W166 Eco start stop - Not operating
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Ml 250 W166
W166 Eco start stop - Not operating
Hello, I have a 2013 ML 250 W166, the Eco start stop is not working any more, I tried replacing the auxilliary batery and it is still the same, the green light on the button only comes on with the key before iturning gnition to start and then the green light goes out when you start up the engine, it is off blank no green or amber. and the start stop doesnt operate, any ideas why or possible solutions. Thanks
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2008 E350, 2012 ML350, 2014 E350, 2015 ML350
Have you scanned the car for codes? Sometimes there are some w/o reporting a CEL in the cluster.
If the problem was the auxiliary battery very likely you would have seen a message in the cluster "Auxiliary Battery Maflunction" or the like.
For the start/stop ECO feature, the car checks several systems (including the AUX battery), then decides if it is safe to stop the engine. It may be the main battery, but it can be something else. If you can find a battery place with a MIdtronics tester, or a good "health battery" checker, the better.
If the problem was the auxiliary battery very likely you would have seen a message in the cluster "Auxiliary Battery Maflunction" or the like.
For the start/stop ECO feature, the car checks several systems (including the AUX battery), then decides if it is safe to stop the engine. It may be the main battery, but it can be something else. If you can find a battery place with a MIdtronics tester, or a good "health battery" checker, the better.
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Ml 250 W166
Thanks , yes I had the codes checked , a few spurious ones not indicative, I will try again, so far there is no aux batt ,malfunction warning , all that appears well, it may be a low main battery, what should the static voltage be reading ? ... I dont want to take it to Benz here as they make a mountain out of a molehill and commence their job creation.........last time I went to MB there for their self imposed software update ..which I had to pay for their stupid corrrective update which should have been free as they cocked up.......they then wanted to pull out my entire Blue tech adblue system to clean it... and I said no... and the car has been fine since then a year and a half later.....I can live without the ECO , but would be nice to get it working if its an easy fix ....there is a good German car indy garage called Bavaria in Aberdeen , I usually go there as they know more than the technicians at MB and dont mess around ......cheers
Last edited by beveridgio; Oct 5, 2021 at 05:03 PM.
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2008 E350, 2012 ML350, 2014 E350, 2015 ML350
with a digital multimeter, the voltage at the battery posts (disconnected) should @12.4-12.8V. Anything below 12V and the battery is discharged and should be recharged.
However, a good voltage is required for a good battery but not sufficient. The effective CCA (Cold Crank Amperage) rating is what really matters and a digital voltmeter does not give you that. That is why you need a health battery tester.
If your main battery is in good health, you must probably need to read the documentation for your car. It usually describes what system the ECO checks before shutting the car off: coolant temperature, battery charging system, battery internal resistance (or similar), ambient temperature, etc..
However, a good voltage is required for a good battery but not sufficient. The effective CCA (Cold Crank Amperage) rating is what really matters and a digital voltmeter does not give you that. That is why you need a health battery tester.
If your main battery is in good health, you must probably need to read the documentation for your car. It usually describes what system the ECO checks before shutting the car off: coolant temperature, battery charging system, battery internal resistance (or similar), ambient temperature, etc..
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Ml 250 W166
Many thanks for the knowlege and information, I will investigate further. Do you know what the alternator charging voltage should be from the regulator to the battery terminal? , I was thinking as the green light goes off when starting up it may be too low to charge the battery to the voltage needed for the ECO Start Stop and the battery may therefore be charged at too low a voltage. I will measure and check the open circuit voltage as you suggest as well as the connected voltages and with the engine running also check the voltage when charging. Thanks for your suggestions Best Regards
Last edited by beveridgio; Oct 6, 2021 at 03:27 AM. Reason: update
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From: US
2008 E350, 2012 ML350, 2014 E350, 2015 ML350
I am new to this, but until now I have learned these ECO cars have a smart charging algorithm that may vary charging voltage from 12.x->14.8V. Depending on what part of the charging algorithm you are measuring, you may find any of those values.
However, it seems you can force it to be at its maximum charging cycle when your headlights are ON manually (not automatically), and AC on as well. Let me find out a few threads (some are long) discussing the charging algorithm (but for the W212).
https://mbworld.org/forums/e-class-w...ml#post8360723
https://mbworld.org/forums/e-class-w...ging-algo.html
https://mbworld.org/forums/e-class-w...ml#post8346538
However, it seems you can force it to be at its maximum charging cycle when your headlights are ON manually (not automatically), and AC on as well. Let me find out a few threads (some are long) discussing the charging algorithm (but for the W212).
https://mbworld.org/forums/e-class-w...ml#post8360723
https://mbworld.org/forums/e-class-w...ging-algo.html
https://mbworld.org/forums/e-class-w...ml#post8346538
Last edited by JCM_MB; Oct 6, 2021 at 08:09 AM.
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