Hey all,

 

The ignition switch in my 6N1 Polo...

 

I can turn the ignition on all the way, and everything turns on fine, except when I turn it a little further to start the car - nothing happens. Nothing at all, no clicking, no starter motor trying, nothing. Checked VCDS and it shows that the key is authorised (key authorised = 1) so it's not an immobilizer thing (usually the engine turns over but won't start with immobilizer problems though, right?)

 

Coming out the back of the ignition switch connector there's a Red wire and a Red/Black wire, if I manually touch these together the starter motor turns over fine, and the car starts fine if I do this with the key in and ignition on. Looking in Haynes these are connected to the correct places (it identifies them as Red to pin 30, Red/Black to pin 50) yet nothing when I turn the key.

 

This made me think ignition switch had gone. I needed to replace the steering column anyway due to some play and a strange sounding clonk from the UJ, so I got a good condition used column including switch and key from eBay and fitted it, assuming it would work fine. But connected everything back up, and I get exactly the same behavior!

 

What are the chances that this replacement ignition switch is failed in exactly the same way as the old one?! Makes me think there's something else wrong.... but I can't figure out what! Help?

 

Thanks in advance!

If touching the "50" wire to the "30" the starter engages, that rules out the wiring

4 hours ago, nige8021 said:

If touching the "50" wire to the "30" the starter engages, that rules out the wiring

 

That's what I was thinking.. but wasn't sure if I was going crazy or not. I guess it could just be coincidence that I have two ignitions with exactly the same problem, but before I try a third I wanted to check if there was any other possibility!

 

Does the ignition switch need a connection/signal from any of the other wires before it will actually bridge 50 to 30, if that makes sense, or am I overthinking it?

No the 30 supply is just switched to the 50 contact and spins up the starter motor.

Firstly, you are wrong about immobiliser faults.

If (for example) you try to start the engine with an 'unchipped' key, the engine would start, but then would stop again within a second or two.

I am assuming that your 'new' column came with its ignition key? Hopefully, the immobilizer box as well.

Did you change the immobilizer box ?

If the key ISN'T matched to the immobiliser, then you are likely to get the results that I have described above.

 

If you have a multimeter, you can check the VOLT-DROP over a switch/relay contacts, or indeed the complete circuit by connecting the voltmeter to both switch terminals with the switch in its intended circuit (or relay contacts, if that is what is being checked.

With the switch in the 'OFF' position, the meter will read battery voltage, as current is now flowing through the meter but not the switch.

When you turn the switch 'ON' the meter reading will drop right down, since it is easier for the current to flow through the switch than the meter.

However, there will always be a little current flowing through the meter unless the switch contacts are absolutely perfect (and probably gold plated!)

This small current is the VOLT-DROP across the switch and should NOT be more than about 0.2volts - if it is, there is too much resistance in the contacts.

The actual volt-drop across a circuit (or part of one, as in a switch) will depend on the resistance, as we have said, but also on the amount of CURRENT (Amps) flowing through that circuit Thus, if you were dealing with starter motor main cables and/or contacts, anything up to 0.5volts VD would be acceptable.

I hope that there might be some help in there.

Regards

3 minutes ago, caretakerplus said:

Firstly, you are wrong about immobiliser faults.

If (for example) you try to start the engine with an 'unchipped' key, the engine would start, but then would stop again within a second or two.

I am assuming that your 'new' column came with its ignition key? Hopefully, the immobilizer box as well.

Did you change the immobilizer box ?

If the key ISN'T matched to the immobiliser, then you are likely to get the results that I have described above.

 

If you have a multimeter, you can check the VOLT-DROP over a switch/relay contacts, or indeed the complete circuit by connecting the voltmeter to both switch terminals with the switch in its intended circuit (or relay contacts, if that is what is being checked.

With the switch in the 'OFF' position, the meter will read battery voltage, as current is now flowing through the meter but not the switch.

When you turn the switch 'ON' the meter reading will drop right down, since it is easier for the current to flow through the switch than the meter.

However, there will always be a little current flowing through the meter unless the switch contacts are absolutely perfect (and probably gold plated!)

This small current is the VOLT-DROP across the switch and should NOT be more than about 0.2volts - if it is, there is too much resistance in the contacts.

The actual volt-drop across a circuit (or part of one, as in a switch) will depend on the resistance, as we have said, but also on the amount of CURRENT (Amps) flowing through that circuit Thus, if you were dealing with starter motor main cables and/or contacts, anything up to 0.5volts VD would be acceptable.

I hope that there might be some help in there.

Regards

 

Thanks for your reply 

 

The behavior I have is that the starter motor does not spin at all, not even for part of a second, when I turn the key all the way, but I can get it spinning by bridging the wires on the plug.

 

The new column came with key but no immobilizer box, I just disassembled the new and old keys and swapped the immobilizer chip out, so the new key has the old immobilizer chip in it. With it like this I can get the car started by inserting the key and turning ignition on all the way and manually bridging the wires with a small wire. The car does successfully start like this, the issue is that bridging the wires is the only way of getting the starter motor to fire currently, turning the key all the way does nothing in either the old or the new ignitions.

 

Your info about measuring the switch contacts with a multimeter is useful though, I haven't yet done that - I'm waiting for a new ignition switch to arrive so I can test that on the car and prove that the fault is in the ignition switch. If it doesn't come soon though it maybe worth me following your advise, so thank you for that info!

 

The only tricky bit is I have to persuade the missus to come out and hold the key all the way round so I can play round the back of it with a multimeter... not sure how pleased she'll be with that, best make sure it's a sunny day 

I know what you mean about 'er indoors' helping out - I have had the same problem - it's lifting engines out that she really doesn't like

It seems incredible that you have had two ignition switches with the same problem, but from what you say, that seems to be the case.

One little warning about the VD check - When you release or turn 'OFF' the switch, the voltage immediately goes back up to battery voltage, this is OK if you have an 'auto-ranging' meter, but if not you need to make sure that the meter is disconnected before releasing/turning 'off' the switch, or you could damage the meter.

I can just imagine asking her to help lift an engine out  I might do it, just for fun, to see the look I'd get in return 

 

Yeah I know... as I was typing my original question I was thinking to myself 'I already know the answer' but it just seemed so unlikely that I had two with the exact same fault, that I had to ask someone, mainly for my own sanity! 

 

If this replacement comes and it still doesn't work.....