Hello everyone,

I own a Focus Mk3 Estate 1.6 TDCi.

About a year ago, the Restraints Control Module (RCM) stopped working, most likely due to a weak/old battery. At the same time, the heated seats also failed. A service workshop confirmed that the RCM had lost power. They installed a bypass power feed to the module, and since then it has been functioning normally. However, the heated seats are still inoperative.

I have checked fuses F34 and F35 – both show 12V with ignition on. Yesterday, while looking for a fuse to connect a dashcam adapter, I found that F85 only supplies ~0.02V with ignition on (0V with ignition off). According to the diagrams, F85 is linked to both the airbag module and the heated seats.

Has anyone experienced a similar issue? Could this point to a BCM fault, and does the module need to be replaced, or should I trace wiring/relays first?

Thanks.

Edit: According to attached chart, F41 is before F85. F41 has 12-14v.

Heated seats.pdf

Fuse F85 is powered as follows:

PFB (Pre Fuse Box) Fuse PF3 (100A) --> EJB (Engine Junction Box) Fuse F41 (20A) --> EJB (Engine Junction Box) Relay R16 --> BCM (Body Control Module) Fuse F85 (7.5A).

I suggest to check Fuses PF3, F41 and Relay R16 first.
 

Inside the BCM the F85 and F86 fuses share the incoming power supply. If F86 does have power and F85 does not have power the problem is caused by an internal BCM fault. If both do not have power there will be a different problem.

@JW1982 I don't have F86. F41 has 12-13v on ignition state. According to the chart(applied at first comment) that I found-R16 is before F41, is it true?

39 minutes ago, alpdbg said:

I don't have F86.

Is your car a European model ?

Does it have a rear wiper ?

@unofix yes, its European model. Yes, I have rear wiper. I don't know if the workshop removed this fuse when creating a bypass to RCM. I checked now-F86 has voltage around 12-14V with ignition on, F85-around 0.03V.

With out knowing what the  workshop might or might not have done it's impossible to guess at the issue.

Fuse holder F85 and F86 share the same internal live supply. Further more  with out fuse F85 your rear wiper would not function.

 

I checked again and there is no F86 and my rear wipe is working fine. I asked them and they didnt remove any fuse. Just created new bypass to power the RCM... I will go next week and I will talk again with them. Thanks.