Test scope	Test connection			Test condition	Nominal value	Possible cause/Remedy
1.0		Preglow indicator lamp (A1e16)	1 (1.1)	N14	3 (1.3)	Unplug preglow time-limit relay module (N14) Ignition: ON	Preglow indicator lamp (A1e16) lights	Light bulb, Wiring, 1.1
1.1			N14 3 (1.3)		N3/7 48	Ignition: OFF Unplug preglow time-limit relay module (N14)	< 1	Wiring.
2.0		Preglow time-limit relay module (N14) Voltage supply	4 (1.4)	N14	1 (1.1)	Unplug preglow time-limit relay module (N14) Ignition: ON	11 - 14 V	Fuse, Wiring, Ground, component compartment - left (W16/3), 2.1
2.1		Circuit 30			N14 Cir. 30	Unplug preglow time-limit relay module (N14). Ignition: OFF	11 - 14 V	Wiring, 2.2
2.2		Circuit 15			N14 1 (1.1)	Unplug preglow time-limit relay module (N14). Ignition: ON	11 - 14 V	Fuse, Wiring, 2.3
2.3		Ground (output ground - component compartment - left) (W16/3)			N14 4 (1.4)	Unplug preglow time-limit relay module (N14). Ignition: OFF	< 1	Wiring.
3.0		Glow plugs			N14 1 (2.1) 2 (2.2) 3 (2.3) 4 (2.4) 5 (2.5) 6 (2.6)	Measure with DC current pickup. Remove windshield washer fluid container, remove cable cover and loosen cable ties, pull back protective sleeve. Turn ignition key for each measurement again to position 2.	8 - 15 A 1)	Glow plugs (Figure 2), Wiring.
4.0		ECT sensor (B11/8)	4 (1.4)	N14	6 (1.6)	Ignition: OFF Unplug preglow time-limit relay module (N14).	oC 20 2500 30 1700 40 1170 50 830 60 600 70 435 80 325 90 245 ± 5%	Engine coolant temperature sensor (B11/8, Figure 1), Wiring, 4.1
4.1		Engine coolant temperature sensor (B11/8)		B11/8	2	Ignition: OFF Unplug connector on engine coolant temperature sensor (B11/8).	Nominal value see 4.0	Engine coolant temperature sensor (B11/8) (Figure 1)

1) After 10 - 20 seconds the nominal value is obtained for a brief moment.