Jump to content
Do Not Sell My Personal Information


Focus Mk3 Location of Stop Start/Voltage DC/DC Converter Module.


DISC130
 Share

Recommended Posts

This unit is showing a current drain on the battery when ignition is switched off. I need to replace it,the Haynes manual doesnt show its location ,can anyone help please. Also will the module need paired to the ECU. Thanks in anticipation DISC130

Link to comment
Share on other sites


Hi David, happy to try and help you but there seems a bit confusion of what you  are needing to replace.

Start/Stop is a system which involves many modules and is unlikely to be causing a battery drain when the car is off.

Your car may well have a DC to DC converter for USB sockets (12V to 5V), but they don't use any power when off.

Do you have any fault codes - DTC's. What sort of current drain are we talking about ?

Link to comment
Share on other sites

Thanks for a quick reply. The drain appears to be intermitant, .5 amp read on the ground battery return when switched off (not always can be 10mA which is perfect.). No fault codes are showing.(Could just be not registering them)

This drops when removing F11 (Haynes mark it as the dc/dc converter, which I thought was the stop start module.) Coupled with this the stop start dosnt function any more. I am not qualified in any way and not the sharpest tool in the box. Just tested all the under bonnet fuses/relays first and F11 was the only one I found. Its one of those problems ,an auto electrician has looked at it and couldnt find anything.

The car has just done 15000 ,the battery has just been replaced and it still drains in a week. Alternater working fine.

Im on plan B now ,carrying decent lion jump pack.

Link to comment
Share on other sites

Hi David, lets deal with one problem at a time 👍

Stop/Start not working. Forget about it and just accept it for what it is, a very flawed system that never works as it should. There are well over 20 conditions that have to be "Just Right" for it to work. So don't waste time effort or money trying to resolve the issue - you won't !!  The very best you could hope for is getting it to work for a few weeks before once again it will break.

After the new battery was fitted did anyone do the reset of the battery Monitor ? If not then it needs to be done now, and even if it was done then there is no harm in doing it again. ( just ask if you need instructions of how to do it )

The normal drain current on your battery can be anything up to 80mA. You can only check this after the car has been parked up and locked for more than 30 mins otherwise you will get false readings as many on board modules can take 20 minutes to enter sleep mode when parked. Also do not have the key in your pocket (if you have keyless entry) or the car will detect the key and start to wake up.

With reference to the DC/DC converter I'm not sure what Haynes are refering to. I can only assume they are thinking of the 12V to 5V converter for the USB sockets but they would be switched off when the car is parked. Can you give anymore information on this ?

What is the battery terminal voltage after the car has been parked for 30 minutes and what is the voltage after standing overnight ?

Link to comment
Share on other sites

DC/DC converter is a different term to voltage regulator. The charging system/battery is designed to operate at higher voltages than conventional . Can have up to 15.2 v on occasions. That would play havoc with delicate electronics in today's cars so a DC/DC converter is used to regulate the voltages to a safe reliable lower voltage. 

The position is pretty much under the headlight switch. 

Link to comment
Share on other sites


1 hour ago, iantt said:

DC/DC converter is a different term to voltage regulator

Hi Ian thanks for that update. I'd not considered the fact that they were calling it by the wrong name.

The operation of a 'Voltage Regulator' is in fact totally different from that of a DC to DC converter, but given the term was quoted from a Haynes workshop manual it would explain the problem.

So now back to the OP's original issue of high current drain, it is very unlikely that the voltage regulator is the actual fault, far more likely that it is something that is drawing power via the regulator. The big issue there is that there will be a whole load of potential equipment that will be getting power from the voltage regulator, so its going to be very difficult to isolate individual items.

Link to comment
Share on other sites

UNOFIX and IAN-Educational and helpful replies many thanks I will supply all data requested in next two days. The Ford/ Varta EFB75A/h 700A Capacity was replaced in March 21 with an Exide efb75A/h 730CCA battery. The battery monitor wasnt reset,again cant find how to do it Haynes manual. Your input would be appreciated thanks.

