CEM related issues: My diary of ongoing findings...

[Clan]

Originally Posted by Crazybob

Hi Clan.

Thank you for the information, parts acquired, replaced the com terminals in the green and brown plugs, left the 2 in the blue plugs. A quick drive and I'm still getting a warning light, it is "power system service urgent" with the red hazard triangle and a battery light, I also have a squeaky fan belt, surely that's not my alternator or battery though as I'm noticing that cruise control is disabling itself a little bit later after the warning comes up, also when I turn the ignition off and back on, that warning has gone. I will be replacing the 2 terminals in the blue plug, though I don't hold my Hope's up lol. Many thanks for your assistance so far it has been invaluable 👍

The blue plug is usually ok .. what are the fault codes ? Possible alternator problem

[Crazybob]

I don't have any codes I can read, I'm just going by the messages on the dash, I'm convinced I only had the fan belt replaced this year, but can't find an invoice to confirm, if I have, it shouldn't be squealing again surely

[Clan]

Originally Posted by Crazybob

I don't have any codes I can read, I'm just going by the messages on the dash, I'm convinced I only had the fan belt replaced this year, but can't find an invoice to confirm, if I have, it shouldn't be squealing again surely

no it shouldn't unless the alternator is charging too much and putting a heavy load on the belt .

[big yinn]

I'd check the battery voltage with the engine off and with it running.
12.6v off
14.4v running.
The alternators can catch fire, so it's worth checking.

[ThomasAO]

Originally Posted by Crazybob

I don't have any codes I can read, I'm just going by the messages on the dash, I'm convinced I only had the fan belt replaced this year, but can't find an invoice to confirm, if I have, it shouldn't be squealing again surely

Without reading through all the other comments to see if this was mentioned, i got this "power system - service urgent" on the dash with a red battery symbol. it disappeared for a wee while and then came up again. i connected to Vida Dice and no faults were shown

Reading on battery when engine is off was 11.96V
Reading when engine is on was 11.61V which should have been 14V
Voltage coming out of the main terminal on alt should be 14v, if its not it could be your alt

I replaced the alternator and it resolved the matter.

[Crazybob]

Soooooo, fanbelt replaced, they tested my battery and alternator, both are fine, apart from having to pop a shim on my positive battery post it is looking like we're back to the CEM

[Crazybob]

Bit of an update, it seems that I can drive for ages on a fast road with no issues, as soon as I'm in a 30 or 40 limit I have around 5 mins of driving till the "Power system service urgent" message appears. No issues with the way the car runs, I'm tempted to pop a multimeter on it to get a number for the voltage rather than rely on the garage telling me it's fine

[Batlamb]

I had similar problems and went to Volvo Diagnostics. Made the car run a lot better https://volvodiagnostic.com/

[Crazybob]

Originally Posted by big yinn

I'd check the battery voltage with the engine off and with it running.
12.6v off
14.4v running.
The alternators can catch fire, so it's worth checking.

Hi,
Finally got some numbers, I measured across the battery terminal clamps.
Ignition off - 12.61
Running- 14.55 ( you suggested 14.4, is this overcharge or ok?)

[Clan]

Originally Posted by Crazybob

Hi,
Finally got some numbers, I measured across the battery terminal clamps.
Ignition off - 12.61
Running- 14.55 ( you suggested 14.4, is this overcharge or ok?)

yes that's all quite healthy , the charging voltage alters a little due to the temperature