W221 S320 CDI Starter Battery Wiring Loom WIS/Diagram Needed

[mbenz1]

Hi All,

Hope you are all well in this challenging time we are facing.

I require some help for my dad's 2008 S320 CDI SWB.

Problem: Weak starting caused by lack of charge entering the starter battery due to wiring issue. Local indie said the car shows the following error:

901A The charge line to component G1/4 (starter battery) has Open circuit.

He has advised getting a new wiring loom part number A2215400232. I have got this from eBay used and want to see if it is something I can attempt to replace. I am not that bad with cars and have done various jobs over the years.

I would be grateful if anyone can provide a WIS or diagram of this wiring loom so I can know what is required to be removed etc.

Thanks,

 

[Diesel Benz]

Does your indie assume all the copper being worn out from that thick cable? Are you sure it isn't a contact issue or something like that?

Better to be careful when working with these high current lines.

 

[zipdip]

Well I suppose your local guy checked to see how much voltage was going into the battery with the engine running,and it was way down,only you know how good this guy is,did he check the earths,still you have bought a wiring loom,to be fair I would get a mobile auto electrician to check it and then fit the loom,in all the time I had a W221 it never gave me any problems except the big battery in the boot decided to pack it in.

 

[mbenz1]

Does your indie assume all the copper being worn out from that thick cable? Are you sure it isn't a contact issue or something like that?

Hi, thanks for your reply and attached doc. Yes, he has checked as much as he can without taking anything off and he pans it down to the whole loom, as h thinks there is a loose contact or break in the wire, hence why he has said that worse case scenario is the wiring loom. I have got one off eBay for only £24 so worth a gamble for sure!

I appreciate your attached doc but that is way above my electrical knowledge! Do you have a WIS or something similar which is more easy to understand please?

Better to be careful when working with these high current lines.

Well I suppose your local guy checked to see how much voltage was going into the battery with the engine running,and it was way down,only you know how good this guy is,did he check the earths,still you have bought a wiring loom,to be fair I would get a mobile auto electrician to check it and then fit the loom,in all the time I had a W221 it never gave me any problems except the big battery in the boot decided to pack it in.

Yep, its only receiving 12.3 V on engine ON condition, as mentioned, the loom only cost me £25 used so well worth it if I do get him to check further and dismantle parts etc..

 

[mbenz1]

Does your indie assume all the copper being worn out from that thick cable? Are you sure it isn't a contact issue or something like that?

Better to be careful when working with these high current lines.

Hi, thanks for your reply and attached doc. Yes, he has checked as much as he can without taking any parts off and he pans it down to the loom as he says it can be a loose contact or break in the wire. Hence, why he has said its a good idea to have a new loom handy when attempting to solve the problem. I have got one off eBay for only £25 so well worth it!

Do you have a WIS or similar by any chance, as the circuit diagram is way above my electrical knowledge! Thanks,

 

[mbenz1]

Problem 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 pin 14 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. In our case, it was showing basically 0V.

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 using 0.75mm2 flexi cable and splice connectors. Problem resolved.

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

Hope this helps.