The Stop Start module I bought was a Bosch BV6T-14B526-BC again the Haynes manual refers to it as Low Voltage DC/DC Converter,however I had read USA information that refers to it as a Stop/Start Module. Replacing it is now on hold with the advice given so far. All refer to same 30amp fuse F11. On checking the Haynes wiring diagram there are cabin fuses F78 F85 and boot R3 Relay linked to this complex circuit.

You have given me confidence that this problem is resolvable Thank you for that

Link to comment
Share on other sites

How to reset the battery Monitor Sensor (BMS) there are two different methods depending on the age of the car but I think this YouTube video is correct for yours.

When he talks about pushing buttons it is not pressing on/off it is just simply 5 presses of rear fog switch and 3 presses of hazard switch (yes the hazard lights will be left switched on) then wait for 5 seconds and you should see the battery light flash 3 times. - Let me know how you get on.

 

Link to comment
Share on other sites

Without seeing the circuit diagram it maybe that Fuse F11 is the supply to other fuses like Fuse F78 and F85, also the supply to relay R3 in the boot.

Since you know that removing F11 stops the current draw, I would now move on to try and narrow it down to either of the other 2 fuses or in fact remove relay R3 and see if any of them stop the current draw.

Side note: I would stay away from reading USA information, there 'terminologies' can be misleading and also there systems while similar they can have important differences.

Link to comment
Share on other sites

 5pm 21/7 Reset BMS last night first job ,battery light bleeped three times.

All readings double checked with two meters.

6pm 21/7 Checked voltages afterwards- battery 12.39v (Low) 60% Power- After 5 days use from full charge. 

A surprise to me was the reading with engine running 12.89v ,even when revved up. (Alternator not fully functioning)

10 am 22/7 Checked voltage -Battery 12.25v (Low) 42% Power -Engine wouldnt turn over.

Jump start (Noco GB40 jump pack) Then 7 mile trip with one normal start up.   Running Voltage check 13.96v ( Altnernator OK)

11pm 22/7 check 12.85v and 13.53v running. Surprisingly battery now show 100% ok

Needs tested over next few days ,there is a possibility the BMS battery reset may have worked. Alternatively there may just be an intermitant Alternator problem.

Worth mentioning just did another leak test with 30 minute delay to charge capacitors and no leak ,reading  0.001 amp 10 milliamps.

Also did a engine code scan ,no faults and no codes just now.

Sincerest thanks for your input so far and any further comment. Regards David

Link to comment
Share on other sites

Hi David, fingers crossed all is sorted.

Your car has an inteligent charging system and the alternator checks on the vehicle demand and what it thinks the battery needs. If the BMS had not been reset after the new battery was fitted then the alternator would in fact not be giving the battery the charging voltage required.

1 hour ago, DISC130 said:

the reading with engine running 12.89v ,even when revved up. (Alternator not fully functioning)

Agreed alternator is just suppying enough to run the vehicle but not enough to charge the battery (it thinks the battery is already charged).

1 hour ago, DISC130 said:

 Running Voltage check 13.96v ( Altnernator OK)

Thats more like it 😀 👍

Link to comment
Share on other sites

Well I  cant believe it was that simple. Thanks a  lot I have a long stay park coming up at Manchester Airport so that a relief. Keep intermitantly checking battery condition just in case. I cant thank you enough I m very grateful. David.

Link to comment
Share on other sites

Just to complete this thread the overall problem transpired today 24/7/21 when I took the 3 month old EXIDE battery off the car.

The charge lasted only two day then wouldnt start but all the readings on the battery were fine apart from a sky high milli ohm reading.(battery internal resistance)

The battery was cracked and acid was leaking out. Put a new Halfords battery on and reset BMS everything works fine including stop/start.

I think that old battery was a fake with an EXIDE label on it, another fight looming with the supplier.

Thanks once again for your help in trying to sort my problem out.

 

  • Thanks 1
Link to comment
Share on other sites

1 hour ago, DISC130 said:

battery was a fake with an EXIDE label on it, another fight looming with the supplier

Any problem with the supplier just contact EXIDE direct and tell them you think you may have been supplied a counterfeit battery. They will be keen to find the supplier !!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share




×
×
  • Create New...

Forums


News


Membership