Limp Mode and RCM Codes After Interior Removal

[XanRules]

Hey y'all, I am absolutely stumped here.

Over the weekend, I stripped the interior out of my car - I removed the front and rear seats as well as much of the interior trim and the carpet in order to put down sound deadening and soundproofing. Basically everything except for the dashboard, steering wheel, and headliner came out. I also disconnected the APIM and the module below it so I could more cleanly run the wires for a backup camera I installed a few months ago. The battery was disconnected for the majority of the weekend, save for a few times when I’d re-connect it to roll a window up or down or open the trunk.

The car is mostly reassembled minus some of the plastic trim (lower B pillar, kick panels).

Since reassembling the car, it’s been in limp mode. I’ve got the wrench icon telling me “Engine Fault - Service Now,” as well as the air bag and traction control lights on the dash. Hill Assist and 911 Assist are both not working. I have confirmed that - as far as I can see, visually - everything was reconnected as far as both the seats and the seatbelts go. No water was used in the car at any point and no connections got wet. My battery terminal connections are tight, though I have not checked the voltage of the battery. No water got into the car on any of the sensors, and while I did clean the carpet while it was out, it was left out to dry in direct sunlight from Saturday morning until last night.

FORScan is giving me the following codes:
PCM Code U210B - Lost Communication Between Fuel Pump Control Module ‘A’ and Restraints Control Module
APIM Code U0151 - Lost Communication with Restraints Control Module
APIM Code 0452 - Invalid Data Received from Restraints Control Module
OCS Code U0151 - Lost Communication with Restraints Control Module
ABS Code U0151 - Lost Communication with Restraints Control Module
Restraint Control Module - Error, Unable to Read DTC
IPC Code U0151 - Lost Communication with Restraints Control Module

My guesses are:

1. The car was turned on while all the airbags were unplugged (seats removed etc) and it remembers there being a code of some sort and I need to clear it. Clearing the codes in FORScan does not remove them permanently, they come back when the car is turned off and back on again, but there may be something else going on there.
2. I somehow bumped or disconnected the RCM when removing and reinstalling the center console and/or the carpet, since the carpet passes right under the RCM.
3. There is something pressure sensitive somewhere that does not like having sound deadening foam near it (no modules are covered, only the floor itself is), or some sort of sensor connected to the B pillars where the airbag and seatbelt tensioners are that throws a code if the trim is removed.

1 or 2 seem most likely to me, but I’d love some expert input before I remove the center console again.

Thanks in advance.

 

[rallytaff]

Some people won't leave things alone and then wonder why they don't work!

 

[Switchback]

Seems like the RCM isn't powering on or isn't connecting properly. It /could/ have failed, but that seems a bit of a longshot. I hate to say this but you'll have to pull the center console out and I'd inspect the connection to the RCM. Check the pins/plug on the connector/module side. I'm assuming the RCM is similar to one in a base fiesta so worst case you could go junkyard diving if you find its properly broken. Car systems are usually programmed to assume the worst if the safety system is inactive/removed.

Some people won't leave things alone and then wonder why they don't work!

Some people like to make irrelevant comments and then wonder why people don't like them very much.

 

[Grsemky]

Some people like to make irrelevant comments and then wonder why people don't like them very much.

Aww leave the curmudgeon alone, he cant help it lol

 

[XanRules]

Seems like the RCM isn't powering on or isn't connecting properly. It /could/ have failed, but that seems a bit of a longshot. I hate to say this but you'll have to pull the center console out and I'd inspect the connection to the RCM. Check the pins/plug on the connector/module side. I'm assuming the RCM is similar to one in a base fiesta so worst case you could go junkyard diving if you find its properly broken. Car systems are usually programmed to assume the worst if the safety system is inactive/removed.


Some people like to make irrelevant comments and then wonder why people don't like them very much.

