Test alternator charging current - AR15.40-P-5011RKB

ENGINE 157, 278 in MODEL 231 

Connection scheme 

Fig 1: Testing Alternator Charging Current

Courtesy of MERCEDES-BENZ USA

	Check
1	Check poly-V belt tension
2	Check poly-V belt for wear
	Check visible area of poly-V belt for wear		AP13.22-P-1352EW
3	Check electrical lines to on-board electrical system battery (G1), alternator (G2), starter (M1) and on the ground point for the battery (W10) in the engine compartment for tight seating and check for a perfect condition
4	Remove lower engine compartment paneling		AR61.20-P-1105RK
5	Check ground strap between engine and body for tight seating and proper condition
6	Connect volt amp(s) tester (079) with current clamp (065) according to connection diagram
	Risk of accident  from vehicle starting off by itself when engine running. Risk of injury  (bruises and burns) resulting from working on the engine while it is being started or when it is running.	Secure vehicle to prevent it from starting off by itself. Wear closed and snug-fitting work clothes. Do not touch hot or rotating parts.	AS00.00-Z-0005-01A
7	Start engine
8	Check charging current at high engine rpms; apply load to on-board electrical system battery (G1) for this step using volt-amp(s) tester (079)	Change the load resistance until the maximum charging current is reached. The regulation voltage must not drop below 12.7 V.
		Charging current for alternator Check charging current under specified value, check alternator diodes (G2): ↓	*BE15.40-P-1001-01L
		Test alternator diodes In the case of defective diode, replace alternator (G2): ↓	AR15.40-P-9301-02RKB
		Remove/install alternator	AR15.40-P-5032RKB
9	Turn off engine
10	Disconnect volt amp(s) tester (079) with current clamp (065)

CHECK VALUES FOR ALTERNATOR

Number	Designation			Engine 157 in model 166, 212, 218, 231, 292	Engine 278 in model 231
BE15.40-P-1001-01L	Charging current for alternator	max.	A	180	180
		min.	A	115	140
		Engine speed	1/min	2000	2000
		Gear ratio	i=	2, 93	2, 93