Focus Mk2 CC - ECU Reset

[focus-cc]

Hello everyone,

It's been a few months that I have been trying to solve an issue with airbag light turning on a few seconds after ignition.

Forcans shows these errors:
- C1956-20 Steering Angle Sensor Circuit Failure
- B1342-A0 ECU Defective

When I reset DTC using Forscan, and these errors always come back

I contacted a shop specialized in car electronics for 2 services:
- First, a reset of the airbag control module - did not change anything
- Second, bought a spare airbag control module, they loaded the config from my airbag control module to the new one - did not change anything

I replaced the steering angle sensor inside the steering wheel - did not change anything

Looking at the error details, Forscan suggests an ECU reset. My question is - How do I reset the ECU from Forscan?

Thanks!

[Don Ridley]

The ECU is generic for the PCM. Some changes like tire size in a F150 require a PCM parameter reset or module relearn. This is what you may need to do. You should research this before doing anything.

[focus-cc]

Thanks, I am starting to understand, but in this case, ECU must be generic for RCM, because the error appears to be in the RCM - https://imgur.com/a/BEDrtrx

Forscan has a few features for RCM - On-demand Self-test, Module Reboot, and Module Configuration, but nothing solves the issue

I run the all features for PCM just in case, and no change

So I am still with the issue...

[Don Ridley]

***edit corrected B code explanation****

Since you replaced the RCM without success you need to start looking for problems in the wiring and connections. "B" codes are related to problems in the body modules like the RCM. You will need wiring diagrams to see which network is used by the RCM (typically the HS CAN). The problem may be as simple as wires running against something or corroded connectors.

These types of problems stump many auto repair shops and can be very frustrating. But once you isolate the physical components involved you can inspect and rest them. Corrosion is common if you live in a wet/snowy environment where salt is applied to the roads. A tiny crack in wire insulation can turn into a corroded mess.

[focus-cc]

Hi @Don Ridley

I found the wiring diagram, and the RCM is connected to the Mid Speed CAN. Checked the respective resistances and voltages on the OBD plug, and on the RCM plug, and it's all normal. An issue with the CAN BUS broken or shorted would likely not only give errors in the RCM anyway. I can check the sensors one by one but I am hopeless, that's what different DTCs are supposed to indicate, instead of throwing a module error because of a broken sensor.

At this stage, I suspect that both modules are broken or misconfigured, and I am considering having it checked by a dealer...