LH & EZF Electrical System

Electric power is supplied to the ignition system and LH-Jetronic system from terminal 30 of CEB via 3 CEB relays. Turning on the ignition closes ignition relay "XVI", so that fuel injection and ignition control units receive electric power. If the engine is started, LH control unit puts out negative voltage (ground) to relay "XXV" 85 and relay "XX" 85.

Both relays close and make connection between terminal 3, air mass sensor and LH control unit (power supply) as well as with the fuel pump and fuel injectors. When the ignition is turned off, relays "XVI" and "XX" open (fuel and ignition off).

Master relay "XXV", however, is still activated by the LH 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 control unit. The LH control unit switches relay "XXV" off again after completion of the free-burning phase. Terminals 30 and 87 of fuel pump relay "XX" must be bridged when fuel pressure has to be checked on a stopped engine.