Persistent electrical issues following body damage.

[biggestjosh]

I've been working with insurance and a body repair shop and a dealership for a good while trying to figure this out. Would really love if anyone here might have some insight or recommendations for me. Apologies for the AI-summarized timeline of events, but here's the situation:


Initial Accident:

• Wife sideswiped a cinderblock planter bed while exiting driveway
• Low-speed collision - turned too sharply
• Scraped entire right side of 2021 Ranger Lariat FX4
• Cinder blocks shifted on impact - possibly wedged under truck causing undercarriage damage

Before Body Shop Repair:

• Truck had zero electrical issues
• All systems functioning normally

Body Shop Repair Work:

• Body shop repaired right side damage
• Had to remove aftermarket canopy (installed 2021)
• Had to remove/reinstall tail light assembly
• Removed rear right panel, both door panels, and I believe front right panel and rocker panel
• Found some damage underneath the cab during repairs

A Few Days After Pickup from Body Shop:

• Multiple intermittent electrical issues began:
  • Power to the physical buttons in the center console cuts out
  • All lights on physical buttons in the center console control lights turning on/off
  • All physical buttons in center console stop working
  • Climate vent blower intermittently shutting off
  • Outside temperature gauge not displaying
  • Blind spot monitoring showing errors
  • Collision avoidance fault
  • Airbag fault
  • Turn signals making fast blinking sound (left,right)

Initial Body Shop Response:

• I reported issues to service advisor
• Body shop performed initial scan
• They initially thought it was related to tail light area
• Showed me aftermarket canopy wiring connections (not shrink-wrapped) to tail light
• But there haven't been issues before repair, canopy installed in 2021 (has been fine for 5 years)

Third-Party Diagnostics:

• Body shop sent truck to a diagnostic specialist for advanced scanning
• Found: "suspect the ground and/or a connection issue of some type"
• Mentioned something about "transfer of static electricity"
• Noted damage underneath cab
• Recommended dealership for further diagnosis

Escalation to Ford Dealership:

• Body shop arranged diagnostics at local Ford dealer
• Provided dealership with my symptom list

Dealership Diagnosis:

• Identified problem: Front Control Interface Module (FCIM)
• Theory: damage from accident (cinder blocks wedging under truck) affected module or its connections

FCIM Replacement:

• Dealer replaced Front Control Interface Module
• Truck appeared to work normally
• Brief temporary glitches immediately after replacement:
  • Auto roll up/down window feature didn't work for ~1 minute (only manual hold worked)
  • Parking sensor alert bell sounded different briefly

Post-Repair Period:

• Truck worked normally for a few days
• All systems functioning properly

Current Situation (Today):

• All original electrical issues suddenly returned
• Happened maybe 10 seconds after going over a speed bump
• Same symptoms as before:
  • Center console lights
  • Blower issues
  • Display problems
  • Sensor faults
  • Climate control issues
• NEW symptom: "Restart Now or Key is Needed" message appeared when turning truck off

Key Pattern:

• If the issues were triggered by physical movement (speed bump), this strongly suggests loose connection/ground issue was never actually fixed
• FCIM replacement treated symptom, not root cause
• Underlying wiring harness, connector, or ground connection problem still present
• New module may now be damaged by same issue that damaged original

Sharing the error codes I found with my OBD scanner in the attached image.

Looking for advice: Has anyone experienced similar intermittent electrical issues? Any thoughts on what the issue could be?

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[RangerBill]

• Body shop repaired right side damage
• Had to remove aftermarket canopy (installed 2021)
• Had to remove/reinstall tail light assembly
• Found some damage underneath the cab during repairs

A Few Days After Pickup from Body Shop:

• Multiple intermittent electrical issues began:
  • Center console control lights turning on/off
  • Cabin heater blower intermittently shutting off
  • Outside temperature gauge not displaying
  • Blind spot monitoring showing errors
  • Collision avoidance fault
  • Turn signals making fast blinking sound (intermittent)
  • Climate controls acting erratically

There are a lot of generalizations in your post. Can you be more specific? What center console lights? Which turn signal: left, right, both? What is meant by climate controls acting erratically? What HVAC system do you have - manual, automatic? What trim level is your ranger? What exactly did the body shop remove to do the repair - right front fender, bed, etc. What damage under the cab was repaired? Having these answers may help in tracking down the problem.

