Charging error

[BlueMeany]

Mk5 Mondeo (15 plate diesel auto) has started to pop this error up after starting...

Have taken it in to two garages, both not 100% sure. No starting issues, everything working fine from what we can tell.

Being told to try a new battery, but diagnostics don't indicate a particular problem with battery stats, or alternator either.... Anyone with any suggestions? I've tried disabling BMS in forscan, to try if sensor was at fault, but still shows. I've since enabled it again.

 

[Tizer]

There is a PID for Current that you can Live Monitor, amongst other things with FORScan.

With Conventional Charging the Net Current that it shows starts off quite high at a start and settles down to just a few Amps after a few minutes.

There is also a PID in the PCM for the Generator Field Current Duty Cycle that you can Live Monitor, there may be other ones too that might be useful.

I'm not certain what that Fault Code actually refers too.

[TomsFocus]

The Mk5 Mondeo uses a separate current monitoring sensor around the alternator cable terminal.

This is not the same as the state of charge sensor fitted over the negative battery terminal.

There are separate PIDs for these in Forscan.  One reads current in amps, the other reads SOC as a percentage.

If there are no amps showing on the live data.  Check the BCM configuration to make sure the charging type is set to LIN, not PWM.

If there are still no amps showing, check that the sensor is plugged in securely.  If it is, then it's looking like a new sensor needed.

[BlueMeany]

On 11/20/2023 at 10:36 AM, TomsFocus said:

The Mk5 Mondeo uses a separate current monitoring sensor around the alternator cable terminal.

This is not the same as the state of charge sensor fitted over the negative battery terminal.

There are separate PIDs for these in Forscan.  One reads current in amps, the other reads SOC as a percentage.

If there are no amps showing on the live data.  Check the BCM configuration to make sure the charging type is set to LIN, not PWM.

If there are still no amps showing, check that the sensor is plugged in securely.  If it is, then it's looking like a new sensor needed.

Thanks for the info.

I've run some PIDs this afternoon, following a battery change (error still showing).

The SOC started around 94% with amps showing 13-14, then as it was ticking over for a few minutes, this increased to around 98% with a lower amps showing. Presume that means the sensor on alternator is working?

I reset the DTCs, and in the past these have come back - however this time the BCM module has no PID but there is one under PCM (P0620:13-2F) 

[TomsFocus]

Those live readings do appear to show the alternator sensor working correctly.  

Not sure what to suggest now I'm afraid.

[BlueMeany]

I've read, and heard, elsewhere that there is a yellow wire on the alternator (possibly to PCM) which corrodes and breaks. Do you think this may be the issue? Also, sometimes just a blown fuse! Would you know which fuse to check?

[TomsFocus]

Hmm, that P0620 code suggests a voltage issue rather than a current issue.  That will be one of the wires from the plug on the alternator itself to the PCM.  It may be yellow but you'd have to double check that.

Open circuit should be easy enough to detect even with a basic continuity test.  Though I'm not sure how accessible the PCM plug is on the Mondeo.

Looks like fuse F46 (10amp) for alternator.  There should be a fuse list in your handbook to double check.

[BlueMeany]

On 12/31/2023 at 8:00 PM, TomsFocus said:

Hmm, that P0620 code suggests a voltage issue rather than a current issue.  That will be one of the wires from the plug on the alternator itself to the PCM.  It may be yellow but you'd have to double check that.

Open circuit should be easy enough to detect even with a basic continuity test.  Though I'm not sure how accessible the PCM plug is on the Mondeo.

Looks like fuse F46 (10amp) for alternator.  There should be a fuse list in your handbook to double check.

That's what everyone we have taken it to suggest. 

It's now booked in with an auto-electrician in couple of weeks. I've given him the history and codes etc... I'm just a bit concerned that he said even though I've been advised wiring, he said it's also likely to be alternator.

Is there anything I can request from him to ensure that he isn't going to rip me off and charge for an alternator but fix a wire? I'd like to think he wouldn't, but want to be absolutely certain of everything... especially as all garages that have checked (that aren't auto electricians) have said it's a wiring issue.

 

[TomsFocus]

Hmm, I see what you mean but I don't think there is anything you could do to prevent a potential upsell unless you stand there watching him complete the tests.

If you're concerned he may charge for an alternator but not fit one then you can always put something unique on yours...dab of paint or UV pen for example.