Does anyone know how to access the clutch pack on a cat 420D. I can’t get the AWD to engage and have power going to solenoid Thanks
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No guarantees but with a full S/N might be able to find something on SIS. There are at least six different S/N prefixes showing and who knows how many versions with-in each of those!
Serial# CAT0420DVFDP07754
Have you checked the electronic transmission control for any faults.? It might be worth it before going any further. To put the transmission control into diagnostic mode requires the Harness Code Plug to be disconnected. You will find this in the battery box. It is a 2-pin Deustch connector with two Black wires (281 & 202) coming into one side and a short loop of black wire on the other. See below. With the key off, open up and remove the RH half of the connector with the wire loop on it. Put the key on and the indicator on the transmission control should start to blink. Use the table in the attachment to decipher what Diagnostic Codes may be present in the control. If there are no Active Codes the indicator will simply blink "11". The control is located as shown. Report back with your findings.
There’s no wires anywhere in the battery box. Just the battery and the hot and neutral hooked up.
Find the transmission control and the Harness Code plug won’t be too far away. I was only going by the electrical schematic that indicated it was in the battery box.
It's #5 on this illustration. Right next to the trans control.
I can not find the tcm anywhere on this thing… I’ve spent 2 hours looking
Just checked your Serial Number again. Your machine has a Direct Drive transmission and so does not have the autoshift transmission control. I looked at it once before and it came up as an autoshift transmission which is why I suggested checking the TCM - I must have got the S/N wrong. My apologies.
No worries. Do you have the sis on the process of how the 4x4 engages. I know the switch energizes the solenoid which magnetizes the coil and send pressure to the transfer case but don’t know if it’s internal pressure or some sort of hose
Here's the SysOp for the 4WD transmission. Have you checked the resistance of the 4WD solenoid coil.? The spec is 10.5 ohms. It's in a table on Page 10 of the schematic.
10 ohms on solenoid. I unscrewed the valve and put the solenoid around it cut the switch on I didn’t see and parts moving in the valve. When I purchased the backhoe the fuse would always blow when the fwd switch was cut on. Come to find out the solenoid was bad ever since I changed it I can’t get the fwd to work. But it has also hasn’t worked since I purchased the unit
I'm replying here and not the new post you put up to keep things in one place. Here is a screen shot of the diagram Nige sent you above: I zoomed in on the image to show the clutch pack that works the front axle that would be the item #16 in the image. I also added the red arrow that points to the oil line that supplies pressure to apply the #16 clutch. I'm thinking that if you pulled the o'ring plug out of the end of the housing just above there you should be able to install a pressure gauge and see if you are getting any pressure when machine is put into four wheel drive.
If this line is external I believe it’s a copper line that goes directly beside the solenoid on top of the transmission to the bottom directly to the transfer case. There’s no fluid coming out of this line when awd is engaged. Unless this line is internal.
https://spare.avspart.com/caterpillar/sebp2886/sebp2886028/#SEBP28860289 Reference line item#19 that’s what I’m thinking sends the fluid when switch is cut on
Do you mean 119? I'm attaching a couple more files one being how to pressure test the four wheel drive clutch.
No pressure on test port. Found the hydraulic diagram from the pump. The pump feeds the awd forward and reverse solenoids there’s a system relief valve in between the the solenoids gonna change this out to see if the pressure changes
There no pressure on the test port after changing system relief valve? Anyone know what could cause no pressure?