Ignition warning light & fuel tank sender

Post by **Jefftav** » Sun Oct 04, 2009 9:01 pm

A bit of an unusual one I think. I can start my engine and the red ignition light goes out and when I turn the ignition off and then on again to re-start the engine the ignition light doesn't come back on and then the other day with the engine running the red light came on and wouldn't go off until I turned off the ignition. I did check and the battery is being charged by the alternator even when the red light is on?

I have an alternator conversion and suspected maybe a wiring mixup but checked the small wire from the alternator up to the lamp holder at the speedo and there are no breaks or loose connections and I checked the continuity with a multi meter so thats seems OK. I suspect maybe the alternator but before I go changing anything I wondered if anyone else had this sort of problem?

As an aside the feed to the fuel tank sender isn't working but from the wiring diagram I have this is supplied from the voltage regulator behind the speedo so I don't think to two problems are connected?

1 thing I did do (and I don't know if this would cause this problem) when the engine was running 2or3 weeks back I accidentilly pulled of the earth connection to the battery (as I had just push it on to start the engine) and instead of turning off the engine I just put it back on with the engine running. So don't know if I have caused this problem myself.

Again thanks in advance for any help. Jeff

Post by **simmitc** » Sun Oct 04, 2009 9:50 pm

The voltage stabiliser on the back of the speedo is supplied from an ignition switched fuse. The same feed also supplies oil pressure warning lamp, heater fan, and wiper motor. Check to see if these circuits are working. If no, then check the fuses (worth doing anyway, the contacts can get dirty). If everything OK, then look under the boot floor, find the wire to the fuel tank sender unit, and short it to earth to see if the gauge then reads full. This type of fault is usually just a loose connection somewhere.

Ignition light is another question, I'll let someone else jump in on that...

Post by **bmcecosse** » Sun Oct 04, 2009 10:54 pm

Could be loose connection Jeff. Is the alternator definitely charging the battery - volts up at 13.8/14 ?? Is this a new alternator conversion - or just as before ? Has the old dynamo control box been taken away ?

Post by **Jefftav** » Mon Oct 05, 2009 5:49 am

THe supply to the heater, oil pressure light etc all work but I have no supply to the tank sender - I just ran out of time but will have to check the wiring through from the voltage regulator behind the speedo.

It is an old alternator conversion that I inherited and it has taken away the control box. With the engine running I was getting 13.9/14.0v at the battery so this would indicate the alternator is charging.

Thanks again

Post by **bmcecosse** » Mon Oct 05, 2009 9:07 am

Yes - certainly charging! But is that voltage at all conditions of red light on and off ? ie Is it charging no matter what the red light does ?

Post by **Jefftav** » Mon Oct 05, 2009 10:22 am

Yes the voltage stayed up at the 13.9/14v whether the ignition light was on or off so I am happy the alternator is charging the battery. When I am allowed out to play again I will re-trace my steps as it must be quite simple.

Post by **Jefftav** » Tue Oct 06, 2009 4:00 pm

Following on from my orginal post. I've had a look over the wiring again and when I earth the wire at the fuel tank sender the guage only goes across to half way and no where near full. I don't know how to check the voltage regulator as presumably the supply comes out of the regulator to the guage and through the guage to the sender?

I couldn't get the red light to come on at all today so I'm no further forward with this - maybe the fairies have sorted this problem?

Post by **bmcecosse** » Tue Oct 06, 2009 11:36 pm

As long as it come on when the engine is not running - and goes ouit (and stays out) while it IS running - all is well!

Post by **simmitc** » Wed Oct 07, 2009 1:05 pm

You're correct on power through stabiliser then gauge and to earth through sender unit in tank. By earthing directly at tank end you should get full scale deflection on the gauge. If not full deflection then (a) the earth wasn't very good (b) poor connection at gauge, (c) low voltage from either battery and/or stabiliser (d) gauge is faulty - probable order of likelyhood!

Try removing the speedo. You'll see the connections to the stabiliser and gauge. Make sure that you take a note of what goes there, but then try a feed directly from a known 12v supply to the stabiliser, and then return the earth from the other side of the gauge. It's a process of eliminating the various components. Again, good luck.

Post by **Jefftav** » Wed Oct 07, 2009 9:10 pm

BMC & simmitc, thanks for the help. Jeff

Post by **bmcecosse** » Wed Oct 07, 2009 10:28 pm

Jeff - had a great day on the Strathspey Steam Railway today - well worth a visit. My mate was driving - but Elf & Softy won't allow footplate trips (we do allow at Bo'ness) . I was about a week too early for best 'colour change' on the leaves on the A9 - but still spectacular scenery as ever! Hope you get that 'red light' problem sorted - don't want your car to be a 'red light' district!

Post by **Jefftav** » Fri Oct 09, 2009 8:23 am

Glad you enjoyed your trip up the A9, it's one of the best bits of my job getting to drive around the Highlands. I've never been on the steam railway but I have only heard good things about it so I must give it a go at some point. The red light has stopped coming on but don't know what I did so it might come back again. I am just about to fit the seats after I give the floor a second coat of paint so i'll be delighted when I can terrorise the neighbours again.