SMax Battery Light permanently on
Discussion
Hello,
My S-Max 2.0TDCI, 59 plate, 56K mileage, good nick, well serviced has started to show a permanent battery light. It does not flicker like an alternator charging problem but remains permanently on.
So I checked battery using a battery and alternator charging tester (the ones with LED's). Showed 3 lights, all good I thought. Then I put front and rear window heaters on to put some load through the circuitry.....3 lights went down to 2, so I thought OK, needs a new battery after 9 years not unreasonable.
I bought a new lifetime Yuasa battery, fitted it and closed the bonnet. Went for a run, and hey presto light came back on.
I then checked on idle using Multimeter voltage at battery terminals, showed 13.1V, which I think means alternator is charging.
I have read there are some problems with Ford's and the PCM module, does anyone know how to check this before I go buying an alternator which could also end up being a wild goose chase?
In my other cars over the years, the battery light used to flicker when the alternator was on its way out......but this is just a battery light permanently on after about 500 yds of driving.
I have a foxwell NT154 Pro, but this doesn't pick any fault codes up.
Any help would be appreciated.
On another note, I now need to charge the battery, on the S-Max it is buried away under the front scuttle........can I connect the charger directly to the Positive (red) terminal and the black to the -ve terminal or does modern electrickery necessitate removing the battery (which is a REAL pain).
Sorry for dumb questions, but been a few years since I messed with the car and technology has massively moved on.
Cheers,
Chris
My S-Max 2.0TDCI, 59 plate, 56K mileage, good nick, well serviced has started to show a permanent battery light. It does not flicker like an alternator charging problem but remains permanently on.
So I checked battery using a battery and alternator charging tester (the ones with LED's). Showed 3 lights, all good I thought. Then I put front and rear window heaters on to put some load through the circuitry.....3 lights went down to 2, so I thought OK, needs a new battery after 9 years not unreasonable.
I bought a new lifetime Yuasa battery, fitted it and closed the bonnet. Went for a run, and hey presto light came back on.
I then checked on idle using Multimeter voltage at battery terminals, showed 13.1V, which I think means alternator is charging.
I have read there are some problems with Ford's and the PCM module, does anyone know how to check this before I go buying an alternator which could also end up being a wild goose chase?
In my other cars over the years, the battery light used to flicker when the alternator was on its way out......but this is just a battery light permanently on after about 500 yds of driving.
I have a foxwell NT154 Pro, but this doesn't pick any fault codes up.
Any help would be appreciated.
On another note, I now need to charge the battery, on the S-Max it is buried away under the front scuttle........can I connect the charger directly to the Positive (red) terminal and the black to the -ve terminal or does modern electrickery necessitate removing the battery (which is a REAL pain).
Sorry for dumb questions, but been a few years since I messed with the car and technology has massively moved on.
Cheers,
Chris
cnprior said:
I then checked on idle using Multimeter voltage at battery terminals, showed 13.1V, which I think means alternator is charging.
Not really. Give it a few revs, and it should be over 14v. 13v is barely above a fully charged battery's rest voltage, and certainly won't put much into the battery.cnprior said:
In my other cars over the years, the battery light used to flicker when the alternator was on its way out......but this is just a battery light permanently on after about 500 yds of driving.
It's not a "battery light". It's a charge light. Or, rather, a lack-of-charge light. It tells you nothing about the battery itself, and everything about whether the battery is being charged.On older cars, it was lit when current was passed to the alternator to "turn it on", and went out if the alternator was producing charge. It'd flicker if it was borderline. On modern stuff, especially if the alternator's managed by the ECU, it's simply turned on and off by the ECU when it decides that the charge is dicky - so no flickeriness or dimness.
This is a Ford Smart charging issue which is to do with the Alternator not being told by the PCM how much load to output. The PCM should instruct the Alternator to increase its nominal (14.3 Volts) output up to (14.7 Volts) or higher when there is load on the electrical system. This is to assist the battery powering all the circuits etc.
There could be three reasons why the Alternator is kicking out 13.1V. the PCM com or monitor line is damaged so the PCM cannot tell what the Alt is producing, or to produce more if needed. 2. The PCM battery monitoring circuit is fried (unlikely), or finally and most likely, 3. The smart part of the alternator isn't listening to the PCM's instructions so defaults the output to 13.1V so it does t damage the battery.
To diagnose completely, you'd need to hook a multiline digital volt meter up to all the relevant signal lines & the + & - lines and monitor the signals on a Laptop with the engine running. This will show if the PCM is talking to the Alternator and what the response is from the Alt. If it is talking but there is no change in charge output, then the alternator is goosed.
