Wiring harness damage troubleshooting

[12rounds]

Hi all,

First post on this forum, need some help.

I have a 2018 ram 6.7. I parked it last night after a day of work and this morning it won't start, in fact it seems like the computer decided that it's a manual at some point in time during the dark hours...too bad it didn't grow the associated shifter.

So, it's really an automatic - 68rfe - and I'm trying to figure out what happened to make the ecm freak out and change to the push clutch to start message instead of push brake to start like normal. I had been having some uconnect 8.4 touch issues, but nothing like the delamination that others have been having - mine was not responding to touch at all.

I tried to read codes, but the computer isn't responding to the can bus connection. There are also a bunch of new brake and trailer brake messages in the info center on the dash. I call up the dealer that I go to - the service advisor manager is a decent guy and usually helps all he can on the phone. He says that he remembers seeing this once before but can't remember the fix.

I'm worried that the PCM took a dump...since I don't want to tow the truck I check all the fuses and start googling. The concensus is the I should charge the battery and start looking for a loose connector or ground.

So, I find the problem: up under the dash in the passenger footwell there is a connector with 3 wires - white/blue, white/green,black - that has been chewed through by a rat I'm guessing. I repair the harness and the truck starts. Now, the ac is acting up - doesn't blow cold, blows from the wrong vent, and I have a bunch of stored codes that I can't clear and a permanent u0155 code. None of my 3 scan tools will clear the codes and im trying to see if I still have a wiring issue without having a wiring diagram to use. I think the wires are can bus positive and negative, but I don't know where they go or what to do next to see if there are remaining problems or if the codes will drop off after so many start cycles or how to clear the codes to see if they come back. Any help appreciated!

 

[SitKneelBend]

Hi all,

First post on this forum, need some help.

I have a 2018 ram 6.7. I parked it last night after a day of work and this morning it won't start, in fact it seems like the computer decided that it's a manual at some point in time during the dark hours...too bad it didn't grow the associated shifter.

So, it's really an automatic - 68rfe - and I'm trying to figure out what happened to make the ecm freak out and change to the push clutch to start message instead of push brake to start like normal. I had been having some uconnect 8.4 touch issues, but nothing like the delamination that others have been having - mine was not responding to touch at all.

I tried to read codes, but the computer isn't responding to the can bus connection. There are also a bunch of new brake and trailer brake messages in the info center on the dash. I call up the dealer that I go to - the service advisor manager is a decent guy and usually helps all he can on the phone. He says that he remembers seeing this once before but can't remember the fix.

I'm worried that the PCM took a dump...since I don't want to tow the truck I check all the fuses and start googling. The concensus is the I should charge the battery and start looking for a loose connector or ground.

So, I find the problem: up under the dash in the passenger footwell there is a connector with 3 wires - white/blue, white/green,black - that has been chewed through by a rat I'm guessing. I repair the harness and the truck starts. Now, the ac is acting up - doesn't blow cold, blows from the wrong vent, and I have a bunch of stored codes that I can't clear and a permanent u0155 code. None of my 3 scan tools will clear the codes and im trying to see if I still have a wiring issue without having a wiring diagram to use. I think the wires are can bus positive and negative, but I don't know where they go or what to do next to see if there are remaining problems or if the codes will drop off after so many start cycles or how to clear the codes to see if they come back. Any help appreciated!

This site will help you repair wires and identify the connectors...

https://connectorrepairkit.mopar.com/

In addition, I believe you will need a security bypass module adapter to clear codes on 2018+ trucks but I'm not positive.

 

[12rounds]

Any tips for how to pick my unknown connector pair out of that list?

Ordered a SGW module bypass. I really hate that I have to do that. God forbid I clear the codes on the truck that I own without permission from RAM.

The AC started to work normally again today. No idea why- I didn't change anything. Hopefully, I can clear the stored codes and they won't come back.

 

[SitKneelBend]

Any tips for how to pick my unknown connector pair out of that list?

Ordered a SGW module bypass. I really hate that I have to do that. God forbid I clear the codes on the truck that I own without permission from RAM.

If you can find what it's connected to you can then filter that list on keywords such as ECM, PCM, accelerator, brake, etc...Conversely you can take a guess as to what it is and see if the connector and wire colors match what is on the site.

 

[zrock]

if something has chewed those wires i will guarantee their is more damage elsewhere. Would almost bet as well that the damaged wiring has damaged one or more of the trucks computers. You should not need any special module to read and clear codes you just need it if you want to do programming changes

 

[12rounds]

If you can find what it's connected to you can then filter that list on keywords such as ECM, PCM, accelerator, brake, etc...Conversely you can take a guess as to what it is and see if the connector and wire colors match what is on the site.

This pair of connectors is weird - it the male and female plugged together in the passenger footwell, 3 wires in a 14 position connector: blue/white, blue/green, and black. It disappears in both directions behind a bunch of trim I didn't yet remove. I'll try and find it on that stellanis site, but the Haynes manual says those wires are CAN bus wires, but it calls them out in diagrams that aren't helpful and it doesn't have a complete set of diagrams...

