Cat IT28F no reverse

[Tenwheeler]

It is serial number 3CL01750.
Any good advise on a manual? I bought one online but it ended up being a parts not service manual.
Any other input also appreciated but I usually like to start with a manual.

 

[Nige]

I’ll dig up some info on Manuals, and an electrical Schematic as well.

Meanwhile have you taken a look at the transmission screen(s) for clutch material and does the oil smell burned.?

 

[Tenwheeler]

That will be great!
No Sir I have not. I only committed to redoing the bucket pins and bushings. Then the contract hauler said it would not move in reverse after he drove it off the trailer.
All help appreciated!

 

[Nige]

Sent you the electrical schematic.
Here's the magnetic screen setup. 3-bolt cover on the bottom of the transfer case. I'd having a smell of the oil as a first step and if it had any sort of burned odour I'd be into that screen next.

 

[Tenwheeler]

THANK YOU for your help!
Oil smells like it has been hot but I do not consider it burnt. Coin toss?
I find three solenoids on top of the valve body and two under it. One to the front and one to the rear. In F gears a wrench will stick to several of them. In reverse it sticks to none. Used your diagram and found no power to the wires for solenoid 2 on the steering column wiring harness. Took me a bit to wrap my head around this wiring harness format. Then I found it odd it must all be powered off the power from the key switch which I thought would be only for the neutral safety switch. That way is to simple and not normally allowed from other manufacturers.
Called to order a new switch. That is a $1000 cowboy! Whoa! Want to double check what I am doing. Took the switch apart and found a loose screw. It has been out so long the head is worn flat. Nothing to do with my problem. It is a block of solid molded stuff with wires coming out of it. The shaft in the center does not turn. The plastic toggle has no connection to anything. It must have a magnet to function? Going to sleep on this one and go back to it tomorrow.
Any ideas appreciated.

 

[Nige]

Oil smells like it has been hot but I do not consider it burnt. Coin toss?

Without a physical inspection of the transmission screen it's impossible to tell either way IMHO. If it smells to have been hot then I would assume a fried clutch UNLESS there was nothing in the way of burned clutch material in the screen.

I find three solenoids on top of the valve body and two under it. One to the front and one to the rear. In F gears a wrench will stick to several of them. In reverse it sticks to none. Used your diagram and found no power to the wires for solenoid 2 on the steering column wiring harness. Took me a bit to wrap my head around this wiring harness format. Then I found it odd it must all be powered off the power from the key switch which I thought would be only for the neutral safety switch. That way is to simple and not normally allowed from other manufacturers.

There should be 6 solenoids (Fwd H, Fwd L, Rev, 1, 2, & 3).
All Cat transmission shifters AFAIK are powered only when the key switch is in the run position. Let's face it without the engine running you don't need the transmission so why would the shifter ever need power with the key in the off position..?
HINT: The Colour Reference Chart located at Grid C-15 on Page 2 of the Schematic might be a help to you.


Time to break out the DMM methinks.

 

[Nige]

........or switch the REV and the FWD Low solenoids. See if the problem shifts from being no reverse to being no forward. That would rule out the solenoid valves in the transmission.

 

[Tenwheeler]

Removed the screens. Contamination does not appear bad nor does the smell. Screens are bent from in proper installation so I ordered new ones.
When the REV and FWD Low solenoids are swapped, the wires were not unhooked, it goes backwards in F and nowhere in R.
The gear selector- direction control switch is new.
I still find only 5 shift solenoids and no Data Plug.
Will go back to testing wiring.
Suggestions appreciated.

 

[Nige]

Sorry, I should have been clearer with the instructions. When you swapped the REV & FWD LOW solenoids you should have also swapped the electrical connections for the two solenoids as well.
It took me a bit to get my head around it, but but based on what you reported above I would say that your REV solenoid is toast.

 

[Nige]

Forgot to mention. If you buy new I would suggest a complete valve, not just a solenoid.
The Part Number is 186-1525, price shown as $162.

 

[Tenwheeler]

I will check that out. Thank You!

 

[Tenwheeler]

Sorry, I should have been clearer with the instructions. When you swapped the REV & FWD LOW solenoids you should have also swapped the electrical connections for the two solenoids as well.
It took me a bit to get my head around it, but but based on what you reported above I would say that your REV solenoid is toast.

I understood what you meant. Someone cutout the factory connector for the forward low solenoid so I changed up your program a bit. Today I swapped the original reverse solenoid with forward high and all wiring as I first saw it. Unit has no reverse and solenoid is never magnetic. Forward high is magnetic in F4.
Then I removed the connector from the GP shift module as I thank it is called. I have connection between solenoid wires and the module. When the module was hooked up I had connection between one of the wires at the R solenoid connector and and 922 wire which connects to the gear selector switch. My notes list it as BR but it is black. Did I screw that up? Will look into that after the post. I had connection between the 922 wire for the selector and the module. Did not have connection between the 752 wire at the selector and the 752 wire at the module. I installed probe pins in the back side of those connectors. Volt meter reads 27 volts between them when everything is hooked up and running. Selector in R1. I installed a fused jumper between the two connectors and still no R. Then I checked voltage. 0 on 922 and 752. Then I connected one volt meter lead to power and both wires read 27 volts?

 

[Nige]

Here is the solenoid and clutch activation chart. I think it will help you.
Also if you need to check the transmission solenoids the resistance of the coil on all of them should be 33.8 +/- 1 ohm.


I would suggest that you go looking for numbers on all the wires.
Generally the only black-coloured wires in a Cat wiring harness are ground wires.
The transmission solenoids do not work using a conventional ground, they have a "supply" and a "return" wire.
Is there any chance you have crossed the 202 Black Ground wire to the transmission control with one of the solenoid wires..?
I'd also suggest to go looking at the connectors between the transmission control and the cab firewall - there are two of them, one at Grid D-6, the other at Grid B-9.

 

[Tenwheeler]

Today in a little better light I see the 922 wire is brown. I will look in to it some more. Thanks for the help.

 

[Tenwheeler]

Had wiring problems in the harness under the right windows in the cab.
Thank you for your help.

 

[Nwufor]

Had wiring problems in the harness under the right windows in the cab.
Thank you for your help.

How did you solve this problem please...am having thesame problem