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Hitch retrofit - Printable Version

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+--- Thread: Hitch retrofit (/showthread.php?tid=104)

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RE: Hitch retrofit - pacholekck - 03-10-2026

Hi,

I’ve recently retrofitted a towbar in my Volvo XC40. I bought a used TRW module, a used foldable towbar, and a new switch for opening the towbar. Then I used Orbit to code the TRW module.

The mechanism works correctly – I can use the switch to deploy and retract the towbar without any issues.

However, I get a warning in the virtual cockpit saying that the towbar is unlocked. The message appears only while the car is moving and disappears when the car stops. It also doesn’t matter whether the towbar is physically deployed or retracted – the warning still appears.

In the TRW module I have the following error:
B14FB01 – Retractable Towbar Safety Switch – General electrical failure.

Has anyone experienced something similar or knows what could be causing this?

RE: Hitch retrofit - jos - 03-10-2026

Hi,

before i post the long result, try to put your complete post into chatgpt and wonder what you are getting for an answer Smile
I would bet your module is not from an XC40.
Here is my prompt: https://chatgpt.com/share/69b02ec8-c0e4-8005-8ab2-61beea86dc4a

a bit of it...
Quote:TRW Automotive produced several versions of the Volvo retractable towbar module used in vehicles like the Volvo XC40.
Some modules expect different switch logic:
  • Single safety switch
  • Dual redundant switches
If the mechanism and TRW module are from different model years, the module may think the signal is invalid → triggers B14FB01.
This happens frequently when mixing parts from:
  • XC40
  • XC60
  • XC90
  • V60

The car only checks the towbar safety state dynamically while moving.
When stationary, the system assumes it’s safe to deploy/retract, so it suppresses the warning.
This behaviour is normal for Volvo.

I think you need to find out more about your specific module.

Because the warning happens in both deployed and retracted states, the module is probably seeing no safety signal at all, not just the wrong position.
That strongly suggests wiring or switch failure, not coding.


Best Regards JOS

RE: Hitch retrofit - pacholekck - 03-10-2026

Thanks for your answer. I guess my module might be from xc60. What now? Should it be flashed somehow? Can it be done with orbit?

RE: Hitch retrofit - jos - 03-10-2026

I can‘t help with that you need someone experienced, did you read all in the chatgpt link?
I am not sure if you can mix Towbar and Module from different vehicles, possibly this needs to match or you need tricks, which may override safety. Do not give a shit on safety! Wink

Post pictures of the sticker from the components!

Who ever may can help needs to know what you got.

KI asks me:

One quick question that could narrow it down a lot:
  • What are the part numbers of your:
    • TRW module
    • towbar mechanism
Also, if possible:
  • How many pins are in the connector on the towbar motor unit (usually 4 or 6)?
If we assume that the retractable towbar mechanism comes from a Volvo XC60, but it was installed in a Volvo XC40, the issue you are seeing is quite plausible.
The fault code
B14FB01 – Retractable Towbar Safety Switch – General electrical failure
usually means the TRM (Towbar/Trailer Module) is not receiving a valid signal from the safety/lock switch inside the towbar mechanism.
Your symptoms match this perfectly:
  • The towbar deploys and retracts correctly using the switch ✔
  • But while driving, the car shows “towbar unlocked”
  • The message disappears when the vehicle stops
  • It happens regardless of whether the towbar is deployed or retracted
This usually means the lock confirmation signal is missing or incorrect.
Correct Towbar Module (TRM)
For SPA-platform Volvos like the Volvo XC40 (2018–) and Volvo XC60 (2018–), the retractable towbar is controlled by the TRM (Towbar Module).
Common Volvo part numbers include:
  • 31454603
  • 31346521
  • 32369968
  • 32386674
  • 32414268
These modules are used across several SPA cars, including:
  • Volvo XC40
  • Volvo XC60
  • Volvo XC90
  • Volvo S60 / V60 / V90
So in many cases, an XC60 module can technically work in an XC40, as long as the hardware generation and wiring match.
4-pin or 6-pin connection?
The OEM retractable Volvo towbar mechanism normally uses a 6-pin connector between the towbar mechanism and the TRM.
Typical signals in that connector include:
  • Motor power (+ / −)
  • Position sensor
  • Safety/lock switch (locked/unlocked confirmation)
Because of these signals, the retractable system is normally 6-pin, not 4-pin.
A 4-pin connection is more typical for:
  • simpler aftermarket systems
  • or non-retractable towbars.
Most likely causes in your case
If the towbar is from an XC60, one of these is likely happening:
  1. Different safety switch design in the XC60 towbar mechanism
  2. Different pinout between the XC40 wiring and the XC60 towbar
  3. Missing or incorrect lock confirmation signal
  4. Coding expects different hardware
The TRM therefore thinks the towbar is not locked, even though mechanically it is.
✅ What I would check:
  1. The exact part number of the TRM module
  2. The part number of the towbar mechanism
  3. Whether the towbar connector is 6-pin
  4. Pinout of the safety switch line
? If you can provide:
  • the TRM part number
  • the towbar part number
it should be possible to determine quite precisely:
  • whether the towbar is from an XC40 or XC60
  • and why the safety switch fault (B14FB01) appears.


RE: Hitch retrofit - pacholekck - 03-12-2026

Hi, what I was able to check so far are:
hitch number: 32351484
module number: 32386674
Button for hitch opening number: 31399328

My button has 5 pins, but I have only 4 wires connected to it. Is it ok?