 

[12rounds]

if something has chewed those wires i will guarantee their is more damage elsewhere. Would almost bet as well that the damaged wiring has damaged one or more of the trucks computers. You should not need any special module to read and clear codes you just need it if you want to do programming changes

Before a few days ago I would have agreed with you. I can clear codes in the scanner that are OBD2 codes, but as soon as I try to clear codes in the enhanced obd, ram specific obd, or other can bus modules like the BCM, it won't clear. This is apparently a thing started in 2018 with the installation of a security gateway module and another member on this site has created a bypass to allow write interface on the CAN bus to allow clearing codes in modules protected by the SGW module hardware firewall.

https://www.ramforum.com/threads/2018-ram-security-module-bypass.125133/

 

[12rounds]

Searched through the linked website to try and figure out what this connector is. Started off finding what 14 pin connectors were used and then crossing them to the year and platform. This is what came back and it is not what I have...
The connector is the same, but the number of circuits and wire colors is completely different. Any ideas?

 

[HarryS]

This is the right connector you're looking for.

 

[12rounds]

This is the right connector you're looking for. View attachment 546959

Thanks!!!!

I don't know what you entered to find it, but I appreciate it.

I don't suppose anyone has a schematic or diagram that includes circuit d64 and d65?

How does one even go about testing the can bus to see that it's within a basic tolerance? I saw an article saying that each wire should be in a certain voltage range - anyone know if this is true for all vehicles with a can c bus?

 

[mtnrider]

I don't suppose anyone has a schematic or diagram that includes circuit d64 and d65?

Here you go.... It appears it is inline with the powertrain control modules which might explain why the truck thought it was a manual?

 

[SitKneelBend]

This is the right connector you're looking for. View attachment 546959

Here you go.... It appears it is inline with the powertrain control modules which might explain why the truck thought it was a manual?


View attachment 547016

I love this forum...

 

[HarryS]

Thanks!!!!

I don't know what you entered to find it, but I appreciate it.

I don't suppose anyone has a schematic or diagram that includes circuit d64 and d65?

How does one even go about testing the can bus to see that it's within a basic tolerance? I saw an article saying that each wire should be in a certain voltage range - anyone know if this is true for all vehicles with a can c bus?

Welcome. Go to Amazon and purchase a cheap O scope. Should be less than 30 bux. https://www.amazon.com/FNIRSI-DSO15...21-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9tdGY&psc=1

With it you will be able to see if the can bus, or any bus is working.

 

[12rounds]

Here you go.... It appears it is inline with the powertrain control modules which might explain why the truck thought it was a manual?


View attachment 547016

Thanks!!! Do you have a higher res image? I can't actually read any of the words when I download it..

 

[12rounds]

Welcome. Go to Amazon and purchase a cheap O scope. Should be less than 30 bux. https://www.amazon.com/FNIRSI-DSO152-Oscilloscope-Automotive-Bandwidth/dp/B0C8N1ZV8Z/ref=sr_1_21_sspa?crid=WP4FGVYXXEJO&dib=eyJ2IjoiMSJ9.vHIy_rxKnHykr3H25U8V22BB7M4mFcb6j3TeNaheLDqQOG-pr03yNrEQx_3zO57zgKIhnA3F7S2Kb5Q8puy3EhoH2OgZGdkI5ItoRI1kQAZBvA_GEaIjXjb5XkfCLL75RA54-NEdCdnX64XK-eK0H7Q5iqUeYJ5xbEG7VNMrpGeMPr0QE78FTkieUQQIQMrXbgHl5v3Mv40RueqW78LAqoOSPaEGEKEvHGWArROQSos.6EQltPtxrl6AwhEtJQj7PRd_0TmNkDNR6GXED86gjyg&dib_tag=se&keywords=o+scope&qid=1721532543&sprefix=o+scope,aps,141&sr=8-21-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9tdGY&psc=1

With it you will be able to see if the can bus, or any bus is working.

I own an o-scope - but looking at a digital bus without having a reference is not super useful. That's why I was asking if anyone had any recommendations for testing the bus. Although, the truck is running and the cel is off, so this is probably a moot point...

 

[mtnrider]

Thanks!!! Do you have a higher res image? I can't actually read any of the words when I download it..

PM me your email and I'll send it to you, it reduces the resolution when I upload it on the forum.

.

 

[12rounds]

I installed the gateway bypass today - thanks kaodtech! The truck now allows me to clear all codes in each of the different computer modules - pcm, bcm, etc. After clearing the codes with my newest scanner - Zurich brand from Harbor freight- and running it a bit, nothing came back. I grabbed some fresh cab botanical rodent repellent from tractor supply the other day, so I'm going to close everything up and drop a bag of that stuff in the glove box and hope for the best. Thanks for your help, guys!!!