Yeah, I am strongly leaning towards option two. It's in the same place in all cars, and as you can see in this picture, the carpet passes under the RCM cables themselves. I had to cut it the carpet to get it out since it is a single piece that otherwise requires removal of the dashboard and all components of the center console to get out, and I cut it just off to the side. I know for a fact that I did not cut any cables, so I imagine I just bumped one of the connectors when I was taking it out or putting it back in.



Classic Ford, of course, putting an incredibly sensitive piece of safety equipment between two parts of the car that are frequently interacted with by the driver, and also running the carpet underneath it. Every time I work on this car I have another moment of "why the hell would you design it like that?"

 

[Nitelife]

Another vote for inspecting the RCM and ensuring that it's bolted securely and all connections are tight. Battery voltage could have dropped since you left it unplugged, but were also using it roll windows/open hatch. I feel like I read if the voltage drops below 10V that can cause issues with the RCM.

AI suggested Key Diagnostic Steps

1. Check RCM Power and Ground: Inspect the RCM wiring harness under the center console/dash for damage, and ensure the module is securely bolted to the body for proper grounding.
2. Battery Voltage Check: Test the battery and alternator, as low voltage frequently triggers widespread U-codes.

 

[XanRules]

Another vote for inspecting the RCM and ensuring that it's bolted securely and all connections are tight. Battery voltage could have dropped since you left it unplugged, but were also using it roll windows/open hatch. I feel like I read if the voltage drops below 10V that can cause issues with the RCM.

AI suggested Key Diagnostic Steps

1. Check RCM Power and Ground: Inspect the RCM wiring harness under the center console/dash for damage, and ensure the module is securely bolted to the body for proper grounding.
2. Battery Voltage Check: Test the battery and alternator, as low voltage frequently triggers widespread U-codes.

Thank you so much, I was reading that low voltage and/or grounds not being secure would cause issues but none that singled out the RCM.

I'll take the center console out tonight and check the RCM connections. Mercifully it's only four 7mm bolts and a few clips, unlike everything else in this car. While I do that, I will disconnect the battery and put it on a trickle charger.

Also god, FORScan is worth every penny, I cannot imagine how much I would have spent in diagnostics trying to figure this out without it.

 

[XanRules]

Well there's your problem.

 

[Sam4]

partial eject/not clamped? (neuron stimulation appreciated)

 

[XanRules]

partial eject/not clamped? (neuron stimulation appreciated)

Correct. I clearly bumped the little grey latch at some point during the removal/reinstallation of the carpet and center console and the RCM had come partially unplugged. Clicked it back into place and everything fired right up, no issues, FORScan not showing any codes.

In looking at the photo I could have maybe stood to wipe the coffee stains off the top of the RCM, but that's what Ford gets for putting it under the cupholders.

 

[Switchback]

Sometimes I wonder if car vendors do that on purpose. "Lets put the most critical module for a vehicle right in the center console where it may get soaked in various fluids (bodily or otherwise)"

Glad it was something simple like that!

 

[XanRules]

Me too. There really are a lot of baffling design decisions in this car - the cabin air filter comes to mind. The carpet is another baffling one. It's a single piece of foam/carpeting which was put in before anything else in the interior, which means that to get it out in one piece you'd have to take the dashboard out. You can see that there's a little spot under the RCM where the carpet connects, and you can see in that photo where I cut it. There is another such connection like that behind the dashboard, if you reach all the way back from where the cabin air filter housing is you'll be able to feel it. Totally nuts.

That said, I'm really glad I'm at a point in my life where I know enough about cars that I can go "okay, it's probably this simple thing because I know I was careful and have some idea what I'm doing" instead of freaking out - it's taken twenty years of trial and error and several catastrophic events to get to this point. You gotta make a lot of mistakes to learn from your mistakes. And, of course, I got the free trial of FORScan at just the right time and will be paying for the full license going forward since being able to read those codes saved me god-knows-how-much time and money.