 

[biggestjosh]

There are a lot of generalizations in your post. Can you be more specific? What center console lights? Which turn signal: left, right, both? What is meant by climate controls acting erratically? What HVAC system do you have - manual, automatic? What trim level is your ranger? What exactly did the body shop remove to do the repair - right front fender, bed, etc. What damage under the cab was repaired? Having these answers may help in tracking down the problem.

Thanks for the questions, I just edited my post to address. 2021 Lariat FX4 supercrew.

All power gets cut to all physical buttons in the center console (the lights on the buttons go out, and they stop functioning.)

The blower/fan for climate control loses power and cuts out. (Doesn't matter if it's set to automatic or manual)

Turn signals fast blink both left and right.

Alerts pop up on the front display for airbags, parking sensors, blind spots, pre-collission warning. And now when I turn the truck off a display pops up, "Restart Now or Key is Needed" (key fob battery is only a few months old)

 

[RangerBill]

Thanks for the questions, I just edited my post to address. 2021 Lariat FX4 supercrew.

All power gets cut to all physical buttons in the center console (the lights on the buttons go out, and they stop functioning.)

The blower/fan for climate control loses power and cuts out. (Doesn't matter if it's set to automatic or manual)

Turn signals fast blink both left and right.

Alerts pop up on the front display for airbags, parking sensors, blind spots, pre-collission warning. And now when I turn the truck off a display pops up, "Restart Now or Key is Needed" (key fob battery is only a few months old)

Can you scan for any DTC codes and post them?
There is a ground located under the passenger seat (G302) that provides the ground for a couple of the center console switches. I would check that for being tight.

 

[airline tech]

It's on the DCDC Convertor - Circuit - so bad connection on the Power or Ground side, Ground is the most likely - as the Ground Point - G230 is in the RF Fender area.
This is the tie in for all of your faults
If I were to T-Shoot this (I would Start here)

Reseat this connector - DCDC Convertor - under the blower motor

G230 - I do not have an actual pic - the diagrams are not clear; they never are for precise location - But it will be an (8-Gage) Wire - located around the fender
Check this connection for security and or damage

 

[biggestjosh]

This is all helpful, thanks guys. @RangerBill I'm attaching the list error codes I just scanned here.

 

[airline tech]

Ok for all those messages - its pointing to a MS-CAN bus issue, all of the fault codes are on that bus, FCIM - HVAC = FCIM, SODL & SODR (Blind Spot) - Lighting Module = Trailer Module (TRM)

The Fault lies from C237 - going AFT (downstream of this connector)

C237 - Drivers Kick Panel
C422 - LH Frame

Questions

What do you have the Canopy tied into?

Do either of the rear taillamp assemblies have water in them?


I suspect a bad connection - possibly on the RR light assembly being they had it removed; this could take out the can bus as well as any shorted wire in the circuit.

To understand the FCIM - it's always powered, however it takes can bus signal to turn it on (Ignition Switch Position (Run) or ISP-R, the can bus is dropping the signal

Also note the TRM and the Blind Spot Modules are also on the same circuit, so depending on where you tapped in with the canopy - it may be causing the issue (not secured connection) or pinched wire damage during remove and reinstall.

So, check the following connectors for security - Pull - Clean - Reseat (in-Order)

1. Your Canopy - Connections - possibly disconnect to isolate (if issue returns)

2. Both Taillight - Connectors - Check for moisture (under BLIS module and inside light assembly

3. C4483 / C4484 - This is the connection point that the taillamp harness connects to the main truck harness - both sides

4. C422 - LH Frame Rail

5. C237 - Drives side kick panel

My hunch, is that it's in your canopy wire circuit or one of the taillamp assemblies, plus check the wiring for the Trailer Connector as this feeds the TRM

 

[Mighty Little Blue]

Airline Tech and Ranger Bill are like having 2 master techs as your best friends.
Thanks again for all the help you have given to the members here. Karma must really be looking out for you guys.

