MG-Rover.org Forums banner

1 - 20 of 34 Posts

·
Registered
mg_tf
Joined
·
33 Posts
Discussion Starter #1
Hi All,

There's an awful lot of posts here on this subject and they have been very useful to me in trying sort out that very problem on the wife's LE 85th anniversary.

However, I've not read them all so please forgive me if I'm repeating something you all know about, but if you leave one of these bad boys plugged in, even with nothing in the USB end, it will drain your battery fairly rapidly. The device is a transformer so it has continuity from the center 'button' to the side thingies. And as the cigar lighter socket is permanently live, rather than switched through ignition or accessories, you have a recipe for a flat battery.

135896


Adam
 

·
Premium Member
Joined
·
499 Posts
Yes, my TF was switched so as the cigar lighter was dead until ignition on. i wired a dash-cam into the same circuit-I put a dc-dc converter in so as no wires showing and that also was switched. Worth putting a tong-tester across the positive to see if you have something high draining . The alternator seems a culprit but the LE500 had an alarm, so someone stated - and that will have a nicad which doesn't last forever - causing the battery to drain.
 

·
Registered
mg_tf
Joined
·
33 Posts
Discussion Starter #4
OK guys, you had me doubting my sanity so I checked again and the cigar lighter is permanently live on my wife's LE 85th model. Maybe this arrangement is only on the LE or 85th models though I cant imagine why the manufacturer would bother changing it. Maybe the previous owner re-wired it for some reason. Perhaps an LE owner could let me know if theirs is switched or not?

Another issue has become apparent, when locking the car, pressing the 'lock' button on the fob ONCE engages the 'Superlocking' exactly as described in the TF handbook, pressing the 'lock' button a second time does nothing in addition. I'm sure this has nothing whatsoever to do with the battery drain but it seems to indicate that the manufacturer was fiddling with things to the very end.

135906


The TF Handbook is the only handbook we have. Does anyone out there have a definitive list of the differences between TF / LE500 / LE 85th. ?

Adam
 

·
Registered
Joined
·
1,128 Posts
On the MGF one push of the fob is lock and two pushes of the fob is for super locking. Another difference.....

PS Apparently the Rover 75 mark 1 lighter had it switched and on the mark 2 it was live.
 

·
Registered
'10 TF135
Joined
·
336 Posts
silversloth I have a '10 reg 'Motors' TF135. I have just tried the cigar lighter and it lights up independently whatever the key switch position; off/accessories only/fully on. I can confirm that mine is permanently live.

(The cd/radio doesn't work in the 'off' posn but does on the other two.)

Having had both F and TFs I can also confirm that for the F remote one push locks the door and a second push double-locks/super-locks it, whereas one push of the TF button both locks and double-locks in one action. As you lock a TF with the remote you can hear lock 'clunk' followed by dead/super-lock 'second clunk' as two separate actions from one push of the remote button.

(If I remember correctly there seemed to be an inference that this was an 'improvement' to the TF that paid tribute to the insurance industry and enabled security from theft (of the car - not from it) if you locked the car with the hood down. Apparently...:oops:...)

I can also confirm that the noisy alarm on my 'chinese' TF135 still works when the car battery is disconnected and (embarrassingly on a Sun morning...) could only be turned off by a lock or unlock from the remote (too frantic to remember which) when I was playing about with the key trying to get some lube into the driver's door lock. (Previously seized - but that's another story...)

ps the physicist in me finds it hard to believe that there will be battery drain unless something is actually using up current, warming up or lighting up. ie Does your cigar lighter circuit get warm on its own? Or is there a bonnet/ boot bulb alight etc?

Hope this helps...I can't see why the 85th/500 models should have different electrics in this area tho'...
 

·
Registered
mg_tf
Joined
·
184 Posts
The cigar lighter in my 02 TF is also permanently live. I have replaced with a dual USB socket, this does have a built in light so is on permanently. Mine is on a battery conditioner when not used so no risk of draining the battery. On the occasions when I have not put it on the charger, the battery is still able to start the car after two weeks so the USB light drain in minimal.

As per ArntyR check boot light is turning off when you close boot lid. You may need to remove one of the back lights to see inside the boot with the lid closed or check to see if the boot lid bulb is hot as soon as you open the boot.
 

·
Registered
mg_tf
Joined
·
45 Posts
Easiest way to check the boot light is turning off is to use a mobile phone camera. Set it to video/record, place in boot and close the boot lid. Open and check the footage ..... simple
 

·
Registered
mg_tf
Joined
·
33 Posts
Discussion Starter #10
I would imagine that the changes to the wiring of the cigar lighter and door lock probably took place 'across the range' at a moment in time rather than being introduced on specific models. Or maybe with the introduction of the N series engine if other changes to the loom were also necessary.

The alarm 'siren' was inoperative and found to be very badly corroded internally so it's been removed from the car and the battery drain continues. The bonnet and boot light bulbs have both been removed and the battery drain continues.

The further I get into this problem the more my mind is focusing on the ECU relay pack. Going to get a more knowledgeable pal of mine engaged on the problem at some point.

