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cappytanjack

The Sam Controls The Alternator Output?

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The original alternator on my 2005 cdi with 74K died a quick death a few weeks back with less than the required 12+ volt output. While driving the car the battery light came on, then the multiple amber light flashes from the ESP plus two other amber lights, then no turn signal lights would function and finally the 3 bars of death just as I was turning in the driveway. The battery voltage was dropping to an all time low of 9.6 volts. The car then refused to shift out of 1st gear and I drove it slowly in first gear into the garage. I purchased a new Bosch alternator from Rock Auto ($145 USD) and it shipped from the UK. Once installed the alternator's ouput would go beyond 17 volts which had me believing the voltage regulator (rectifier) was bad in my new alternator. This was a first for me as I have never had issues with new alternators previously. The rebuild shop in Belleville insists the alternator and regulator are within specifications with a maximum voltage output of 14.6 volts. One technician claims the smart ECU (SAM) is responsible for sending the alternator a signal to produce maximum voltage and it is the ECU (SAM) that is to blame. Has anyone else experienced this problem after an alternator replacement and if so what was the fix? This same technician claims that NAPA can send out the ECU (SAM) for a check-up to see if it is functioning properly. Has anyone tried this service? Thanks for your help.cappytanjack

Edited by cappytanjack

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Posted (edited) · Report post

[

Yikes doesnt sound good.

What I would do is:

[*] Remove the SAM

[*] Check all the contacts to see is there's any burning or corrosion, also check the wires that connect to the SAM

[*] Also check the unit for moisture

My smarts seems to run at around 13.4-13.7V when running. Also bring your battery into Canadian Tire they'll test it for free, I know sometimes when a battery is failing it will bring the voltage up to try and charge the battery.

FYI When my alternator died it also killed my battery.

Edited by smart142

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Did you charge the battery before installing the new alternator?Are the connections at the battery and alternator clean and tight?A fully discharged battery will draw maximum output from the alternator.Bad connections will cause problems with regulation as well.As far as I know the SAM has nothing to do with controlling the output of the alternator, it all done within the alternator.You may need a new battery, old battery's don't like being discharged fully, the plates can warp or the cells sulphate.I would clean and re tighten all connections first, fully charge the battery, and if that doesn't fix it replace the battery.CANMAN

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[Hey CANMAN thanks for the reply. The battery is 3 weeks old from CTC and fully charged. The first drive with the new alternator (with a fully charged CTC battery still under warranty) caused it to boil and bulge the battery (a constant 17 volts at highway speed will do that). I then replaced that battery with the current battery thinking I had a battery problem as well. I do know that some (most) new cars these days do control the voltage demand with the ECU even with a built-in voltage regulator in the alternator. I did not know that the smart was also one of them. The technician confirmed this with his alternator repair parts computer software. The car starts fine and charges normally at idle (approx 13.7 volts with slight fluctuation) but with increased engine rpm the voltage output goes up to 17 volts which made me believe it was the built-in regulator at fault. The technician claims it is the ECU (SAM) that is causing this.cappytanjack

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[Hey CANMAN thanks for the reply. The battery is 3 weeks old from CTC and fully charged. The first drive with the new alternator (with a fully charged CTC battery still under warranty) caused it to boil and bulge the battery (a constant 17 volts at highway speed will do that). I then replaced that battery with the current battery thinking I had a battery problem as well. I do know that some (most) new cars these days do control the voltage demand with the ECU even with a built-in voltage regulator in the alternator. I did not know that the smart was also one of them. The technician confirmed this with his alternator repair parts computer software. The car starts fine and charges normally at idle (approx 13.7 volts with slight fluctuation) but with increased engine rpm the voltage output goes up to 17 volts which made me believe it was the built-in regulator at fault. The technician claims it is the ECU (SAM) that is causing this.cappytanjack

What was the resolution?

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