LH & EZF Electrical System

Electric power is supplied to the ignition system and LH-Jetronic system from terminal No. 30 of CEB via 3 CEB relays. Turning on the ignition closes ignition relay No. XVI, so that fuel injection and ignition control units receive electric power. If the engine is started, LH fuel control unit puts out negative voltage (ground) to relay No. XXV and relay No. XX.

Both relays close and make connection between terminal No. 3, air mass sensor and LH fuel control unit (power supply) as well as with the fuel pump and fuel injectors. When the ignition is turned off, relays No. XVI and XX open (fuel and ignition off).

Master relay No. XXV, however, is still activated by the LH fuel control unit for an additional 4 seconds, so that power supply is maintained to the hot wire of the air sensor. The free-burning phase for the hot wire (approximately one second) can then be introduced by the LH fuel control unit. The LH fuel control unit switches relay No. XXV off again after completion of the free-burning phase. Terminals No. 30 and 87 of fuel pump relay No. XX must be bridged when fuel pressure has to be checked on a stopped engine.