Pre/post-heating control

The pre/post-heating function is controlled by the ECU.

The ECU controls the glow plug relay box.

1) Ignition on - Preheating

Preheating consists of two phases:

a) Variable preheating

It depends on the coolant temperature, the battery voltage and the altitude (internal ECU sensor) when the ignition is switched on (preheat warning light on).

Upper preheating limit (battery voltage below 9.3 volts and altitude above 2,000 m).

Lower preheating limit (battery voltage above 10.5 volts and altitude below 350 m).

b) Fixed preheating

After the preheat warning light goes out (variable preheating), the glow plugs remain powered for 8 seconds before starting.

2) Starting

While the starter is engaged, all four glow plugs remain continuously powered.

3) Engine running - Post-heating

Post-heating consists of two phases:

a) Fixed post-heating

After starting, the glow plugs are powered simultaneously for 10 seconds.

b) Variable post-heating

Variable post-heating starts at the end of fixed post-heating. The power-on time of the four glow plugs (continuous) depends on:

• coolant temperature,
• engine speed,
• load (load potentiometer on the pump lever).