R53 won't start - battery appears fine, absolutely nothing when key turned

[GeeJay]

Hi All,

I was wondering if anyone could shed any light on my situation before I spend a few quid on the incorrect item.

About a week ago, and this was a one off - the car didn't start when I turned the key. Everything seemed normal; the fuel pump primed, the dash lights came on and subsequently off again, but turn the key to the cranking position and I had a single turn, like the starter firing once, but no crank. I've had a few flat batteries in my time, but this wasn't the same symptoms. Anyway, it had been fine ever since until a really cold night when it did this 3-4 times and then finally gave up and nothing happened after turning the key to firing.

The next morning, I set the car in gear with the ignition on and rocked it back and forth a few times, then it started absolutely fine.

Today it's totally died and nothing I can do will get it to even fire/turn over. The fuel pump primes just fine, and the dash lights up as ever, along with the lights functioning so I am sure it's not the battery/a fuelling issue.

I have checked the terminals on the battery and they are all tight and clean.

Any idea where to look next? I suspect it's the starter motor itself but haven't seen a definitive solution that matches my symptoms. Others have mentioned a new immobiliser box and key reprogram, but surely that would mean I'd never get it started, not just 3-4th time?

Any help would be greatly appreciated.

[rieste]

Have you checked the connections on the starter motor? Maybe the main power lead or the earth lead.is not tight enough,

[GeeJay]

I haven't had the chance yet, but will hopefully tomorrow - just wanted to check some suggestions here before investing in a new one. Thanks!

[techlab2k]

Hi, this is a total shot in the dark as I haven't looked at the Mini barrel but I had a similar issue with a BMW 3 series a while ago. The key barrel was connected to the wiring with a nylon rotary switch. The fault was the nylon switch deforming and not turning. This gave the impression the key was turning all the way but the nylon switch only turned to key position two before it deformed. Take the shroud off the column and see if the barrel connects to a similar switch? The fault cost me over £900 to find and was repaired by a £15 part. The good news was that BM refunded all my outlay and let me keep all the new parts. Hope this helps. Good luck.

[GeeJay]

Wow, thanks techlab! Definitely a starter for ten, thanks. I had read on one search something about the barrel so will look there

[mab01uk]

How old is the battery?
Modern batteries often fail in the way you described, especially at this time of year. Mine did this on Sunday, dash lights but no starter or one turn, I was however expecting it to happen as the battery was the original 2002 BMW item........replaced it with a new battery from Halfords and all is now fine.

[GeeJay]

Alrighty - it's been a cold evening out there, with the exception of bump starting it to get it home. Here's the diagnostics so far:

Battery I am pretty confident is fine. It's got a June 2008 sticker on it, and is a BMW part.
Battery tests at 12.8v.
Car will not start even with jump leads connected to another running car, nothing what so ever.
Battery +ve terminal in the engine bay reads 12.8v too, so there doesn't appear to be a voltage drop there.
I also put the battery on charge for a good 4 hours and this made no change to the output voltage or starting.
Lights on drops the voltage around 0.5v
***Interesting point*** turning the key past position 2 (ie. to start) has absolutely no effect on battery voltage - is this expected?

That's the main diagnostics for this evening, albeit trying to locate/see the SM from above.

Also, for reference after a while of trying with some assistance, we did get it to start with a push. However upon arriving home (10-15minute, 3 mile drive) i tried starting it again and had the exact same symptoms - nothing.

So thanks for the ideas so far everyone, and if anyone has any more comments or opinions on the above they will be greatly received.

Tomorrow is going to be getting the car in the air and checking connections to the starter visually and cleaning them, then checking the voltages across the permanent 12v, earth and ignition 12v to eliminate ignition issues.

Failing that, it'll have to be a bench test on the SM.

I'll keep this post fully updated for future users and open to opinions.

Thanks for all the input!

[XRV848]

The first Law that you learn in electrical engineering is Ohms law which basically states that for every amp of current flowing through a resistance you will develop one Volt across that resistance. If you are measuring the voltage in the engine bay, then a 0.5V drop with the lights on is to be expected as the cabling and connections between the battery and the engine bay will have a small resistance (there is also resistance within the battery, so the terminal voltage will also be lower under load).
What is of concern is that with the starter engaged (key in position 2) there is no volt drop. This indicates that no current is being drawn by the starter. This is probably a fault in the low current part of the circuit through the switch to the starter solenoid, although it could be the starter itself if the low current starter circuit is not common with the circuit to the point where you are measuring the voltage. Techlab’s suggestion of a fault in the starter switch is a strong possibility, as is a bad connection anywhere in that circuit (this also includes the immobilizer circuit) or within the starter solenoid. Here in Canada, we also have a clutch operated interlock switch, but I don’t think you have that in the UK.
Check the connection at the solenoid (mounted on the starter motor, the smaller connection, probably a black/yellow wire). There should be a voltage here with the ignition switch in the start position 2. If a voltage is present, then the fault is either in the solenoid or in the starter motor. If not, then you will need to trace the wiring from the ignition switch to the solenoid to see where the voltage disappears (black/blue wiring from the ignition switch to the immobilizer, black/yellow wire from the immobilizer to the solenoid).

[GeeJay]

Thanks XRV848 for your post, it was very helpful today, and below are my findings:

After spending a good while giving a visual inspection under the car, everything seemed okay, no cables hanging or worn or loose.

About the only other progress was this:

Permanent live was reading a steady 12+ volts.
The ignition however only showed 0.06v when the key was turned - so does anyone have an explanation to that? If it was 0 then I'd suspect a dodgy ignition barrel, but as it ticks to 0.6 for as long as the key is turned and back to 0 when the key is released, what could this be? A short somewhere between the ignition and the starter?

