When the GP light doesn't turn on, it's supposed to indicate a burned out GP, BUT sometimes if you have 2 burned out GP's the system is 'tricked' and thinks everything is normal. You can check the GP's with an ohm meter, but this too can be tricked. Sometimes when the GP's get hot, they expand and the electrical connection is broken, preventing the GP from fully heating. This is usually the case when you try to remove the electrical wire from the GP and the whole thing turns.

If you plug your block heater in for a few hours the car is more likely to start if you have one or two burned out GP's.

Good luck.

Marty

www.benzbonz./biz