 

[Cabose-1]

Sounds like my experience with the body shop on my 2020 ranger. Fixed grounds and other issues myself not wanting those monkeys to touchbit again.
I feel bad for people that do not know how to do things on there own and just get taken advantage of. Check the grounds. Airline tech here is a genius with finding diagrams and what to check for.

Good luck

 

[biggestjosh]

What do you have the Canopy tied into?

Do either of the rear taillamp assemblies have water in them?

I'm not sure what the canopy is tied into, I had it installed at a shop. I know there's a 12v connector running off the battery all the way to the canopy to power a USB charger plus a light. I think the connector from the tail light is for the remote lock/unlock on the canopy. This is tapped into the left tail light.

The right tail light does have some moisture in it, I cracked the lens a few years back. I assume they would have had to remove the right tail light to remove the right body panel on the truck bed, so perhaps they didn't reseat it properly and that moisture is causing issue?

 

[RangerBill]

I'm not sure what the canopy is tied into, I had it installed at a shop. I know there's a 12v connector running off the battery all the way to the canopy to power a USB charger plus a light. I think the connector from the tail light is for the remote lock/unlock on the canopy. This is tapped into the left tail light.

The right tail light does have some moisture in it, I cracked the lens a few years back. I assume they would have had to remove the right tail light to remove the right body panel on the truck bed, so perhaps they didn't reseat it properly and that moisture is causing issue?

There have been reports of moisture in the taillights causing issues with the Canbus communications with other modules due to the BLISS module mounted in the taillight getting wet and causing shorts. This may be the reason for your many U DTCs which indicate communication issues. You could unplug the taillight connecters on the taillight that has the water in it and see if you can reset the DTC codes.

 

[airline tech]

If you have moisture in the RR Taillight - That is the issue

Inside the light assembly is the internal wiring for the light assembly plus a connector for the Blind Spot Module (SODR) - Side Obstacle Detection (Right)

The connector is wet and creating a short across the circuits - affecting the MS-CAN bus, to isolate
Depending on if you can clear the codes and all the codes return - then disconnect the RR taillight and clear the codes and if only the RR taillight (BLIS) shows (as its disconnected) - confirms the RR light assembly is shorted out, more so the BLIS module

More Detail:
The internal connector for the SODR (BLIS) module has been exposed to moisture and is wet along with the module itself (this can short the circuit and or the module) as well as the internal wiring for the lights themselves.

I suspect - the tie in - (if they disconnected) the external connector and stored the assembly (as logically they would have stored it - back side down) all the water in the assembly would have drowned the module and connector in a pool of water.
This is why is showed up after the body work (Theory-Only)

To give an understanding of what is happening
The MS-CAN bus wiring runs into connector (C422) and feeds the BLIS modules on Pins 33 & 34
Then after the BLIS modules the MS-CAN bus runs back through connector (C422) on Pins 31 & 32 and then runs to the TRM and then the FCIM (via wiring splices S411 and S412) in the rear harness.
The Can Bus has - 2 Ends (The GWM and the FCIM) - The FCIM is the terminating end of the circuit.

So, everything on the (Circuit Path) from the BLIS modules back up through C422 is being affected and with moisture found in the RR Taillight assembly - points directly at that being the root cause but can still be a connection issue at C422 or C4483/C4484 or either taillight connector or BLIS connector or the wiring splice points where the 2 circuit paths join together.
For me the moisture is the smoking gun here

And for Reference - The Rear Body Harness (Harness # 144045) is the harness aft (downstream) of the C422 connector - this is where the splice points S411 & S412 are located to feed back up through the C422 connector to complete the circuit to the TRM and FCIM modules, specific locations of the splices unknown as the diagrams are not that clear - it's a matter of cut the harness wrap open and find them again this is just for reference, but still a circuit issue possibility

Reason - Moisture can wick up the wires into connectors or splices from another source

I am surprised this has been to various shops and no one understands the circuit and how it operates - you are not the first one to experience issues here for this circuit and once you understand the circuit run - it's clear to see the issue
The throw-off is understanding that the circuit - routes back to the BLIS modules and then back up - is the KEY factor.