If there isn't a signal from the PCM, check the harness is good and if it is......I don't know enough to say it but it could be a new PCM.
My 2017 2.0TDi SMax's heated windscreen has worked about 5 times since I owned the car. Last Xmas, Ford had my car on 5 occasions (3 different dealers). 2 days & nights at one and they still couldn't get their fault machine to diagnose the car as that is impossible if the battery charge "isn't above 75%." So, I took my car home, charged the battery fully and drove it back to the dealership on the 3rd day.
Their battery tester confirmed the battery was above 95% charge, the car only saw 64% charge. So, the dealership charged it overnight (they didn't believe me it seems) and found the car only saw 69% charge the following morning.
That was 14hr+ of charge after I had charged it at least 16hrs at home. Ford emailed Ford Germany (the SMAX Boffins apparently) and were told it's a common fault with that engine SMax and 1 version of Transit vans. Their response, charge the car with the ignition on but not running. Sure enough, on the 4th day after another night of charging, the car showed 78% charge and showed no faults.
The heated windscreen also worked again so "no fault found" was Ford's response. My reply was that their clearly was a fault as the cars SMART battery system should be able to see a fully charged battery if there is one. So, after much hassle, Ford Germany said to change the battery (as a trial only) and tell the PCM that the battery had been changed. This should give a default battery charge % of 85% to enable all systems and diagnosis if there were other faults........low and behold......it didn't. The system showed a charge less than 70% even though the dealer had charged the new battery to max prior to fitting.
Long story short, they swapped out my old battery in and told me that there was no fault as the heated windscreen was working again. Less than a week later, it wasn't again and they weren't interested in sorting it out.
I've never run start stop as that is hard on batteries and starters, and my journeys are long enough to recover the starting charge lost.
All in, I won't be buying a Ford again. 3 dealers, nil interest and a smart system that's pretty dumb.
I hope your battery system is working again. I'm back to old school ice scrapers again this year it seems!!!
There could be three reasons why the Alternator is kicking out 13.1V. the PCM com or monitor line is damaged so the PCM cannot tell what the Alt is producing, or to produce more if needed. 2. The PCM battery monitoring circuit is fried (unlikely), or finally and most likely, 3. The smart part of the alternator isn't listening to the PCM's instructions so defaults the output to 13.1V so it does t damage the battery.
To diagnose completely, you'd need to hook a multiline digital volt meter up to all the relevant signal lines & the + & - lines and monitor the signals on a Laptop with the engine running. This will show if the PCM is talking to the Alternator and what the response is from the Alt. If it is talking but there is no change in charge output, then the alternator is goosed.
If there isn't a signal from the PCM, check the harness is good and if it is......I don't know enough to say it but it could be a new PCM.
My 2017 2.0TDi SMax's heated windscreen has worked about 5 times since I owned the car. Last Xmas, Ford had my car on 5 occasions (3 different dealers). 2 days & nights at one and they still couldn't get their fault machine to diagnose the car as that is impossible if the battery charge "isn't above 75%." So, I took my car home, charged the battery fully and drove it back to the dealership on the 3rd day.
Their battery tester confirmed the battery was above 95% charge, the car only saw 64% charge. So, the dealership charged it overnight (they didn't believe me it seems) and found the car only saw 69% charge the following morning.
That was 14hr+ of charge after I had charged it at least 16hrs at home. Ford emailed Ford Germany (the SMAX Boffins apparently) and were told it's a common fault with that engine SMax and 1 version of Transit vans. Their response, charge the car with the ignition on but not running. Sure enough, on the 4th day after another night of charging, the car showed 78% charge and showed no faults.
The heated windscreen also worked again so "no fault found" was Ford's response. My reply was that their clearly was a fault as the cars SMART battery system should be able to see a fully charged battery if there is one. So, after much hassle, Ford Germany said to change the battery (as a trial only) and tell the PCM that the battery had been changed. This should give a default battery charge % of 85% to enable all systems and diagnosis if there were other faults........low and behold......it didn't. The system showed a charge less than 70% even though the dealer had charged the new battery to max prior to fitting.
Long story short, they swapped out my old battery in and told me that there was no fault as the heated windscreen was working again. Less than a week later, it wasn't again and they weren't interested in sorting it out.
I've never run start stop as that is hard on batteries and starters, and my journeys are long enough to recover the starting charge lost.
All in, I won't be buying a Ford again. 3 dealers, nil interest and a smart system that's pretty dumb.
I hope your battery system is working again. I'm back to old school ice scrapers again this year it seems!!!
Edited by Blahde2 on Thursday 17th October 22:32
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