Battery light (new battery and new OEM Volvo Alternator) error code DD30

2birds · Dec 5, 2023

Hello everyone!

I was wondering if someone can chime in with the problem I’ve been trying to figure out in days!

I recently bought a 2007 S60 2.5T that runs flawlessly. However, there was this red “System power Urgent” warning with battery light. So I quickly assumed it was the alternator even tho previous owner mentioned the light was on for 3 years.

fast forward after installing a original Volvo alternator, the light was still on so I brought it to my local mechanic and had it scanned for codes.

there were a few that was on but after reset only 2 quickly appeared again.

Communication with the Alternator Control Module (ACM). Signal Missing

Alternator Control Module (ACM). Voltage Too High, B525412

I checked that the regulator wire was inserted properly and it was.

quick note current voltage from battery post is 13.5 - 13.6 while car is at idle

Regulator wire voltage measured with volt meter = 6.5V while car is in ON position (engine off)

Would this me a CEM problem or is there something I should look for before replacing the whole module?

Thank You in advance!

wagonswede · Dec 5, 2023

There are two different alternators (different voltage regulators) for the same engine depending on year make of the car. 03-04 does not communicate with the CEM. The 05-08 does.

Check so that you don't have the wrong type.

2birds · Dec 5, 2023

thanks so much for the reply! I actually have triple checked and I do have the right one for 2005+ regulator part number:

F00MA45212

volvogod · Dec 5, 2023

The average LIN voltage is 7-8 volts. 6.5 volts is probably OK.
6/25 = starter
6/26 = Alternator
Since you have 6.5 volts at B1, I would assume that the CEM is sending out the correct
LIN voltage and signal to the ACM. Not knowing the code, I picked this one for voltage too high.
I am not sure what is causing the message. Did you install a new or used alternator?
The bottom pics are the CEM. You could remove the wiper cowl, top CEM cover.
Inspect both CEM connectors/pins B and C for any water damage or corrosion.

Check out xemodex.com about this issue.
Available Services for 2005-2014 Volvo Central Electronic Module | XeMODeX Inc.

2birds · Dec 5, 2023

volvogod said:
The average LIN voltage is 7-8 volts. 6.5 volts is probably OK.
6/25 = starter
6/26 = Alternator
Since you have 6.5 volts at B1, I would assume that the CEM is sending out the correct
LIN voltage and signal to the ACM. Not knowing the code, I picked this one for voltage too high.
I am not sure what is causing the message. Did you install a new or used alternator?
The bottom pics are the CEM. You could remove the wiper cowl, top CEM cover.
Inspect both CEM connectors/pins B and C for any water damage or corrosion.

Check out xemodex.com about this issue.
Available Services for 2005-2014 Volvo Central Electronic Module | XeMODeX Inc.
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Thanks for all the info! I find it weird that only the alternator is having an issue according to the scanner. Is there a possibility that my regulator is defective?

zak · Dec 5, 2023

Some of the alternators had a freewheeling clutch (built into the drive pulley I think). This might have been a manual transmission only kind of thing, but maybe if your car is expecting a freewheeling alternator and you have a fixed drive system or vice versa, could lead to unexpected voltage excursions. Just a thought

2birds · Dec 8, 2023

Just an update, I have gotten the CEM checked and there is nothing wrong with it. I am completely stuck now

Battery light (new battery and new OEM Volvo Alternator) error code DD30

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