W211 e320 alternator driving me nuts

[jamesr181]

Need help guys. W211 e320 2004. Changed alternator as had fault codes for alternator. Started up, got 14.1v running but still getting red battery symbol on dash intermittently. When idling the red battery symbol pops up and convenience disabled, leave running then convenience enabled. All this while the voltage is saying 14.1v

Any ideas? The alternator is a recon from a very good place by me.

 

[AMGeed]

Check the voltages on both your main battery in the boot and the aux battery under the pollen filter.
Both should be reading 12.6v+ fully charged. If not, get them charged and see if the red warning disappears.

 

[pgh13]

How old is the battery? Just swapped mine, because although the car always started, I was getting convenience function warning every day. Also, how is the auxiliary battery? That used to give me a red warning when it was fading

 

[jamesr181]

Check the voltages on both your main battery in the boot and the aux battery under the pollen filter.
Both should be reading 12.6v+ fully charged. If not, get them charged and see if the red warning disappears.

View attachment 82844

Already checked both mate, both are at good levels. It's very intermittent, I've got a bcm and a k57 relay coming. Going to try that and see if that does it. The fact that I've got correct charging voltage at the batteries is what's confusing me.

 

[jamesr181]

How old is the battery? Just swapped mine, because although the car always started, I was getting convenience function warning every day. Also, how is the auxiliary battery? That used to give me a red warning when it was fading

Both batteries are approx 2 yrs old. Front is an exide and the rear is Varta AGM.

 

[Doug1234]

Is the charging system controlled by the ecu / lin system ?.
I see lots of posts on a Jeep forum I frequent ( Grand Cherokees like mine have the Mercedes om642 with the Lin system ) and most of the alternator posts are like yours with the alternator charging ok but dash warning light still on.
The reason for this is the new alternators these owners fit have an incorrect voltage regulator that does not function with the Lin system , basically the ecu cannot communicate with the alternator regulator so the warning light stays on.

 

[tpn]

Is the charging system controlled by the ecu / lin system ?.
I see lots of posts on a Jeep forum I frequent ( Grand Cherokees like mine have the Mercedes om642 with the Lin system ) and most of the alternator posts are like yours with the alternator charging ok but dash warning light still on.
The reason for this is the new alternators these owners fit have an incorrect voltage regulator that does not function with the Lin system , basically the ecu cannot communicate with the alternator regulator so the warning light stays on.

That is probably the problem. A family member got a recon alternator on his BMW X5 and is experiencing the exact same problem. He is getting the old alternator rebuilt

 

[ajlsl600]

Makers try to direct one to origional type alt.

 

[jamesr181]

Is the charging system controlled by the ecu / lin system ?.
I see lots of posts on a Jeep forum I frequent ( Grand Cherokees like mine have the Mercedes om642 with the Lin system ) and most of the alternator posts are like yours with the alternator charging ok but dash warning light still on.
The reason for this is the new alternators these owners fit have an incorrect voltage regulator that does not function with the Lin system , basically the ecu cannot communicate with the alternator regulator so the warning light stays on.

Hmmmm, that's not too bad a shout mate.

 

[jamesr181]

Right guys. Both batteries are showing 14.1v while the car is running on the multimeter and on the icarsoft. Both batteries are fairly recent and in good order.
Got a k57/2 relay and bcm just in case and the problem still persists. Albeit still intermittently where I get red battery symbol and conveniences disabled and after a short time the conveniences come back. All while car is still 14.1v. Am I right in thinking it's more than likely the voltage regulator?
I'm struggling beyond that.