W221 2008 S320 CDI Starter Battery Charge Issue URGENT HELP REQUIRED!

[mbenz1]

Hi All,

My dad's '08 S320 (Small wheel base) has had an ongoing issue of the Starter battery not charging properly but recently the battery went dead so we decided to get the problem sorted as the battery is showing only 12.3V when engine ON. Alternator is fine as Consumer battery is charging at 14V.

My local MB Specialist diagnosed the car using STAR and it was showing open circuit voltage at the battery. So they did the following work as deemed necessary:

Wiring loom for starter battery A2215400850 (/64): a support bracket had fallen off hence a small section of the wire was rubbing against the body and caused the insulation to be cheesed off leading to sparking over time. So we got a used wiring loom from eBay (£25) and replaced it. The problem still persisted.

Next, the front left Fuse Box A2215400850 was replaced at the same time (again with a used unit off eBay for only £20) due to the short circuit of the wire with the body, hence causing internal fuses/connections within the fuse box to be blown.

Situation right now:

The specialist have said that unfortunately the starter battery is still not charging but they have managed to get 1 of the 2 wires going to the starter battery to provide just under 14V. This is a good improvement as before, both those wires were showing 12.3V.

Now, my specialist have requested it could be a power transponder/power supply unit or its corresponding wiring as STAR is not showing anything else besides the open circuit voltage.

They have suggested getting the car diagnosed only by Mercedes as they have technicians there who may be aware of this problem with the W221 model as the specialist don't want to charge me for work that has a 50/50 chance of being the solution.

I am happy to take the car to Mercedes, as I trust my specialist as I have been using them for the last 10 years and I understand that sometimes, rare electrical problems require further in-depth diagnosis which only Mercedes could offer with their highly technical and experienced technicians and internal rapport.

But before I take it to Mercedes, I would like to know if anyone is aware of any Software updates to the car such as the Information and Communication Central CAN bus like in the below thread post 12 and post 20 in particular. (I know this thread is for the facelift but wondering if it applies to pre-facelift)

221 - 2009 Need HELP please "Battery Not Charged" - MBWorld.org Forums

S-Class (W221) - 221 - 2009 Need HELP please "Battery Not Charged" - Hello i got my car week a go (W221 2009 4Matik) from first day on my screen was Red message Battery Not Charged couple my friend told me is AUX battery but problem is my car have only One battery in front is nothing in the...

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[mbenz1]

Issue solved. With the priceless help of DieselBenz, it appeared that the Voltage sensing wire which goes from Connector I3 at pin 1 in the engine pre-fuse box F32 to Connector 11A at pin 14 in the N82/1 power supply module in the boot, had a break in it as it was showing 0V with car off and also was showing no continuity. Due to this, the battery coupling relay in the F32 engine prefuse box was not closing, and was staying open all the time, hence the front battery was not being charged,

To check voltage at pin 14 of 11A, we removed the connector 11A at the N82/1 module (engine OFF), put the probe in the pin and measured voltage. When car is off, it should show battery voltage e.g. 12.5V. If it doesn't match battery voltage, it means there is a break in the wire or it has been cheesed off or some other issue.

To solve the problem, we cut the wire about 2 inches away from both connectors and ran a new wire from the N82/1 module to the F32 engine bay prefuse box. Problem resolved.

I would like to take this opportunity again to thank DieselBenz for his great support.

Hope this helps.

 

[m8JCG]

Issue solved. With the priceless help of DieselBenz, it appeared that the Voltage sensing wire which goes from Connector I3 at pin 1 in the engine pre-fuse box F32 to Connector 11A at pin 14 in the N82/1 power supply module in the boot, had a break in it as it was showing 0V with car off and also was showing no continuity. Due to this, the battery coupling relay in the F32 engine prefuse box was not closing, and was staying open all the time, hence the front battery was not being charged,

To check voltage at pin 14 of 11A, we removed the connector 11A at the N82/1 module (engine OFF), put the probe in the pin and measured voltage. When car is off, it should show battery voltage e.g. 12.5V. If it doesn't match battery voltage, it means there is a break in the wire or it has been cheesed off or some other issue.

To solve the problem, we cut the wire about 2 inches away from both connectors and ran a new wire from the N82/1 module to the F32 engine bay prefuse box. Problem resolved.

I would like to take this opportunity again to thank DieselBenz for his great support.

Hope this helps.

Hi There

I'm suffering the same issue on my S500 and i'm hoping your fix can solve it. Do you have a picture / diagram of the Connector 11A to show which pin is the no. 14? Also connector I3 and pin no.1?

Thanks,

 

[DSM10000]

Hi There

I'm suffering the same issue on my S500 and i'm hoping your fix can solve it. Do you have a picture / diagram of the Connector 11A to show which pin is the no. 14? Also connector I3 and pin no.1?

Thanks,

The OP hasn't been seen on the forum for over 2 years