Btw, AntonyM, nice trick with the mobile phone camera. Does your fridge light go out when the door is shut? :)

Adam
 

·
Registered
mg_tf
Joined
·
33 Posts
Discussion Starter #11
I would imagine that the changes to the wiring of the cigar lighter and door lock probably took place 'across the range' at a moment in time rather than being introduced on specific models. Or maybe with the introduction of the N series engine if other changes to the loom were also necessary.

The alarm 'siren' was inoperative and found to be very badly corroded internally so it's been removed from the car and the battery drain continues. The bonnet and boot light bulbs have both been removed and the battery drain continues.

The further I get into this problem the more my mind is focusing on the ECU relay pack. Going to get a more knowledgeable pal of mine engaged on the problem at some point.

Btw, AntonyM, nice trick with the mobile phone camera. Does your fridge light go out when the door is shut? :)

Adam
I would imagine that the changes to the wiring of the cigar lighter and door lock probably took place 'across the range' at a moment in time rather than being introduced on specific models. Or maybe with the introduction of the N series engine if other changes to the loom were also necessary.

The alarm 'siren' was inoperative and found to be very badly corroded internally so it's been removed from the car and the battery drain continues. The bonnet and boot light bulbs have both been removed and the battery drain continues.

The further I get into this problem the more my mind is focusing on the ECU relay pack. Going to get a more knowledgeable pal of mine engaged on the problem at some point.

Btw, AntonyM, nice trick with the mobile phone camera. Does your fridge light go out when the door is shut? :)

Adam
 

·
Registered
mg_tf
Joined
·
33 Posts
Discussion Starter #12
The car has had little use lately and we are living with the battery drain issue by keeping a spare battery charged up and jumping the car or swapping in the spare battery as and when required / appropriate.

My more knowledgeable pal has failed to materialize so as it’s been a bit sunny, dry and warmish on the Dorset coast today I did a bit more delving and have satisfied myself beyond doubt that the alternator is functioning correctly.

However, whilst checking that I had voltage at the 80amp fuse I found that I had 12.5 volts when I chose to put the negative test probe on a shiny component of the engine but only 7 volts when the negative probe was against the alloy body of the ECU. My curiosity was aroused and I connected a continuity meter from ECU body to other components both shiny and not shiny and the meter was showing a fair resistance wherever the probe was placed. Is this normal, or could it indicate a fault within the ECU?

Any guidance would be most welcome.

Adam
 

·
Registered
MG TF 135
Joined
·
14 Posts
Hi all,

For anyone that wishes to check their battery drain against maximum official values, this is what MGRover said in their Tech Tip No TT00361/5/2002

MG F, MG TF Ignition On with Engine Running 5.8 amps. Ignition Off 19 to 21milli-amps

To the original post. I have a SAIC MG TF with always live cigarette lighter. With a twin USB / indicator light it pulls an extra 9 milli-amps. It should only be the LED indicator pulling power if nothing is plugged in to it. With a tyre monitoring receiver plugged in it pulls an extra 0.5 amp. I don't worry about leaving the USB socket plugged in all the time, but pull the Tyre monitor out enough to disconnect at end of journey.

Cheers

Mark
 

·
Registered
mg_tf
Joined
·
414 Posts
Perhaps I’m not reading this correctly, but some months on, this car is still suffering from a parasitic drain of unknown origin, and to the extent that it results in being jump started or batteries changed.
I guess it’s OK to live with this - indefinitely? If there is good intention to sort it rather than put up with it, then the correct procedure is to remove each fuse in turn until the offending circuit is identified- at which stage it becomes necessary to fault find that particular circuit.
To me, it seems illogical to simply jump upon one circuit and investigate this, when it’s not known whether this is actually the offending circuit or not.
Re acceptable drains:- my rule of thumb has been c50mA max is reasonably acceptable, with the vehicle locked up and the system having ‘gone to sleep’.
 

·
Registered
Joined
·
1,128 Posts
I am in the process of 1. Full recharge 2.Pulling one fuse 3. Seeing how long it takes before the battery is in need of a recharge (using CTEK traffic light battery indicator). So far not found the cause of the rapid discharge; the battery is in need of a recharge once a week.
 

·
Registered
'06 MG ZR +120 (HQM) '04 MG ZR 105 (IAB)
Joined
·
9,366 Posts
Another issue has become apparent, when locking the car, pressing the 'lock' button on the fob ONCE engages the 'Superlocking' exactly as described in the TF handbook, pressing the 'lock' button a second time does nothing in addition. I'm sure this has nothing whatsoever to do with the battery drain but it seems to indicate that the manufacturer was fiddling with things to the very end.
I am not sure what the issue is here?

Prior to late 2003 changes to the security system, and where superlocking was fitted, you had to press the button twice in reasonably quick succession to engage the superlocking. On any TF (or 25/ZR, 45/ZS) built from late 2003 onwards, a single press of the lock button on the fob locks the car and engages the superlocking. A second press does nothing, because there is nothing else for it to do.

