Engine malfunction
Q
My trusty 20-year-old Citroën C15 van failed it’s last MOT due to terminal bulkhead corrosion around the master cylinder and, needing a quick replacement, I found a Ford C-MAX diesel, which was a lot cheaper than the equivalent Transit Connect. Not really what I wanted as not a van and a little too wide for one place I go to, but needs must, etc. The van use is private, not business. Anyway, very nice vehicle to drive, it’s a 2010 vehicle (2003-10 model) with the later 1.8 Duratorq diesel engine – one with a lower belt rather than a chain – 78,000 miles. No issues apart from at random ‘engine malfunction’ comes on the information display, on start up or during the course of a journey (and sometimes goes away as well).
Code reader identifies the fault as 0504 Brake light switch, although the brake lights work OK with the fault. I got my trusted local garage to confirm and they replaced the brake light switch, checked fuses, wiring, etc., yet problem remained.
They do have access to an independent auto electrician, but he’s incredibly busy, and they usually book him for a day at a time to sort several vehicles to make it work and cost efficient for all. So waiting for a date. I’m using the car sparingly, as I have other vehicles but no van. However, interrogating the web revealed a similar issue with several Fords of the same era although different codes were produced, and the common thread was that the two ‘strip contacts’ at the back of the instrument cluster wear over time, particularly as the solder doesn’t have any lead in it and so stray electrical issues can result.
Apparently, removing the cluster and resoldering the strip properly seems to solve the problems.
Do you think this may be my problem too?
Kevin Williams
A
The code P0504 indicates Brake pedal position (BPP) switch A/B – correlation, which is normally an electrical problem, the source of which can vary. One reason for this can be that the ECM has detected that the brake pedal and the throttle pedal are being used at the same time, or that the ECM perceives that they are being used at the same time.
As the brake light switch has been replaced, then this can hopefully be discounted as the source of the problem, which does leave an electronic connection as the source of the fault.
The circuit for the brake pedal position switch (green/white wire) goes through the fusebox relay plate, then onto to terminal G4 on the engine control module (ECM). I would as a first step remove and check the connections on both the fusebox and the ECM, ensuring that light corrosion is not present.
Once this has been checked, then it would be worth carrying out the repair/resolder to the dash panel to eliminate this as a source of the problem. The dash panel on these vehicles can suffer from quite a few different problems due to the failure of the solder.