Unfortunately, I am going to have to take a lot of this stuff BACK out AGAIN to run wires for the subwoofer and the amplifier under the carpet and stash the amp under the driver's seat, but at least now I know how to do it and what not to bump into when I do.

Anyway, those are my thoughts on the subject for the day.

 

[Switchback]

Me too. There really are a lot of baffling design decisions in this car - the cabin air filter comes to mind. The carpet is another baffling one. It's a single piece of foam/carpeting which was put in before anything else in the interior, which means that to get it out in one piece you'd have to take the dashboard out. You can see that there's a little spot under the RCM where the carpet connects, and you can see in that photo where I cut it. There is another such connection like that behind the dashboard, if you reach all the way back from where the cabin air filter housing is you'll be able to feel it. Totally nuts.

That said, I'm really glad I'm at a point in my life where I know enough about cars that I can go "okay, it's probably this simple thing because I know I was careful and have some idea what I'm doing" instead of freaking out - it's taken twenty years of trial and error and several catastrophic events to get to this point. You gotta make a lot of mistakes to learn from your mistakes. And, of course, I got the free trial of FORScan at just the right time and will be paying for the full license going forward since being able to read those codes saved me god-knows-how-much time and money.

Unfortunately, I am going to have to take a lot of this stuff BACK out AGAIN to run wires for the subwoofer and the amplifier under the carpet and stash the amp under the driver's seat, but at least now I know how to do it and what not to bump into when I do.

Anyway, those are my thoughts on the subject for the day.

The Cabin Air Filter is relatively easy to do once you have the right tools, I can do it in 15 minutes with a thumb-screw ratchet and compressing the filter a bit. The official Ford way of doing it is stupid as sin and requires the dashboard removal.

Just as a heads up regarding Forscan, if you use the 2 month trial you can either just request new 2 month trials or just modify your computers date to a time when that license was valid and never need to pay.

 

[XanRules]

Oh yeah, it's not terrible if you have a thumb-screw ratchet, I bought one just to do the cabin air filter, but it's still a very stupid design. On the Japanese cars I've owned, it's just "drop the glovebox and slide it out." On the RHD Fiesta ST it's three easily-accessible screws iirc. The amount of contorting a big idiot like me needs to do to get that thumb-screw ratchet into the right place - plus the need to squash the filter - is very stupid.

And yeah, one annoying thing re FORScan is that there seem to be some "advanced" features like flashing an APIM Firmware Update (not the CyanLabs Software Update) that are locked unless you have the actual "paid" version. I am certainly happy to pay them given how useful I've found the software (I also paid for Reaper and WinRAR, I'm a sucker like that) but I also don't see a way to pay them, so, whatever, if I ever need to do that I'll figure it out then.

 

[Switchback]

Oh yeah, it's not terrible if you have a thumb-screw ratchet, I bought one just to do the cabin air filter, but it's still a very stupid design. On the Japanese cars I've owned, it's just "drop the glovebox and slide it out." On the RHD Fiesta ST it's three easily-accessible screws iirc. The amount of contorting a big idiot like me needs to do to get that thumb-screw ratchet into the right place - plus the need to squash the filter - is very stupid.

And yeah, one annoying thing re FORScan is that there seem to be some "advanced" features like flashing an APIM Firmware Update (not the CyanLabs Software Update) that are locked unless you have the actual "paid" version. I am certainly happy to pay them given how useful I've found the software (I also paid for Reaper and WinRAR, I'm a sucker like that) but I also don't see a way to pay them, so, whatever, if I ever need to do that I'll figure it out then.

That's fair regarding the air filter, I did my Tesla Model 3 filter and it was super easy. There's got to be a better way! (Insert informercial here)

I think it's due to the fact the developer is in Russia, and with the whole world events thing going on it might be impossible to transfer funds to a russian without a lot of three letter agencies coming down like a bag of bricks. Interesting about APIM firmware, must be like BIOS/Bootloader level stuff.