1. Single rear foglamp is correct

2. Bulb failure module is very sensitive. The behaviour of the warning lamp helps find where the problem is;

If it is an ignition switched circuit giving the problem (brake lights, reversing lights, indicators) then the lamp comes on when you first try to use that light and stays on until the ignition is switched off.

If it is a circuit controlled by the main lighting switch (side/tail lights, number plate, headlights) then the lamp comes on when you switch on the faulty circuit and goes out when you switch it off again.

Check all the bulbs are the correct wattage (tail lights are 10W not the more usual 5W) and there is no corrosion in the bulb holders.

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Mick J
'08 Chrysler 300CRD (MB OM 642 engine)
'95 E220 estate
'89 230TE (R.I.P.)