Ignition light problem.

[macdonald.dm]

Hello.

I've just managed to fit my new dash (see "Dashboard re-design - stalks and all" below for 'stalk' pics hopefully!), but still have a li'l problem that was there before - a non-functioning ignition light.

I was hoping it was down to a poor connection on the dash itself, which would have been sorted as part of the re-fit - but, no. Also, the (new) indicator light works.

The alternator DOES work, as confirmed with a voltmeter.

What would help is to know the path taken by the 'indicator' wire from the alternator to the ignition light, and beyond.

I know it goes through the ignition switch, but I don't fully understand how it 'interacts' with the supply from the ignition switch to the rest of the ignition system (ie: coil and stuff).

Can someone treat me to a simplistic description of the path, something like: "It leaves the alternator, then goes to the ... then...then..." so my poor hapless mind can take it in?

Many thanks!

[macdonald.dm]

Re: Ignition light problem.

Oops, by "the (new) indicator light works" I mean the new indicator light BULB 'works' - but it just doesn't come on!

[austinm]

Re: Ignition light problem.

Hi Donnie,
Typical wiring for ignition charge indicator light is:-
Battery to Ignition Switch.
Ignition switch to Fusebox live side.
Fuse box to voltage stabilizer.
Voltage stabilizer to ign charge indicator light.
Ignition charge indicator light to Alternator.
The light works by going to earth through the alternator.
When the alternator is charging the voltage generated balances the positive supply through the light and it goes out.

Regards Austin

[ROBERT.JACKSON]

Re: Ignition light problem.

Looking at the Ford Capri wiring the ign wire (61)(blue) is from the alternator to the ign light. I would check your dash is earthed and that you hav a link from the ign switch to ign light.
On a Marina wiring the ign wire (brown/yellow) is from the alt to the ign light to the voltage stabilizer (B TERMINAL) to the ign switch (white wire) and a link to + (live) on the coil.

[macdonald.dm]

Re: Ignition light problem.

Austin & Bob - that's brilliant info, many thanks.

Based on your useful info on how it actually 'works', Austin, I'm going to try taking the ignition light lead at the alternator end to 'earth' with the ignition on (tho' car NOT running!). In theory this should test the wiring and indicate whether it's that or the alternator itself.

(It's always been a 'funny' alternator - it's a standard type for this car (well, a slightly higher output, I think - one used in later Cortina models), and a reconditioned unit, but ever since it was fitted I noticed that the engine need to be revved above, say, 2k rpm before the ign light would go out and the charge was delivered. After this 'blip' of the throttle, it would then charge properly even at tick-over, just as it should. Does this suggest anything 'strange' to anyone?!)

Thanks again, gents.

[austinm]

Re: Ignition light problem.

Hi Donnie,
If you intend to earth the indicator wire at the alternator as a test you should first pull the wiring plug out of the alternator.
If the indicator does not light up you need also to check if you have a live feed to the light when the ignition is on.
After this it is a process of elimination with the wiring to find the fault.
If the fault appears to be in the alternator do the plug connections match the pins inside the alternator? i.e.(Does the indicator wire connect to anything)

High revs to get the light to go out could be caused by the wrong size diameter pulley on the alternator (too large) resulting in the alternator running slower.
The alternator could have a faulty voltage regulator in it.

Good Luck

Regards Austin

[macdonald.dm]

Re: Ignition light problem.

Cheers, Austin - all good stuff.

I tried the 'earthing' test earlier today (yes - I removed the plug!), and zero - there's a wiring fault somewhere. Shouldn't be too difficult to find - it did work some time ago, so it's not missing 'links', or stuff like that!

As for the strange alternative behaviour, I can't remember whether I had to swap pulleys with the recon alt, or if it came with one fitted. Either way, there was no noticeable size difference, and I think it would have to be a significant difference to justify the 2k rpm 'blip'.

It does work ok once it's 'kicked in', so isn't the end of the world. But I must get that light fixed!

Cheers.

[macdonald.dm]

Re: Ignition light problem.

Sorted!

Disconnected the multi-plug on the bulkhead, did a continuity test and found the open circuit was on the 'engine' side. Began to unravel the insulating tape which was mysteriously covering the cable from the alternator to the bulkhead, and found the 'indicator' wire was cobbled together from at least three separate pieces over a distance of around 2 feet!! Good grief...

Ok, they had been soldered, but one had fatigued. It just had to be in the section which I'd so carefully re-routed and lagged a few months ago to avoid the side-exit exhaust.

Unravel, unravel...

Thanks for your help - superb!

[gouldsborough7]

Re: Ignition light problem.

