[ranxerox]

From past forum threads, All it takes is a nail or screw through that backup camera can-bus wire to disable half of the van.
The ones who unplug the harness to the back of the van and reroute it get into trouble too, All it takes is a loose plug or something they forgot to plug back in.

 

[kazuo]

Finding CAN Bus Faults With Multimeter | CAN Bus Diagnostics | Mechanic Mindset

 

[Pisgah Trent]

From past forum threads, All it takes is a nail or screw through that backup camera can-bus wire to disable half of the van.
The ones who unplug the harness to the back of the van and reroute it get into trouble too, All it takes is a loose plug or something they forgot to plug back in.

^^^ THIS ^^^

Okay, I found the problem and it was nothing short of a miracle. One single severed wire in the wire loom at the rear of the van. I guess I hit the right one out of all 40 or so wires there. Repaired it and the van started right up with no error codes.

So I got super lucky because we were about to have it towed to the dealer. I did not put much weight into checking that wire loom, because I assumed that if something had been cut or shorted, you would see other signs of it (blown fuse or faulty device). Can absolutely not believe that Ford designed something such that one single cut wire disables the entire vehicle. Also giving no sign or where the error was coming from. Seems you should get a fault code directing you to that specific wire/device. Instead, you get the entire array of fault codes and a dead vehicle. Thanks Ford.

 

[Scalf77]

Glad to see you found it, looks like you took out the HS1-CAN - line route back to the PCM. The Blue and White twisted pair lines are HS1-CAN, there are two sets one going back to PAM module park assist control module these are spliced back by the tail light with a short stub to the PAM and then back AWD module if available, TCM if available, PCM. Note Depending on the engine the TCM may actually go through a private PCM bus. Looks like you got both the two and from lines.

 

[surly Bill]

Hopefully I and others will remember this the next time someone has a similar problem.
Ranxerox was ON it!

One of the handiest investigation methods: Cause and effect.
When did it work, what was done between then and when it didn't work. Go back and undo or check that thing that was done.

 

[Pisgah Trent]

Glad to see you found it, looks like you took out the HS1-CAN - line route back to the PCM. The Blue and White twisted pair lines are HS1-CAN, there are two sets one going back to PAM module park assist control module these are spliced back by the tail light with a short stub to the PAM and then back AWD module if available, TCM if available, PCM. Note Depending on the engine the TCM may actually go through a private PCM bus. Looks like you got both the two and from lines.

Yes! We were so lucky this time. The scanner was pulling up P0100 and P0101, for PCM and TCM. You were spot on!

 

[pbethel]

Perhaps we could convince the auto makers to have redundant backup systems like aircraft so no single fault can disable the vehicle?

 

[Rolf]

Perhaps we could convince the auto makers to have redundant backup systems like aircraft so no single fault can disable the vehicle?

That would be great but it would cost MEGA Extra $$$$$

 

[as3ffd]

Yeah, would you be willing to pay mucho extra for a problem that never shows up in unmodified vehicles, and rarely in modified vehicles?

 

[surly Bill]

Perhaps we could convince the auto makers to have redundant backup systems like aircraft so no single fault can disable the vehicle?

The older Sprinters had a wiring system that if a rear brake lightbulb was burned out, the van wouldn't run. Not a "safety feature", it was something to do with the CAN bus. They fixed it later on, and wasn't a recall but a TSB. Having learned this on the Sprinter Forum, I always carried a spare bulb. Forums like this one are great for creating a compendium of known issues, especially ones that can be quite traumatic and seemingly complex and expensive until the actual "fix" or prevention is shared by other users.

For example, I give you, The T.U.R.D.

 

[Scalf77]

For the record, there are 4 other CAN Busses on the vehicle. Depending on your config a possible 5th.The MS-CAN bus also goes to the back in the main harness. These wires are violet/orange and gray/orange ( these also can be seen in the picture with damaged wires) You will notice that the wires are a twisted pair, all the communication bus lines will be twisted pairs. HS stands for high speed, while MS is medium speed. The HS2-CAN is Gray/Blue and Green/Orange, HS3-CAN is White/Green and Green Blue, HS4-CAN is Violet/White and Blue/Green

You will notice that all the communication buses go to the gateway module, this also houses the diag connector. The termination for one end of the bus is there, when you see a resister on a module, that is the other end of the bus.

