Service 4x4 message and C1464 and C147B code

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bart_r6

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Caledonia ON
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2018
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5.7
Hey Guys,
Really need some help here trying to figure out my 4x4 issue. I have a 2018 ram 1500 and a few weeks ago a "service 4x4" message came up on my cluster and ever since then I'm not able to shift into 4x4. I have read and searched a lot of posts trying to figure this out but I'm stuck and dont know where to go from here. During the last few weeks I have done and found the following:
1. Because of C1464 and C147B all the posts I have read said to replace the front axle lock actuator. I took one off my other ram and swapped them and still nothing. I cleared the codes and they came back right away withing 2-3 seconds of clearing them. I know my actuator is good because it worked fine in the other truck. When I try to select 4 lock or 4 low nothing happens and the led light does not illuminate next to those 2 buttons.
2. I checked the plug connector and it also appears to be good and all 4 wires are in good shape.
3. I checked the voltage at the plug while it was disconnected from the FAD and I get 11.2V at pin 3 and 4.05V at pin 2. The ground at pin 1 was also checked and is good. Just for reference the voltage at the battery was 12.4V while checking the output at the plug. After checking the voltages with a voltmeter I also used a test light as was suggested in one of the posts I read but it did not illuminate at all even tho I was getting 11.2V with the voltmeter. I think this might be an issue but dont know what to check next.
4. Checked fuse 77 which was good as well as I took out the entire fuse box and inspected the wire harness connector plug which was located underneath and everything looked good there....no corrosion or broken wires at the connector.
5. One thing that I found while trying to trouble shoot this whole thing over the last few weeks is that currently the truck is stuck in 2WD. When I go under the truck the shaft between the front diff and transfer case is free and i can turn it by hand. In this situation when I scan the DCM for codes I only get the 1 code C1464. Now when i go and clear the code I have 2-3 seconds when the service 4x4 message dissappears from my cluster and during that short time if I hit the 4x4 lock button the transfer case will actually allow the truck to shift into 4x4. When i try to move the shaft connecting the transfer case and front diff now its solid and I cant turn it by had anymore. So now the cluster has the 4x4 symbol illuminated on the right side plus the 4x4 lock led light is light up on the button and when I read the codes now I get the C147B code. The original code C1464 is gone in 4x4 mode. As soon as i go to clear the code ...same thing happens ...I get 2-3 seconds before the service 4x4 message comes right back up on the screen and i'm unable to select 2wd or 4low. The only way to go back into 2WD is to clear the C147B code and while I have that 2-3 seconds when the scanner is clearing the code i can press 2WD button and truck will shift and go into 2WD. At this point i'm locked out again from shifting into 4x4 and we get the original code of C1464 while scanning when 2WD is selected.

Sorry for the long write up but i wanted to provide as much info as possible for someone here to point me in the right direction what to do next. In 2 weeks I'm going way up north for a snowmobile trip where having a functioning 4x4 truck is essential so I need to figure this out asap please. Going to the dealer is not an option as the truck is out of warranty because of the milage. Any and all help would be greatly appreciated.
 

BLK-9

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Did you ever get a response to your post?
 

Mg2520

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I’m having the same issue. Checked the fuse replaced the actuator brand new part. Cleared codes disconnected the battery to reset nothing has worked so far. I’ll be watching the thread hopefully we can both get solid repair advice here!
 

skydog

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EcoDiesel 3.0
Having similar issues here on a 2016. Anybody have a diagnostic/fix for this?
 

Mg2520

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I haven’t found an answer but looking further I saw something about possibly needing to reset the computer after replacing some things beyond just a battery disconnect reset like a factory reset so I went to a dodge dealership and asked them to do a reset they said they were unable to get the computer to reset they would need a couple days to troubleshoot I haven’t had the days to give up the truck yet. But maybe a computer issue ?
 

skydog

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Update: spent the weekend under the truck -18c. Came across a dated but very useful trouble shooting procedure for the C1464 and the C147B codes (attached). Was able to determine I had a short to voltage on the G303 circuit and lost continuity (intermittent) with short to voltage on the G304 circuit. Both were acting funny and changing, Sometimes a continuity issue, sometimes a short to voltage. Unplugged the connector at the wheel well and diagnosed for both conditions back to the PTCM and found no faults. Did the same from the wheel well connector to the FAD connector and ran into same issues, basically lost continuity on G304.

I peeled back the tape and sheathing at the FAD connector to expose the wiring and found the G304 (VT/DB) wire pooched and because they were so tightly twisted together, the G303 (VT/DG) wire insulation was also compromised. Barely had enough wire to do a shunt with solder and heat shrink as a temporary measure. when the weather warms up, I'll de-pin G304 and G303 and re-pin properly.

It was that easy and that complicated. I wish I would have come across the diagnostic procedure sooner rather than throwing a new t-case shift motor and a FAD module at it. Live and learn.

Very happy to have my 4x4 back. :cool: If you're reading this post with a similar problem, I hope this helps you out.

Cheers,

Skydog
 

Attachments

  • C147B 4X4 Diagnostic.pdf
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Mg2520

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I found my issue at least I hope maybe it helps someone else. I used a dorman replacement for the actuator. A couple weeks after I had a turn signal plug that needed to be replaced I used a dorman plug it didn’t work reading around I found someone who mentioned dorman might not work the computer for some reason wasn't reading it I changed to another brand and it worked just fine. It’s been a while of just accepting I either had a 2wd truck or I was going to have to get some cash together to drop it off to dodge. I thought maybe I was having the same issue with the actuator as I was the turn signal plug changed it out with another brand and works great! I used the standard ignition the second time.
 

RoddyO

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Hey all, new to the forum but thought I'd share my experience. My buddy was having intermittent 4WD issues and upon inspection, right where the harness is clipped in with the brake line and abs right by the frame, approximately 6-8 inches away from the disconnect module, the ground wire was broken. Soldered the wire and he's all good now.
 

mxracer72584

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Midland, MI
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2014 2500
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6.7 Diesel
I recently had this issue, service 4wd light on, C147B code, got stuck in 4wd. I checked continuity of the 4 wires through the jumper harness to the front axle actuator. From the connector at the disconnect, to the other end of the jumper harness, which is up behind the right side of the front bumper, attatched to the front body mount frame bracket. I found I had an open ground wire, sure enough, about 6 or 8 inches up from the axle disconnect, the loom was broke, and the ground wire was broken as well. I assume from cycling/movement of the front axle. Repaired the wire and all is good again. Thank you to Skydog for the information you posted on your issue, it helped me repair mine as well.
 
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