It was part of a series of revisions to the security system which took place in 2003 which lifted the Thatcham security rating of several of the MG Rover models to a higher grade (thereby reducing insurance groups). It culminated with the fitting of the Pektron SCU - this was the point at which substantial changes to the wiring system took place as the SCU took ove the control of several key electrical functions. This system continued to be used in the Chines TFs like your 85th.

Re. the Pektron SCU - if you are continuing to suffer from battery drain, I would caution against continuing to allow the car to stand with a draining battery. A gradually depleting battery has been pinpointed as a major cause of the SCU suffering 'memory loss' or corruption; not only sometimes losing the settings for various functions to work, but sometimes also corrupting the code which the SCU shares with the engine ECU to disarm the immobiliser (resulting in the car not being able to be started. Possibly better to disconnect the battery altogether until you have traced the parasitic drain.

The only real way to do so is (as Austin2297 has already said) to disconnect the battery earth lead and put a tester between the battery negative and the earth point and measure the current. Then disconnect each circuit one by one (remove each fuse in turn) and see which one causes the drain current to drop. You then have to delve deeper into that circuit to find the fault.

Favourites in the past have included the engine ECU not shutting down correctly, and the interior light circuit not closing off properly due to a faulty door switch.

There were some differences between the MG Rover TFs and the Chinese built ones, but I seem to think this was mainly due to differences in connectors used, rather than wholesale changes to the electrical system.
 

·
Registered
'10 TF135
Joined
·
336 Posts
Please, there's no attempt at thread hijack but...

"There were some differences between the MG Rover TFs and the Chinese built ones, but I seem to think this was mainly due to differences in connectors used, rather than wholesale changes to the electrical system"

...slightly bigger electrical changes than connectors used, Man in the Car, as I'm gradually encountering after (getting on for) 3 years of ownership:-

A different ecu - a different part number - claiming EU4 compliance.
Non MGR 'access code' couldn't unlock mine for repair (of checksum error...)
Different fuel injectors.
Oil service interval countdown continually 'in-yer-face'...only SAIC specific diagnostics can zero this.
Apparently 'weaker' SAIC ecu (according to a remapper...)
Inability to remap ecu conventionally through OBD port (or...perhaps, at all?)
No EKA code provision (driver door key alternative access only - prone to seizing due to lighter lock build(?) and lack of use! :oops:)
Ecu that has a propensity to slip into 'checksum error' - as far as I know as a result of attempted remap.
Most affected 'checksum' ecus seem to then experience a higher tick-over, hotter running and a very frequent engine fan (in my case I believe running continuously when warm) and staying on...(based on a limited sample size, though)
Apparent full Thatcham 1 alarm/immobiliser compliance - certainly the (now) independent alarm cannot be switched off by battery terminal disconnection.

...these despite the same scu control box (YWC001541(?))...

ps not nit-picking but hoping to 'spread the word' as someone who's continually making discovery after owning MGR F, TF then SAIC TF
 

·
Registered
1995 MGF Mpi
Joined
·
842 Posts
For anyone that wishes to check their battery drain against maximum official values, this is what MGRover said in their Tech Tip No TT00361/5/2002

MG F, MG TF Ignition On with Engine Running 5.8 amps. Ignition Off 19 to 21milli-amps
Hi Mark,

Do you by any chance of the pdf copy of the Tech Tip TT00361?

Mark
 

·
Registered
mg_tf
Joined
·
33 Posts
Discussion Starter #19
Thank you all, gentlemen;



Mark,

Interesting info from MGR Tech Tip, the car with fuse F5 removed is well within limit at 17mA.

We have three 12v to USB adaptors for various purposes and I only checked one of them previously. The other two are now checked and showing no continuity internally. As from next Tuesday we will only have two, once the bin men have been. Sorry for potentially misleading you.



Austin,

The car is, or was, my wife’s 16-mile e/w daily commute to work before lockdown started last year, since when she has been working from home so the car gets little use. The battery drain was first noticed about three weeks into lockdown. A return to the office might be announced any time soon so that has concentrated my mind to sort the problem.

Thank you for prompting a long overdue sanity check.

With bonnet up, bonnet switch disconnected, car shut but not locked there was a draw of 70mA

Withdrew fuses one by one, F5 was the only one to have any significant effect, draw reduced to 17mA

This led me to fuse 23 which when pulled had no effect on the draw, still 70mA

Conclusion, there is a fault within the central locking system. Never having had any involvement with C/L I’ll take a stroll through the posts on this forum for clues as to what to look for next.



Julian,

I would thoroughly recommend that you get your hands on a ‘cheap and cheerful’ multimeter so that you can go through the fuses in a logical manner and quickly identify the defective circuit without waiting a week between checking each one. (Please forgive me for sounding a bit like the Pot calling the kettle black).



Adam
 

·
Registered
mg_tf
Joined
·
1,596 Posts
Well I have to leave my TF unlocked otherwise the battery runs down in a few days, so that seems to validate the central locking fault theory. It's off road anyway so no big deal, but I'll try and measure my current draw when I get a chance.
 
1 - 20 of 34 Posts
Top