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59 Plate Fiesta 1.4 Battery Going Flat


ashley750
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Since I bought the car a couple of months ago (1.4 Titanium Auto, 27k, with keyless start), I have had the battery go flat on me 3 times. The battery is a Halfords HCB063. After the second time I popped into Halfords for a battery check. Guy said it looked like their most recent design and was probably only a year or so old, which tied in with the fitted sticker starting at 2016. The battery checked out fine, but showed it needed more charge. 

Flat again yesterday, so charged it up overnight and spent some time on it with the multimeter yesterday. Battery voltage was 12.57 V after charging, and 13.95V with the engine running, so looks like the alternator is charging OK. I then disconnected the earth battery cable, and measured the amps being pulled after the car was locked, and got 0.32A. This is high, as generally the draw should not be greater than 50mA (0.05A), as a comparison, our VW Polo was only pulling 0.01A. Started pulling fuses, and removing either fuse 16 (Powertrain control module, high and low cooling fan), 18 (Powertrain Control module) or 27 (PCM) dropped the drain to 0.09A. 

At this point I'm stuck, as none of the wiring diagrams in the Haynes manual show those fuses, or the PCM :angry-banghead:.

Can anyone help?

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Hi Bobr, 

Nothing plugged into the aux socket at all. Have left the multimeter on for 50 mins today, and it dropped from 0.32A to 0.24A, plenty of time for all the systems to shutdown, but still well above 0.5A.

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At bit more testing. With everything fully asleep, draw was 0.25A. I then pulled fuses:-

  • 16 (Powertrain control module, high and low cooling fan) - dropped to 0.02A
  • 18 (Powertrain Control module) - dropped to 0.02A
  • 27 (PCM) - dropped to 0.00A

Pulled all the other fuses in the engine and interor fuse boxes, none of which made any difference. Also checked the boot light and it turns off OK.

So could do with more info on the PCM - location, wiring etc.

Thanks.

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On my 2015 fiesta I found that the glovebox light was on all of the time. I never had problem with flat battery but noticed one day that the stuff at the top of the glovebox (I had quite a lot of stuff in there) was always hot and then realised it was the glovebox light . I have now removed the light, who needs it anyway. 

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18 hours ago, ashley750 said:

With everything fully asleep, draw was 0.25A. I then pulled fuses:-

  • 16 (Powertrain control module, high and low cooling fan) - dropped to 0.02A
  • 18 (Powertrain Control module) - dropped to 0.02A
  • 27 (PCM) - dropped to 0.00A

Replacing a faulty PCM would be a difficult and expensive job. But before that, bear in mind all the major modules are connected together by CAN buses. It is quite possible that the radio, or sat nav, or bluetooth adapter is staying awake, is keeping the buses active, and that activity is preventing the PCM, and maybe the Instrument cluster and BCM from powering down properly.

The PCM does pull a high current when it remains active.

Check if any backlights (eg on the trip meter) on the cluster stay on permanently. They should go off after 10 to 30 minutes of being left idle. That is often a symptom of unwanted bus activity. And it is the add-on gizmos that are most often the culprits in this.

There is a drawing of a typical Fiesta PCM & engine wiring I have found, but it is hard to follow from the way it has been chopped up. I am not sure it will help much.

fi08-pcm.pdf

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Is there a PCM relay? If so it might be worth checking that works properly, in particular that it opens and is not stuck in the closed position.

It may also be worthwhile plugging an OBD adapter (one that supports high and medium speed in order to access all busses) and seeing if Forscan can pick up any fault codes.

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Took it to a local garage last night. Very helpful guy hooked up his battery tester and it kept coming up with battery unstable. So will order a new battery as a starting point. Hoping to be able to fit a 077/012 battery if the strap can accommodate the extra 15mm, gives me a few more Ah over the 063. Will probably go for a Varta Silver Dynamic - reasonably priced on Tayna.

He also pointed out the alternator looked like it had been replaced previously. How do I check the smart charge alternator?

I did notice a battery saver relay in the fusebox behind the glove box, so will check that out. Also sat in the car and locked it, everything seemed to switch off OK - only lights were a orange one on the interior locking switch, and a flashing red one in the centre of the instrument panel.

 

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Be wary of mixing up cause and effect here - the battery might be dead because it has been deep discharged due to the constant high parasitic load that you've measured.

If the battery is defective, might Halfords honour the warranty on it if it can be proven (without a receipt) that it was indeed only purchased/fitted last year? I wouldn't mention that you are not the original owner as from a moral perspective I don't think it is relevant.

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23 minutes ago, ashley750 said:

How do I check the smart charge alternator?

A good way to test an alternator over all driving conditions, is to use a cigar lighter / power point plug-in voltmeter, just a couple of quid off Ebay. Then you can see the voltage while driving, hot & cold engine, day time light load, night time heavy load, etc.

