Bosch M.F Regulator

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Bosch M.F Regulator

Postby Liteace » Tue Mar 05, 2013 8:09 pm

Got here a 05 2.2 Zafira, the battery was replaced by the owner about 6 weeks ago due to low battery starting problems, its again got starting problems, I tested battery voltage with engine running and was only getting a little over 12 volts with a load on, headlamps, heater blower


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I took the alternator off, most of the time I just give the alternators to alternator\starter repair guy and let him sort it out, this one I tested it on the benchwith a variable speed electric drill, 1st was ripple test, looks ok to me what do you guys think

bench ripple.png

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Next volatge:

VS bench test.png

VS bench test.psdata
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On that test the red trace is the test\battery lamp, you can see just after 12 sec's the lamp go out and start charging but only at just under 13 volts, as I increased the speed the voltage increased to just under 14 volts but only for about 6 sec's then starts dropping off, slowed it right down till the battery\test lamp started flashing, 29 sec's.
The minimum voltage is just over 12.5 volts, the max is just over 13.5 volts, this alternator, according to the bosch part number its fitted with a multi function regulator with battery voltage monitoring
Here is another bench test with a battery that did not have enough in it to start an engine, again red trace is batter\test lamp. You can see the min voltage is just over 11.5 and max is just under 13.5

bench test 2.png

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So the question is, is this reg working as it should or should we be seeing a higher regulated voltage at a lower speed ?
Last edited by Liteace on Wed Mar 06, 2013 7:10 pm, edited 1 time in total.
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Re: Bosch M.F Regulator

Postby KimAndersen » Wed Mar 06, 2013 2:59 pm

Hi Liteace

I don't have any first hand experience with the particular system fitted on a Zafira 2.2 engine.

What I know, is that General Motors (GM) at around 2004/2005 launched a alternator system called Regulated Voltage Control (RVC) , which is used in a lot of GM cars.

The system are fitted with a current sensor around the earth or the positive cable at the battery and the RVC system also use calculated battery temperature to determine what the perfect voltage to supply the battery with is.

It´s more complicated to say what the correct regulated voltage at the battery should be, when there are more parameters to take account for.

I think you should identify what system there are installed in your Zafira before you start to diagnose it.

I have looked at your ripple test and I think it looks right.

Here at the end, have you checked your ECM/PCM for any diagnostic trouble codes ?

I know, it aint much that I can contribute with.

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Location: Denmark

Re: Bosch M.F Regulator

Postby Liteace » Wed Mar 06, 2013 7:30 pm

I did identify what system is installed in the Zafira before I started to diagnose it, Its a bosch system

"according to the bosch part number its fitted with a multi function regulator with battery voltage monitoring"

I always check ECM/PCM for any diagnostic trouble codes and there was none.

I asked becuase of all the cac that bosch says about this reg:

"Monolithic regulators have largely superseded hybid regulators as standard equipment for monder vehicles. Monolithic regulators are being inctreasingy employed with a wide range of new functions, these so-called multi-fuction regulators (MFR) are now fitted to all new bosch compact alternators.
Compared to conventional regulators, multi-fuction regulators feature the following additional functions:
-Battery monitoring (sensing)
-Fault diagnostics
-Start load responce
-Operation load responce
-capacity utilization monitoring
-Engine management support"

As I said what a load of Cac, if this had been a norm reg or I had not read all that I would have not hesitated in changing it . I put a new reg on today and its now charging at 14.2 volts, as for "Fault diagnostics" where's that then, did it give any indication to the driver that the battey was not charging, nope, well it did when the vehicle did not start !!
I didnt have time to scope it as it was an onsite job and i had to hunt about for the correct size belt
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