Hello everyone. My name is Martin and I'm from Holland. I drive a black Ford Puma ST-Line with the 125PS mhev engine.

I get fault messages on the display when my dashcam parking battery takes power when it is connected to the 12V outlet. I have programmed the timeout of the 12V outlet to 1 second with Forscan so that it does not take power when the contact is off. The plug has a switch with a light so that I can see when it is on or off. This 12V battery takes a maximum of 6.5 amps, depending on the ambient temperature, in increasing steps. The instruction manual of the Puma states that devices up to a maximum of 15 amps can be connected to the 12V outlet. Some days after connecting the dashcam battery for the first time, fault messages appeared while driving such as BLIS, adaptive cruise control, parking aid etc. being deactivated, together with the orange wrench light (warning light drivetrain) going on and the message ”see owner’s manual” in the diplay. When this occurred, I then stopped the car and read the instruction manual, and it says about the warning light drivetrain: not to accelerate or brake fast and get the car repaired immediately. About 5 minutes later I start the car again to drive home and the warning light drivetrain is no longer on, also all auxiliary systems such as BLIS, adaptive cruise control etc. work normal again.

At home I read the errors with forscan and it starts with the first fault: ===PCM DTC P1935:00-68=== Code: P1935 - Brake Switch/Sensor Signal followed by information about it. Next message is ===PCM DTC U0121:00-28=== Code: U0121 - Lost Communication With Anti-Lock Brake System (ABS) Control Module 'A'. followed by many more fault messages.

A week before this, the car was at the dealer for an oilchange. I contacted them and explained the situation and they called me back later after consulting their technician. They told me that they did not have an idea why the faults appeared and disappeared again and wanted to have the car in to diagnose the problem. I decided not to bring it in because faults disappeared and wanted to find out myself if faults where appearing again while the dashcam parking battery was not connected. After doing that no fault messages returned. Last week I reconnected the dashcam parking battery again and within a couple of days ,while driving, the same type of error messages appeared on the display. Reading the faults in Forscan and they are practically the same again.

Every now and then I also get the message "preserve battery" when I get into the car. And auto start stop is not active at first start (warning light auto start/stop also indicates this correctly) and it starts working fine when you drive for a few minutes. Both these behaviors only since it got colder outside. Otherwise, no problems, car always starts, and hybrid system is always active. I do not use the Ford app.

What can cause these error messages? I hope to get more information for this before I book it in for diagnose at the local Ford dealer. I do have 4 year warranty but 12V battery and hybrid battery are only covered for 2 years which is now over.

Remove the camera, which I doubt very highly is causing anything and take into Ford.

Give them the codes you have read, that will help you.

Is main 12v battery at a good level of charge?

2 hours ago, DaveT70 said:

Remove the camera, which I doubt very highly is causing anything and take into Ford.

Give them the codes you have read, that will help you.

Is main 12v battery at a good level of charge?

Hello DaveT70,

Thanks for your response.

I drove 50 minutes today, twice. 40 minutes after the last drive I measured 12.33V on the battery terminals with a multimeter when the engine was off. When the engine was on I measured 14.92V. According to the Varta-automotive website 12.33V is in the status "Abnormal vehicle status, sulphate risk". Maybe I have a 12V battery that is likely to fail soon? Considering that the 12V battery had a bad start because it was probably not charged for a while when it left the factory, could it be at the end of its life so quickly? Or is it possible that the electrical system is not up to its task to maintain the 12V battery, so that its life is shortened? That would mean that if I install a new battery I will have the same problems in two or three years. Or maybe earlier because I bought the car in August 2024 and I don't know what problems the previous owner had with it.