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Stan
Stan, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3526
Experience:  Technical support engineer
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I have just fitted a new auxiliary belt to my 220 cdi 2002

Resolved Question:

I have just fitted a new auxiliary belt to my 220 cdi 2002 and when started the big red battery warning light is on the dash. It was working ok until the belt brook and I have fitted a new one.
Battery is charging ok.
Can this be turned off
By the way the red light cam on when the belt brook as you would expect
Submitted: 2 years ago.
Category: Mercedes
Expert:  Stan replied 2 years ago.
Stan :

Hello,
Replacing the belt should have made the alternator work, without the battery warning message. There is no reset. Possibly the alternator's wiring was damaged by the broken belt, or the alternator's regulator has failed

Stan :

Best regards,
Stan

Customer:

Hi Stan

Customer:

Hello Stan checked the wiring and charging all OK what do you think

Stan :

The regulator seems to have failed. Does the message disappear if you rev the engine to 2-3000 rpm?

Customer:

No and the regulator seems OK . have check output on tick over and at 2000 rpm and is being controlled OK at 14.75 volts. What do you think

Customer:

Just check to see if it would go off as you sujested and tryed it at all sorts of reves up to 4000 rpm still no luck.

Customer:

are there any voltage messurments l can talk for you to make an asesment

Stan :

I would need the VIN to determine the alternator/regulator installed on your car.

Customer:

Hello the vin number is *****

Stan :

When alternator is not charging - there must ground at the pin 1 of the 2-pin plug on the alternator. When charginng- there should be positive.

Stan :

This signal is used to activate the warning message in the cluster.

Stan :

I recommend to have the faults checked with Star Diagnosis computer as well, because the charging warning is triggered as a computerized signal from SAM to instrument cluster.

Customer:

I do think it is strange that it was ok up to the point of the belt breaking when it obviously came on so you would expect when the new belt was fitted it would go out not require a test program on it. I have not disconnected the battery yet do you think that may switch it off

Stan :

Disconnecting the battery is worth a try, since SAM sends a CAN signal to cluster. It might reset the SAM. Otherwise, the alternator works in the classic way.

Stan :

terminal 61 operation check would tell if regulator works as it should.

Customer:

I will try and report back

Stan :

Will be glad to hear from you whenever it's most convenient for you

Customer:

Stan disconnected the battery and reconnected light went straight out and all seems to be working OK.

Stan and other Mercedes Specialists are ready to help you