Will fitting an aftermarket stereo in our Citroën C3 be the cause of its recent electrical faults?

Your motoring problems solved

Car Clinic: Stereo

Q. I recently had a new stereo installed in my daughter’s 2003 Citroën C3. The fitter wired the unit to the cigarette lighter socket rather than the ignition feed, and ever since we’ve experienced intermittent electrical faults ranging from central-locking malfunction to the stereo losing its station presets. I’ve seen the words “Econ mode” flashing on the dashboard at times. Is this a clue to the nature of the faults?
RW, Winchester

A. Your problems are a result of the increasingly smart technology being built into cars. This is all very well when the parts are communicating with one another as intended, but if one is wrongly wired it can throw the entire system into confusion.

A factory-fitted radio wired into the ignition feed is able to talk to the car’s electronic control units (ECUs). But when your installer chose the Heath Robinson option of routing the system via the cigarette-lighter socket, it confused the ECUs that manage the car’s complex electronics.

“Econ mode” is indeed a clue to what’s happening. It is designed to prevent a flat battery by ensuring that if the engine is off (even if the ignition is still on), the ECUs, lights and other electrics will switch off after a short while. The exact amount of time depends on the model of car, the battery charge level and the devices left switched on.

Because the factory-fitted stereo can communicate with the car’s computer to partially override Econ mode, you can play music for about 30 minutes when the engine is off. But this function will not work with an incorrectly wired or aftermarket stereo, so Econ mode will cut the power shortly after the engine has stopped. (Switching the ignition off and on again won’t deactivate Econ mode; the engine has to run for a short while for that.)

Go back to the company and ask it to fit the stereo properly. Do not let it attempt to bypass the Econ mode, as that could damage the ECUs and other electrics, necessitating some costly repairs.
Sunday Times Driving car clinic expert: Dave Pollard

Dave Pollard has written several Haynes manuals and has tested just about every car-related accessory – read more from Dave here.

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