Would it be safe to 'trick' it into starting by popping a screwdriver between the permanent 12v terminal and the ignition terminal to test the starter?

Can someone confirm that my idea of terminals is correct:

Red = Permanent live
Yellow = Ignition
Blue = Ground

h**p://i622.photobucket.com/albums/tt304/GeeJay86/ministarter.png

[XRV848]

The small voltage on the yellow terminal could still indicate a faulty ignition switch or bad connection somewhere in the wiring. The yellow connection is the starter solenoid, which is an electromagnet that engages the starter gear with the flywheel and then switches the high current (from the red terminal) to the starter motor.
The low voltage measured at the solenoid terminal could also indicate a fault in the solenoid causing a low resistance circuit to ground, but this is unlikely as the fuse in this circuit would have blown. The reason I’ve identified that possibility is that using a screwdriver to connect the starter terminal and the solenoid terminal (red to yellow) should result in the starter operating (albeit with lots of sparking!) as the solenoid now receives current from the red terminal. However, if there is a short circuit in the solenoid then, as the motor connection is to all intents and purposes unfused, you could end up with the equivalent of shorting the battery positive to ground.
I would first try disconnecting the solenoid connection and then measuring the voltage on the disconnected wire (make sure that the wire keeps clear of any grounded metalwork). This may show that there is no voltage with the switch in the start position and confirm that there is a problem with that circuit, but with the solenoid disconnected, there will be no current flowing (except the small amount through the meter) and the voltage drop across any bad connection will be less.
If you want to try a direct connection to the solenoid, then take the supply from a fused circuit (a 20A circuit should be adequate). Remember, there may be sparks and heat so be safe and adopt the appropriate protection. Also, the electronics in the car may not like the sparking and other effects of connecting the highly inductive solenoid, so try and choose a motor circuit instead of an electronic box circuit, or, better still, run an inline fuse from the battery terminal in the engine bay.

[GeeJay]

Quote: Originally Posted by XRV848 (original)

The small voltage on the yellow terminal could still indicate a faulty ignition switch or bad connection somewhere in the wiring. The yellow connection is the starter solenoid, which is an electromagnet that engages the starter gear with the flywheel and then switches the high current (from the red terminal) to the starter motor.
The low voltage measured at the solenoid terminal could also indicate a fault in the solenoid causing a low resistance circuit to ground, but this is unlikely as the fuse in this circuit would have blown. The reason I’ve identified that possibility is that using a screwdriver to connect the starter terminal and the solenoid terminal (red to yellow) should result in the starter operating (albeit with lots of sparking!) as the solenoid now receives current from the red terminal. However, if there is a short circuit in the solenoid then, as the motor connection is to all intents and purposes unfused, you could end up with the equivalent of shorting the battery positive to ground.
I would first try disconnecting the solenoid connection and then measuring the voltage on the disconnected wire (make sure that the wire keeps clear of any grounded metalwork). This may show that there is no voltage with the switch in the start position and confirm that there is a problem with that circuit, but with the solenoid disconnected, there will be no current flowing (except the small amount through the meter) and the voltage drop across any bad connection will be less.
If you want to try a direct connection to the solenoid, then take the supply from a fused circuit (a 20A circuit should be adequate). Remember, there may be sparks and heat so be safe and adopt the appropriate protection. Also, the electronics in the car may not like the sparking and other effects of connecting the highly inductive solenoid, so try and choose a motor circuit instead of an electronic box circuit, or, better still, run an inline fuse from the battery terminal in the engine bay.

Hi there,

Thanks again for this info. I have just taken your advice and taken the ignition wire from the starter motor and tested the voltage on crank - 11.6v.

So is this indicative of a faulty SM solenoid?

Thanks

[XRV848]

No, I would guess that it's a bad connection somewhere within the ignition switch, the immobiliser or the wiring for that circuit. The fact that the voltage is 11.6V instead of the expected 12-13V indicates that there is some voltage drop caused by the small current drawn by the meter (remember Ohms law!). There is obviously a lot of guesswork here, but what I'd now do is trace the wiring from the solenoid connection to the switch and find where in the circuit the voltage drop occurring. As a first step, I'd measure the voltage at the ignition switch connector and see if it is a faulty switch.

[GeeJay]

Quote: Originally Posted by mab01uk (original)

How old is the battery?
Modern batteries often fail in the way you described, especially at this time of year. Mine did this on Sunday, dash lights but no starter or one turn, I was however expecting it to happen as the battery was the original 2002 BMW item........replaced it with a new battery from Halfords and all is now fine.

Thanks for your comments - the battery is a little over 3 years old so I took it to the local ATS to have it load tested for good measure - comes back as absolutely fine.

[techlab2k]

Does it push start first time every time? Do the dash lights go out or dim when you turn the key?

Try 'hot wire start' with the key in. This is so like my BM problem now it's spooky.

[GeeJay]

Quote: Originally Posted by techlab2k (original)

Does it push start first time every time? Do the dash lights go out or dim when you turn the key?

Try 'hot wire start' with the key in. This is so like my BM problem now it's spooky.

Can you provide more details of hot wire starting please?

Edit: Nothing dims or goes out when key is turned, push starts every time yes

ps: Is this the nylon piece you are talking about?

h**p://***.ebay.co.uk/itm/BMW-MINI-COOPER-IGNITION-SWITCH-2007-2076K-/330610728520?pt=UK_CarsParts_Vehicles_CarParts_SM& hash=item4cf9ef5e48#ht_5323wt_848