Plain-English explainer with a connector pinout diagram. Spot a dud heating element in 30 seconds and avoid the most common wiring mistake.
Heated wing mirrors aren't magic — they're a resistance wire sandwiched between the backing plate and the glass. When you press the rear demist button, 12 volts runs through them and the surface warms by 8–12°C above ambient. That's enough to clear morning frost in about 90 seconds.
How to tell if your heater works
- Park the van outside on a cold morning until both mirrors have a thin coat of frost or condensation
- Start the engine and turn on the rear screen demister
- After 60 seconds, run a finger across each mirror — a working heater clears the centre first, edges last
If one side stays frosted and the other clears, the dead side has either a broken heater element or a connector that's worked loose.
The most common wiring mistake
Plugging a heated stick-on glass onto a backing plate that's been cleaned with alcohol-based glass cleaner. The cleaner residue is a non-conductor — wipe with a dry microfibre instead.
Connector pinout cheat sheet
Most Stellantis vans (Citroen / Peugeot / Vauxhall, post-2014) use a 2-pin Molex JST-style connector. Pin 1 is +12V switched through the demist relay. Pin 2 is ground via the door wiring loom.
