Power system service warning light with no fault code

wingers · May 28th, 2020, 11:41

What could cause the alternator to not charge and there to be a power system service warning light, but no fault codes in the ecu.
This is a 2005 v70 by the way.

Initially there was an alternator code cem-dd30 (and I think cem-dd21). An alternator change fixed those, but not the dash warning. At that point it was charging at 13.5v but no more than that. It's now at a garage to investigate further and apparently has stopped charging at all (11.7v) but still no fault codes.

They are saying it's the end of the road as it will be too expensive to fault find. Not sure if anyone else has already been down this road though...

Wingers

Longhouse21 · May 28th, 2020, 12:36

From what I can find it appears it may just be a short or open circuit in the LIN wiring and there also appears to be a particular suspect. Read here: https://forums.swedespeed.com/showth...RVICE-REQUIRED

wingers · May 28th, 2020, 13:19

The lin system doesn't have any error codes either now though.
The garage have found a bit of corrosion in one of the cem connectors (not the alternator related one) but it's thought possible that the whole cem could be bad. That might be the next step but there aren't any other signs of issues with that so it seems unliukely for now.

Wingers

XC70Bob · May 28th, 2020, 15:28

So this may have already been checked but just in case.

2005 was the year that a lot of electrical changes took place , this includes the alternator.

pre 2005 the alternator had a red/white wire going to the L terminal on the alternator and I believe it was just a straight 12V supply.

post 2005 the alternator had a green/white wire going to the L terminal on the alternator and it now carried a signal rather than just a straight 12V.

putting the wrong alternator on the car leads to no charging and probably a warning message.

As 2005 was the change over year you need to check which colour wiring you have going to the L terminal on your alternator to be sure you fitted the right alternator.

oragex · May 28th, 2020, 20:59

As above, be sure you got the correct regulator https://www.youtube.com/watch?v=4KvF0Z1u7FE
See on Fcpeuro.com the right code

Otherwise, a bad battery will no longer accept a charge. And of course, there may be a bad cable, even the small connector at the alternator can go bad

May 28th, 2020, 11:41	#1
wingers New Member Last Online: Aug 22nd, 2022 20:22 Join Date: Jul 2008 Location: Northampton	Power system service warning light with no fault code What could cause the alternator to not charge and there to be a power system service warning light, but no fault codes in the ecu. This is a 2005 v70 by the way. Initially there was an alternator code cem-dd30 (and I think cem-dd21). An alternator change fixed those, but not the dash warning. At that point it was charging at 13.5v but no more than that. It's now at a garage to investigate further and apparently has stopped charging at all (11.7v) but still no fault codes. They are saying it's the end of the road as it will be too expensive to fault find. Not sure if anyone else has already been down this road though... Wingers

May 28th, 2020, 12:36	#2
Longhouse21 Master Member Last Online: Today 21:53 Join Date: Jan 2011 Location: Warrington	From what I can find it appears it may just be a short or open circuit in the LIN wiring and there also appears to be a particular suspect. Read here: https://forums.swedespeed.com/showth...RVICE-REQUIRED __________________ Current cars: 2003 V70 D5 SE (MY2004); 2012 CRV 2.0i V-TEC; Gone but not forgotten: 2001 Honda HRV; 1989 VW Polo C Mk2; 2000 Honda Civic VTi Aerodeck ; Cavalier SRi; Cavalier LX; 1971 Triumph Spitfire Mk3; 1963 Triumph Herald.

May 28th, 2020, 20:59	#5
oragex Premier Member Last Online: Jul 26th, 2021 21:24 Join Date: Jun 2013 Location: Coldnada	As above, be sure you got the correct regulator https://www.youtube.com/watch?v=4KvF0Z1u7FE See on Fcpeuro.com the right code Otherwise, a bad battery will no longer accept a charge. And of course, there may be a bad cable, even the small connector at the alternator can go bad __________________ Several Volvo Repair Videos https://www.youtube.com/playlist?lis...ECTts0FSVSOT_c

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May 28th, 2020, 13:19	#3
wingers New Member Last Online: Aug 22nd, 2022 20:22 Join Date: Jul 2008 Location: Northampton	The lin system doesn't have any error codes either now though. The garage have found a bit of corrosion in one of the cem connectors (not the alternator related one) but it's thought possible that the whole cem could be bad. That might be the next step but there aren't any other signs of issues with that so it seems unliukely for now. Wingers

May 28th, 2020, 15:28	#4
XC70Bob XC70 SE lux D5 Last Online: Feb 25th, 2024 14:34 Join Date: Jan 2011 Location: Mansfield, notts	So this may have already been checked but just in case. 2005 was the year that a lot of electrical changes took place , this includes the alternator. pre 2005 the alternator had a red/white wire going to the L terminal on the alternator and I believe it was just a straight 12V supply. post 2005 the alternator had a green/white wire going to the L terminal on the alternator and it now carried a signal rather than just a straight 12V. putting the wrong alternator on the car leads to no charging and probably a warning message. As 2005 was the change over year you need to check which colour wiring you have going to the L terminal on your alternator to be sure you fitted the right alternator.

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