The glow plugs should receive power for only a brief time, duration
depends upon the temperature of the engine block. For sure not beyond 30
seconds in a moderate climate. Suggest you check the voltage to the GPs
after the engine has been started and is running, it should soon be zero.
Beru offers a retrofit relay that extends the interval to reduce smoke
emissions but, to give you a perspective, its total glow time is about
All that said, I hope you were installing Beru or Bosch GPs.