Donnie
Funnily enough I am experiencing similar problems with my warning lights. Having just rebulit my dash (must be the season for it!)the lights for charging and oil pressure come ON together when I turn the ignition key to ON. After starting the engine, both light go OFF at the same moment.

The simple answer is probably I rejigged the wires wrongly.
I am a bit surprised as I labelled all wires with Dymo tape words before ripping off the old plywood dashboard. However, as this was the only penalty, I suppose I cannot complain - got it 99% right! I will have to climb under the dash at the weekend and see what the oil pressure light is connected to. If all else fails, I'll re-wire it completely back to the engine.

I'll put a note on this set of messages for info when I got it sussed.

Cheers
Mike

[macdonald.dm]

Re: Ignition light problem.

Er, is there any chance that it's all working fine?! You'd expect both lights to come on together, AND go off pretty much together too!

Worth trying to remove the wire from the oil sender and seeing if the oil light goes off while the ign one stays on? (But don't remove the alternator plug with the engine running - it'll damage it.)

Ok, it would be too good to be true if this was the case!!!

[gouldsborough7]

Re: Ignition light problem.

Hi Donnie
Yes, it did cross my mind that all was working OK, but I concluded that there would be a tiny gap between the 2 bulbs going out.

I disconnected the oil pressure light and fiddled about with a mulit-meter. One of the cables was 12volts live as could be expected when the ign key was turned ON, but the other was showing about 2volts. So I decided as a test to run a new cable to the sender at the engine, and see if that produced any conclusion.

My problem was: where is the sender? On my 2 litre Pinto (Cortina), there is a sender behing the distributor, and another on the same side but nearer the rear of the engine. I tested them both for EARTH, but no joy. Connecting multi-meter between POSITIVE on the battery and the thread emerging from senders, produced no circuit.

Have you any ideas? - 1) which one is the oil pressure sender? 2)is the other one for temperature gauge?
and 3) doesn't the oil pressure sender with engine OFF, start with a full earth connection, and break this when the oil pressure is to working level?

Cheers
Mike

[macdonald.dm]

Re: Ignition light problem.

Hi Mike.

Yes, I believe the sender located behind the distributor is for temp, with the oil pressure switch being further back tucked in behind the battery, and a bit above the starter motor.

If you simply pull off the electrical plug from the oil pressure sender, and turn on the ignition, you should see if there is any mixing of the wires! Hopefully, the oil pressure light should NOT come on, and the ignition light should. If you 'earth' the oil pressure wire, the light should come on - on both the 'temp' and 'oil pressure' senders, there is only a single wire going to each, with the other contact being earthed through the engine block.

(Other than that, they behave differently - the temp sender has a 'thermistor' inside, which is a resistor who's value alters according to temp, whereas the oil pressure sender is simple a switch which is either 'on' or 'off' - it goes 'off' with pressure.)

I'm surprised at your meter readings. Connecting one side to the batt +ve and the other end to the sender terminals SHOULD have given you readings - 12V from the oil pressure switch with the engine not running (0V with it running), and a variable voltage from the temp sender - it should have registered something!

(The sender wire which had 2V at it was probably the temp one? I'm surprised it was as low as that - I think I would have expected around 5V - but bear in mind that the temp gauge is supplied by a voltage regulator which I think supplies 5V.)

What happens when you simply remove the oil pressure sender's wire - does the oil light go out (with ignition switched on but engine not running)?

[gouldsborough7]

Re: Ignition light problem.

Hi Donnie
Armed with your ideas, and a few of my own, I enlisted a mate's help - a problem shared is a problem halved! Having identified/eliminated the temperature sender,we checked every conceivable permutation of connections between the oil pressure sender & the warning light on the dash with mulit-meter. The conclusions we arrived at were:
1) The sender was duff
2) The cable/circuit between sender & warning light appeared to be connected permanently to EARTH.
3) Just to confuse even further, the cable in 2) showed 1.5 volts at either end.
4) We thought initially that the POSITIVE cable to the warning light was somehow linked into the adjacent alternator warning light. In the end, we concluded that maybe the 1.5v cable was confusing things.
5) Conclusion: a) replace the warning light to sender cable - done; b)replace sender - going to happen tonight;
c) test it and keep finger's crossed!

Will post message to confirm outcome
Cheers
Mike

[gouldsborough7]

Re: Ignition light problem.

Have fitted oil pressure sender (only £5 from my local car shop), connected up earth cable from sender to warning light, and Bingo all is working properly again. Definitely one of my cheaper 'fixes'. It just took a lot of head-scratching to suss out the problem. Thanks Donnie for your ideas.

Cheers
Mike

[gouldsborough7]

Re: Ignition light problem.

By the way, while we are on the subject of new dashboards, here is a pic of my new dash.
Cheers
Mike