FIAT 500 – BATTERY DRAIN

On board electronics in cars are wonderful, when they work ! Most modern vehicles now come with an array of technology enabling Bluetooth communication and infotainment options. This charming little re incarnation of the iconic Fiat 500 takes classic design and brigs modern technology together, a great concept however not without Italian electronic reliability problems.

The customer had brought their FIAT 500 into our workshop to diagnose the cause of the flat battery when the vehicle is left for a  few days.
First we checked battery – came back ok. Code scan showed lots of fault codes mainly battery voltage related, cleared the codes one returned U173387 CTM (TELEMATICS). We put an ammeter in series and it showed a drain of between 50 – 200 milli-amps. Systematically disconnecting fuses we found the drain was from the DLC which fed all of the cars control units. We suspected one of the control units was staying ‘awake’ and running the battery flat.
Using the same process as with the fuses we disconnected the control units until the drain disappeared. Starting with the telematics module as we had a fault code relating to this. Luckily it was quite easy to access, and the drain reduced to 3 milliamps when unplugged. The customer wasn’t fussed if the hands free worked so we left disconnected.

As usual we carried out our complimentary valet and presented the car back to a very happy customer. 🙂