Electric Heater Not Working? Troubleshooting Tips

Hello,

Okay, so the electric coolant auxiliary heater in my car (Golf 4, 66kw ALH, manufactured in July 2000, 100,000 km) isn't working anymore. It's supposed to provide extra heating after a cold start.

The error memory is empty.
The actuator test with these two outputs for the relay works: I can hear the relay clicking, and based on the interior lighting, I suspect that electrical energy is being converted into heat.

http://kuypers.bei.t-online.de/Bild1.jpg

The bit patterns in 16-2 and 16-3 no longer change when the engine warms up.

It looks like there's a problem with the engine control unit. The rightmost bit = 1 in position 16-2 should actually be = 0.

Best regards, Gerd.

Hello,

Group 16, Field 2 indicates the reason why the auxiliary heating is turned off.

Bit 8: Coolant temperature greater than 70°C or intake air temperature greater than 5°C.
Bit 5: Engine speed below 800 RPM.
Bit 4: Engine start within the last 10 seconds.