Originally Posted by funola

Glow light in dash not indicates one or more burned out glow plug (read your owners manual). Replace #1 and go from there.

Maybe you had the glow plug connector connected when yous measured 1.5 ohms on #1? To proof to yourself why it's important to disconnect the connector is measure the 4 pins on the glow relay, you'll see they are all connected together. That means (if the connector is plugged in) when you take resistance measurements, all you need to 1 good glow plug to get good readings on the rest, i.e. the readings are not to be trusted.