Citroen C4 flashing screen

I would always suspect the battery voltage. If possible, put an oscilloscope on the supply voltage.

I hope it helps you.

I’ll have Picoscope 2204a in 3 days. Can u tell me where should I check this voltages? And why I should use an oscilloscope instead of multimeter?

This may help too: http://c4owners.org/plugins/forum/forum_viewtopic.php?199473

Amugus said:

I’ll have Picoscope 2204a in 3 days. Can u tell me where should I check this voltages? And why I should use an oscilloscope instead of multimeter?

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Connect it across the power supply close to the display.

With a flickering display the supply voltage could be dipping and recovering very quickly, which would be too fast for a multimeter to spot.

I doubt you need oscilloscope for this repair. More likely you just need to open it and check the connection for the screen.

Using a scope on the external supply will just be a waist of time unless the entire unit is cutting on and off and not just suffering a flickering display. These are designed to handle a pretty wide range for input voltage since its automotive and then it would get better regulation inside. IMO you'd most likely get some fault codes if it was anything power related as well (external or internal).

The link to the Citroen C4 forum had someone who had fixed the problem by changing the battery.

Voltage-related problems often don't bring up the fault codes that you might expect because voltages can change quickly.