Start-up glowing, function

P15.20-2097-76

B11/4 Coolant temperature sensor

N14/2 Glow output stage

N3/9 CDI control unit

N73 DI control unit

R9 Glow plugs

Key positions:

0 The key can be withdrawn only in position 0

1 The majority of electrical consumers can be switched on

2 Preglowing and driving position

3 Start position

Task

The cylinder specific actuation of the glow plugs (R9), in order to secure a hot surface of the glow plugs (R9) before engine start, on which the fuel/air mixture evaporates in the compression cycle and ignites (start-up glowing).

Function

Startglowing is initiated when the ignition key is turned on into position 3.

The glow output stage (N14/2) is supplied with a signal by the CDI control unit (N3/9) that the engine is being started; the glow plugs (R9) continue to be supplied with voltage. Afterglowing is activated when the starter release speed is reached.

 If the ignition key is not turned on in position 3 after the preglow indicator lamp has gone out, glowing is continued for a approx. 25 seconds, irrespective of the coolant temperature (start readiness glowing).

If a starting procedure is interrupted and restarted again after this, the glow output stage (N14/2) prevents a second glowing procedure in order to avoid a thermal overload of the already hot glow plugs (R9) (repetitive starting-detection).