These things can be a bit inaccurate, and there will be some voltage drops in the wiring, so it is a good idea to do some comparative tests on the driveway, with a multimeter on the battery terminals, to get a feel for any deviations.

Then you should expect it to hold at 14v to 14.5v most of the time while driving. Very heavy loads like de-misters may get it down below 14v, but normal loads (headlamps, vent. fan, wipers) should be ok, even at idle speed.

When the engine is hot, it may also drop a little, but I would say still over 13.5v, this would be the "smart charge".

The voltmeter can also give a rough indication of unwanted drain. If the battery gets pulled below about 12.2v after sitting for a couple of hours, suspect a drain on it.

Like Matthew (MJNewton) says, repeated deep discharge may have worn out the current battery prematurely. That 0.25A load you measured would take 6AH of charge per day out of a battery, and they are not really designed for that.

 

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On 8/7/2017 at 11:35 PM, Tdci-Peter said:

There is a drawing of a typical Fiesta PCM & engine wiring I have found, but it is hard to follow from the way it has been chopped up. I am not sure it will help much.

fi08-pcm.pdf

Thanks for the wiring info, it ties in with what is shown in the Haynes manual. There looks to be a PCM relay in the engine bay fusebox (R8), so will check it works OK. Fuses 16 and 17 are switched by the relay, so odd that there is a draw through them when you would expect the relay to be open. 

Have ordered a Bosch S5 battery, so will see what happens when that is fitted.

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24 minutes ago, ashley750 said:

There looks to be a PCM relay in the engine bay fusebox (R8), so will check it works OK.

The PCM relay is controlled by the PCM. It enables the PCM to perform post-ignition off tests and any other jobs, like keeping the fan running if hot, then it should turn the relay off when finished, to fully power itself & related equipment down. If the relay was jammed on (with coil de-energised), that could cause a power drain.

But if it is the PCM holding the relay on, it would be much harder to diagnose. It could be a faulty output circuit in the PCM (unlikely, I think), or just that the PCM is not being allowed to go to full power down, for some reason.

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So the PCM relay has checked out OK, and I measured the voltage drop across the fuses, getting

  • 16 (Powertrain control module, high and low cooling fan) - 0.2mV
  • 18 (Powertrain Control module) - 0.5mV
  • 27 (PCM) - 2.4mV
  • all other fuses were at zero.

So something is going on with the PCM. Measured across the battery and only just over 10V today. Time to mention the "The Consumer Rights Act 2015" to the place I bought it from :angry:.

I know bad earths can do wierd things, does anyone know where the PCM is earthed? The diagrams that Tdci-Peter posted refer to Shock Tower Left Bracket 1 Ground, but no idea where exactly this is. 

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2 hours ago, ashley750 said:

the PCM relay has checked out OK

Were you able to tell when and if the PCM relay was de-energising? If the voltage drops over F16 & F18 are valid, then it suggests the PCM relay was staying on, as I think it supplies power to F16, F17, and maybe to F18.

The shock tower will be the front suspension housing tower. But there are probably quite a lot of earth connections to this.

In a situation like this, I would probably resort to fitting a manual switch in the cabin, maybe hooking in to the F27 terminals in the fuse box, and re-siting the fuse in the line to the switch. That might keep the car going, and stop wrecking batteries, while finding the underlying fault.

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I was thinking similar regarding a manual cutoff switch for the PCM relay, perhaps making it permanent (and automatic) with a relay controlled by the battery saver relay if need be. It's not a proper fix but you may never get to the bottom of it. 

I can't remember if you've already said but have you performed a full code scan? 

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A manual switch is an interesting idea, but as I have only had it 2 months, I do not want to mess with the wiring, and I want it sorted by the dealer / warranty. I did scan the codes a while ago, and nothing came up, but will check again later. I might also remove the cover on the relay, so I can see what it is doing when in the car, I only checked it on the bench.

Went for the Fiesta due to the light steering, as my wife does not have full use of her left arm, but she refuses to use it as she is not confident it will start if she goes out in it. Really not feeling any love for this car at the moment :sad:.

 

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5 hours ago, ashley750 said:

but as I have only had it 2 months, I do not want to mess with the wiring, and I want it sorted by the dealer / warranty.

Understood. I had forgotten about or not properly read the first line of your first post!

For smallish battery drains, a solar charger unit could help, at least in the summer. But a 0.25A drain would need a big panel.

Unfortunately, this sort of long term, hidden problem can be hard for dealers to find & fix. So I see the need to investigate it first, but without invalidating any warranty. A lot of second hand car dealers (and some main Ford dealers!) would not have a clue where to start.

