What is your EDC from the VIN.

 

It’s 9HR

 

PEUGEOT 308 1.6 HDiF, DV6C (9HR) 2010 - 2013

DTC U1218 Communication with the power supply control unit
Haynes is depressing after that about this one, showing only this for E6 which is usually the slave unit (engine fuse box) and commination is usually from BSI, but could be with Engine ECU or ABS even (don't know at this stage without the wiring diagrams)

Which means Peugeot Wiring Digrams and whole VIN is needed, the DAM/RPO would also help.

Before we go to this path, talk to me about the voltage fluctuation(s) you have, what are they, where are they measured.

 

Okay so the photos were just for me to be sure, we did don't have oil, or oil like products, entering the alternator, this kills them (it appears no oil). Does not rule diode pack however, these usually kill the battery from out-of-phase charging, which can be problematic, if you try new battery, and this problem exists, the battery light *may show very faintly when driving. When a diode blows fully, the battery light will be fully on. The diodes don't always blow, but they start to allow voltage through the diode rectifier circuit, the wrong way (also called wrong gate) and hence the name, out-of-phase charging is given.

*you tend to be able to notice this, best when at nighttime.

Given it is a smart alternator, this maybe (seems like it would be) within normal operation as well, you may have removed the wire that controls the feed of voltage, in which case defaults the operation, not stops it. You would have needed to remove B+ wire, and doubt you did this. Refer to 1021 in the diagrams below.

VF34C9HR8BY063540 (ssg.asia) this gives you OEM part numbers and exploded views.

Vehicle characteristics

​ Model: 308 Body: FIRM 5 DOOR SALOON Engine: DV6C TURBO DIESEL Transmission: STT 6-SPEED PILOTED MANUAL GEARBOX

PEUGEOT 308 1.6 HDiF, DV6C (9HR) 2010 - 2013
DTC U1218 Communication with the power supply control unit

Engine (with stop/start) Starting

PSF1 (Engine Fuse Box)

BFDB

1031

PEUGEOT ALL MODELS WIRING DIAGRAMS - GENERAL
PSA Electrical Diagrams - Wiring & Symbols Codes Index - French Car Forum

 

So when driving normally or idling the battery is showing between 12.5-12.8 volts. But when on overrrun or activating wipers the voltage goes back up to 14.8. had the car 6 years and it has never done this. I unplugged the alternator briefly while running and the voltage also went up to 14.8 so surely can’t be an alternator issue as it has the ability to produce correct voltage.

I also have a local fault code in the ECU which is “0303 Configuration” which won’t clear. I also notice the battery current fluctuating from amps to showing 4 random numbers and letters?

 

Well, PM or publish the VIN and look into this tomorrow, heading to bed. That does sound strange, can you post a photo not too close of the engine near the alternator.

 

VIN is VF34C9HR8BY063540 cheers.

 

Wow where do you find all this? Cheers for that I’ll have a good look through it. Yeah I’ve never had any battery lights on or any other fault so tempted to just leave it until something actually happens if it ever does as I’ve quoted just under £1000 for a new alternator.

Cheers 👍

 

Peugeot Workshop Manuals - Sedre. Took me a while to figure it out and where to find information, not like any manuals from non-French manufacture. Generally speaking, the Japanese brands win for their layout vs french way ~imo.

other fault

The fault recorded is to do with control of PSF1 (slave) to BSI (master) you could try clearing it and watch to see if it comes back. A low battery or high battery state can sometimes trigger this or other DTC, just wanted to rule that out.