This is off a 2020

 

[Pisgah Trent]

For the record, there are 4 other CAN Busses on the vehicle. Depending on your config a possible 5th.The MS-CAN bus also goes to the back in the main harness. These wires are violet/orange and gray/orange ( these also can be seen in the picture with damaged wires) You will notice that the wires are a twisted pair, all the communication bus lines will be twisted pairs. HS stands for high speed, while MS is medium speed. The HS2-CAN is Gray/Blue and Green/Orange, HS3-CAN is White/Green and Green Blue, HS4-CAN is Violet/White and Blue/Green

Amazing info here! Thanks so much for posting this. So helpful to future use cases.

FWIW, those MS-CAN wires weren't damaged (luckily). Both pairs of white/blue twisted strands were damaged, but the white was the only one fully severed. I wrapped the other damaged ones to prevent any possible short. I haven't done a full test drive yet but everything appears fine. Thanks!

 

[gregoryx]

Any input on how this happened? And any thoughts about how this might have been resolved if that area had been fully enclosed in a roof / wall / cabinet build?

I ask because there have been a couple cases of wiring issues behind build-outs and - in at least one case - there was no resolution other than tearing out the build.

Along with hoping many of us will be able to steer someone else to this thread in a future case, I'm also curious how to help others consider the very real troubles they may be risking behind their build-out. 🤔

 

[Scalf77]

Well one of the first steps, is knowing what is in these bundle of wires, the second one the OP did by running some diagnostics, it did say it could not communicate with the modules. Then of course you need the paper version of the electrical diagrams or a online version. I actually have both. Of course then you actually need to be able to read them, while not difficult it might not be easy for some people. It's not as complex as a lot of schematics I have encountered.

The connectors will be referenced with a "C" like C300, this is under the left hand A-pillar, Here you can see two references to C300 for this bus, you will note that we have two pairs of pins, Before moving to the Park Assist Module you will see "S" for a splice on S913 and S912. Here they splice them together with a stub for the PAM. All stubs off the bus need to be relatively short. This is why we run the bus all the way back to the PAM and then back up terminating at the PCM

The easiest thing you could do to check the integrity of the bus is to just check the termination value. There is a 120 ohm terminating resister between the high and low signals on each end of the bus. So If I were to ohm out across HS1-CAN (high) and HS1-CAN (low) we should read 60 ohm. In the above example the HS1-CAN (low or -) was open, you would not have read 60 ohm across those two line. A good place to make these measurements is at the Gateway module as all the can bus line go there, it also provides the termination for one end of the bus. If you disconnect the connector to the back of the gateway module I would have expected the 120 ohm value would be gone. You can obviously get more involved than that, voltage measurements, a scope , but then you are going above the expected level of the causal van builder.

hope this helps a little more.

 

[Pisgah Trent]

Any input on how this happened? And any thoughts about how this might have been resolved if that area had been fully enclosed in a roof / wall / cabinet build?

In this case, it was my sloppiness with a multi tool blade that nicked the wire bundle. Full accountability there.And I got lucky. In the case of damaging these wires behind a finished wall, I’d say all bets are off. There seems to be no bypass or remedy other than finding and fixing those wires.

Because of this experience, any future work I do to Transits I will create a very explicit path for these wire bundles and make sure they are marked and protected. The problem would lie in a future owner of the van drilling into the wall to install something, and hitting those wires.

 

[16Gemini]

Only problem I see is using a different size wire for your splice. Way back when CAN BUS was new we were told that you could not splice the wiring if you cut it - we proved that theory wrong by doing it out of desperation. I have heard that splicing in a different size wire and/or a poor crimp not making great connection can and will give you hard to find issues. CAN BUS is very finicky about having excellent connections.
Just trying to help with 'old' knowledge and real world experience.