Vauxhall Workshop Service and Repair Manuals

Engine Control Unit, X 18 XE1 and X 20 XEV  

The X 18 XE1 and X 20 XEV engines are equipped with the new Simtec 70 engine management system based on the familiar Simtec 56.6.  

The differences between Simtec 56.6 and the Simtec 70 in the X 18 XE1 and X 20 XEV at a glance:  

	Simtec 56.5	Simtec 70	Simtec 70
		X 18 XE1	X 20 XEV
Engine control unit	Conventional	Hybrid	Hybrid
Camshaft sensor	Inductive sensor	Hall sensor	Hall sensor
Crankshaft pulse pick-up	Hall sensor	Inductive sensor	Inductive sensor
Throttle body with:	Throttle valve potentiometer and idle air controller	Throttle valve adjuster	Throttle valve potentiometer and idle air controller
	with bypass duct	without bypass duct	with bypass duct
Hot film mass air flow meter	External intake air temperature sensor	Integrated intake air temperature sensor	Integrated intake air temperature sensor

2.9.3   Engine Control Unit, X 18 XE1 and X 20 XEV (continued)  

	Simtec 56.5	Simtec 70	Simtec 70
		X 18 XE1	X 20 XEV
Ignition coil	DIS	Ignition coil (4	DIS
	(dual spark ignition coil)	individual ignition coils with integrated spark plug connectors)	(dual spark ignition coil)
Fuel pressure regulator	Pressure regulator attached to fuel distributor pipe	Pressure regulator integrated into fuel tank module	Pressure regulator attached to fuel distributor pipe
Coolant temperature sensor	Engine control unit	Engine control unit, engine cooling module control unit,	Engine control unit, engine cooling module control unit,
Signal sensor for:
		Temperature gauge	Temperature gauge

2.9.3   Engine Control Unit, X 18 XE1 and X 20 XEV (continued)  

The engine control unit in the X 18 XE1 is fastened to the intake module and that in the X 20 XEV is beside the battery.  

Notice: 

For information on the hybrid design of the engine control units, consult section 2.12.  

The Simtec 70 engine control units are mainly distinguished by their final ignition stages.  

In the X 18 XE1, the engine control unit is equipped with 4 final ignition stages.  

In the X 20 XEV, only 2 final ignition stages are used.  

I  4 final ignition stages X 18 XE1  

II  2 final ignition stages X 20 XEV  

15 Ignition ON  

2.9.3   Engine Control Unit, X 18 XE1 and X 20 XEV (continued)  

The two wiring harness connections for the engine and body each have 64 pins.  

The wiring harness plugs are impossible to confuse due to their individual recesses in the control unit (mechanical coding) and on the wiring harness plugs.  

1  Plug connection, engine wiring harness  

2  Plug connection, body wiring harness  

31 Ground (terminal 31)