h-transmission.85097/

neutron75 · Nov 17, 2020

Hear is the build plate i am letting it warm up a bit before I try and see about the speeds on the trans

neutron75 · Nov 17, 2020

Just checked it it is 1 to 4 forward and 1 to 3 in reverse

Nige · Nov 17, 2020

OK, that makes far more sense. From what you posted before (oil not black, no burned smell - can you check that again plaease, especially the smell of the oil) it sounds like it could be something electrical failing to activate the #7 clutch solenoid.

Below is an illustration of the transmission control valve that is on the left side of the transmission. The 8 solenoids are mounted on the front (cab) side of the valve.
Solenoid G (Ref 7) is for the Low Range clutch. This gives you speeds 1-4F and 1-3R.
Solenoid H (Ref 8) is for the High Range clutch. This gives you 5-8F and 4-6R.
What I'd suggest is the following: -
1. Disconnect solenoids 7 & 8 from their respective electrical connectors.
2. Exchange the solenoids of valves #7 & #8. The solenoid can be removed without the need to remove the valve body simply by taking off the big nut #2 on the end (see below) and slide the coil off the shaft.
3. After exchanging the solenoids reconnect the electrical connectors to the appropriate solenoids - Don't cross them.

neutron75 · Nov 17, 2020

Is it solenoid G and H or H and D because its now missing different gears in both forward and reverse I know that they can do things different on different equipment the grader now seems to be doing the same thing as one in another post is doing

Nige · Nov 17, 2020

If moving the solenoid from G to any other position has now caused different gears to go missing then the solenoid you removed from #7 (G) is bad.
As a final check put the solenoid coils back where they were originally but leave the electrical connector for Coil #7 disconnected. Are you still missing 1-4F & 1-3R..?

If the answer is yes then you need a 301-3118 Coil Assembly. Should be about $30 from the dealer.

neutron75 · Nov 17, 2020

In forward I dont have 3,4,8 and in reverse I dont have 3,6 now

Nige · Nov 17, 2020

neutron75 said:
Is it solenoid G and H or H and D because its now missing different gears in both forward and reverse.

Out of interest which gears was it missing.?

EDIT: Sorry, answered above. That's no power to #5 clutch.

neutron75 · Nov 17, 2020

I'll let you know hear after a bit when I get back to it

Nige · Nov 17, 2020

neutron75 said:
Is it solenoid G and H or H and D because its now missing different gears in both forward and reverse I know that they can do things different on different equipment the grader now seems to be doing the same thing as one in another post is doing

You're right. I was going off a diagram posted on another thread that I was sure was the right one.
The low and high range clutch solenoids on your transmission are D & H.
As a check. You should have four identical solenoids in the inside row of the control valve closest to the transmission - #5, 6, 7, & 8 in the diagram above.
In the outside row the bottom solenoid #4 should be the same as the four on the inside row. The three above it should be identical but different to the other five.
Based on that solenoid H should be the bad one.

neutron75 · Nov 17, 2020

Alright I moved the bad one back to where it was and it moved back to 1 to 4 F and 1 to 3 R so I am going to say its the solenoid

neutron75 · Nov 17, 2020

And yep there are two different types in the block in the configuration you stated above thank you for the all the help these last fue days when we get the new one and put it in I'll let you know how it turns out thank you again

Cmark · Nov 17, 2020

If you're replacing a coil, I recommend you replace them all. They're not expensive and when they fail, they can sometimes take out the transmission ECM.

Cat 143 H Trans no 1-4 in F or R

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