See if you can start by finding out just when that relay is being turned on & off. I still suspect the radio, or similar add-ons, or the wiring to them, might be the underlying cause. If it is the PCM, it is going to need some quite convincing evidence to get a dealer to change that. They are usually held in by security bolts that have to be drilled out, so you can not even get a good look at it or its connectors, without doing visible damage.

 

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To add to what Peter has said, I dare say - with some regret - that you sound like you've got probably got a much better ability for analytical assessment than probably all the dealers I've ever dealt with and so they may genuinely struggle to determine the cause of the problem leaving very little options for what they can do to remedy it. I hope to be proven wrong though given that, as you say (and as I too didn't remember!), you've only had the car a couple of months and so it really shouldn't be your problem to solve.

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Removed the cover on the relay to see what it was doing, and it was open with the car asleep, so relay is fine. I also measured the voltage drop across the PCM fuses with the realy out, and they remained the same, so an issue with the PCM relay is ruled out.

Bosch S5 battery went in today, old one was on less than 3V when I took it out. Will keep an eye on the voltage over the weekend, and disconnect if it looks to be pulling the battery down.

I also checked the draw on my Saab 9-5 1.9 TiD, that started of at 130mA, and then dropped down to 10mA.

Car is going into Carwood in Coventry on Wednesday, they seem to have a good reputation for electrical diagnostics. Fingers crossed.

 

 

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Monitoring the charge on the new battery, without using the car at all.

  • 12/08 10:45 - 12.67V (as fitted after being fully charged)
  • 12/08 19:55 - 12.51V
  • 13/08 09:39 - 12.34V
  • 13/08/17:33 - 12.21V

Car did start with 12.21V, but will disconnect the battery to prevent any further discharge.

 

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2 hours ago, ashley750 said:

Car did start with 12.21V, but will disconnect the battery to prevent any further discharge.

I think you did right there. battery voltages do change slowly with time, slowly dropping after being charged, or slowly recovering after a bit of discharge, but those voltages suggest it is being discharged, reinforced by the previous current measurements.

On my car, I can see that items like the EGR and MAP sensor are powered up for about 15 - 30 seconds after ignition off, then they all power down, and I assume that is when the PCM engine management relay goes off.

On your car, the PCM relay also seems to be turning off, but a PCM related drain is still being measured. I am still hesitant to blame the PCM for this. Partly because PCM faults are quite rare, and partly because it is expensive! Usually the only way to pin down a fault to the PCM is to carefully eliminate all other causes.

On the Fiesta '08 drawing, like on the Focus, the MS CAN bus goes from the BCM, via Audio modules and all other body related stuff, to the Instrument Cluster. The HS CAN bus goes from the Cluster to the PCM via all the under bonnet stuff. That is why I asked about the Cluster Odometer backlight earlier. It may be worth removing Cluster fuses, or disconnecting a connector carrying one of these buses, if you can locate it, to eliminate bus activity from the list of causes. C11 and C12 may carry the HS CAN bus, though I do not know where they are, or what else they carry.

Or see what Carwood say on Wednesday, keeping the battery charged until then.

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very interesting problem and i hope you get it sorted.

I had a 55 plate fiesta that was killing batteries to the extent that when the RAC came out to me after it wouldn't start they fitted me a fully charged new battery that lasted around 10 minutes before it cut out again!!

 

The fault turned out to be an internal short in the alternator, so we ended up disconnecting the main lead from it, and just driving home on another fresh battery, using the least amount of power possible!.

it might be worth disconnecting various electrical things to see if that lowers the power drain.

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So took the car into Carwood yesterday. They did a quick check, and have confirmed that the battery is being drained, and that the PCM appears to be the cause of it. However, they would need it for a day or two to delve further into the cause.

They also mentioned a buzzing noise from behind the dash. I had heard this and assumed it was supposed to do it, but the guy there said he has never heard it in a Fiesta before. I have put a recording on YouTube here. Should it do this?

Also noticed a spare connector under the dash, hanging by the steering column see picture. Two wires, one purple with red, the other green - any idea what it is, and if it should be connected to anything?

I have now written to the dealer I bought the car off, and have given him 3 options, all at his expense:-

  • Carwood have the car for further investigation of the electrical issues. If they are able to fix them, then they do so, although it would leave the ticking noise outstanding. If they found the PCM is at fault, then the car would still need to go to a Ford retailer for replacement.
  • The car is taken to my local Ford retailer to have all faults remedied.
  • The car is returned (less the items I have added) and a full refund is made to myself.

Will be interesting to see what response I get back!

 

 

P1050688.JPG

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So the end to this story is that the car went back to the retailer today, and I got a full refund. We are glad to see the back of it, but we now have to find a replacement, and this experience means it is highly unlikely to be another Fiesta.

To those that replied to my posts, thanks for your help and support. 

 

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