 

[biggestjosh]

If you have moisture in the RR Taillight - That is the issue

Inside the light assembly is the internal wiring for the light assembly plus a connector for the Blind Spot Module (SODR) - Side Obstacle Detection (Right)

The connector is wet and creating a short across the circuits - affecting the MS-CAN bus, to isolate
Depending on if you can clear the codes and all the codes return - then disconnect the RR taillight and clear the codes and if only the RR taillight (BLIS) shows (as its disconnected) - confirms the RR light assembly is shorted out, more so the BLIS module

More Detail:
The internal connector for the SODR (BLIS) module has been exposed to moisture and is wet along with the module itself (this can short the circuit and or the module) as well as the internal wiring for the lights themselves.

I suspect - the tie in - (if they disconnected) the external connector and stored the assembly (as logically they would have stored it - back side down) all the water in the assembly would have drowned the module and connector in a pool of water.
This is why is showed up after the body work (Theory-Only)

To give an understanding of what is happening
The MS-CAN bus wiring runs into connector (C422) and feeds the BLIS modules on Pins 33 & 34
Then after the BLIS modules the MS-CAN bus runs back through connector (C422) on Pins 31 & 32 and then runs to the TRM and then the FCIM (via wiring splices S411 and S412) in the rear harness.
The Can Bus has - 2 Ends (The GWM and the FCIM) - The FCIM is the terminating end of the circuit.

So, everything on the (Circuit Path) from the BLIS modules back up through C422 is being affected and with moisture found in the RR Taillight assembly - points directly at that being the root cause but can still be a connection issue at C422 or C4483/C4484 or either taillight connector or BLIS connector or the wiring splice points where the 2 circuit paths join together.
For me the moisture is the smoking gun here

And for Reference - The Rear Body Harness (Harness # 144045) is the harness aft (downstream) of the C422 connector - this is where the splice points S411 & S412 are located to feed back up through the C422 connector to complete the circuit to the TRM and FCIM modules, specific locations of the splices unknown as the diagrams are not that clear - it's a matter of cut the harness wrap open and find them again this is just for reference, but still a circuit issue possibility

Reason - Moisture can wick up the wires into connectors or splices from another source

I am surprised this has been to various shops and no one understands the circuit and how it operates - you are not the first one to experience issues here for this circuit and once you understand the circuit run - it's clear to see the issue
The throw-off is understanding that the circuit - routes back to the BLIS modules and then back up - is the KEY factor.

Thank you for such a thorough write up. Just to confirm, the RR tail light is the one that has moisture, but it's NOT the one with the wire tap for the canopy.

To make sure I'm understanding what you're saying, your hunch is that when my right rear tail light was removed, it was probably set lens side up, which would have caused any moisture that was in it to pool around the BLIS module and its connector. Because the MS-CAN bus routes through the BLIS modules and then loops back forward through C422 to reach the TRM and FCIM, a short at that point would cascade upstream and take out everything on the circuit (which matches all six of my U-codes). Am I understanding that right?

 

[airline tech]

yes

O & P are the feeds coming from C237 (from the GWM)
S414 & S415 provide the split to each taillight
S411 & S412 provide the split to reroute the circuit back through C422
So, everything aft of C422 is being affected the circuit runs down and then back up.

This points to anything on the BLIS feed is taking down the rest of the circuit, this means your canopy tie in or one of the light assemblies, if you have verified moisture in the light assembly that is prime suspect but however the canopy tie in at the LF light is also suspect as both BLIS modules are reporting the error.

So, to isolate remove the LR canopy tie in (first) - if issue remains then it's the RR light assembly

 

[RangerBill]

Thank you for such a thorough write up. Just to confirm, the RR tail light is the one that has moisture, but it's NOT the one with the wire tap for the canopy.

To make sure I'm understanding what you're saying, your hunch is that when my right rear tail light was removed, it was probably set lens side up, which would have caused any moisture that was in it to pool around the BLIS module and its connector. Because the MS-CAN bus routes through the BLIS modules and then loops back forward through C422 to reach the TRM and FCIM, a short at that point would cascade upstream and take out everything on the circuit (which matches all six of my U-codes). Am I understanding that right?

Easy test:
Disconnect the right taillight connectors, reset any DTCs and test to see if they come back with the light still disconnected. You will get DTCs concerning the right Bliss and taillight fault, but see if the other concerns go away.

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