Ignition Light

[jjc]

Would be very grateful for a bit of help.  I'm not familiar with GT6 Mk2 but have been rebuilding the gearbox so engine and box out.  Actually in and out a few times. Somewhere in all of that the ignition light no longer comes on.  There's a Brown/Yellow wire coming out of the loom by the alternator with a bare end. Live with ignition on.  Looks as thought it might be the ignition light wire heading for the alternator but I cannot see anywhere it might connect.  I don't remember breaking this wire off but hoisting engine and box out on you own all kinds of things happen.  Anyway would be very grateful for any help, especially pictures.  JJC

[Pete Lewis]

The brown/yellow is the link between alternator and the warning lamp bulb.

what alternator have you got ???

Pete

[Colin Lindsay]

Most common Lucas or period alternators have three terminals, two large and one small, or else some have just one of each. The thick yellow / brown wires go to the larger terminals, and the thinner yellow / brown to the smaller (although on some I think it was brown / green at the alternator but brown / yellow by the time it reached the red lamp). However if yours is brown / yellow beside the alternator, then as Pete says that's the one that triggers the red warning lamp and should be connected to the smaller terminal.

[jjc]

I'll have a look for the alternator label. There's a single plug connected to the alternator with a sealed cable carrying two cables, one large, presumably power.  There's no other obvious terminal unless it's hidden under the plastic cover hence my difficulty finding where this wire that's flapping about should go.  Might just earth it and see if the ignition light comes on.  I'll post a picture tomorrow.  

[Pete Lewis]

if the terminals are blade (Lucars) there is usually 2 main charge terminals 30amp blades both connected together

alongside is a 17amp smaller blade which your lost wire should connect 

earthing the lost wire wont work its voltage sensitive and the alternator feeds this to illuminate the warning lamp when not charging 

Pete

 

[jjc]

Pete - thanks for that.  In the picture below you can see the plug which goes into the back of the alternator. That plug has two Lucar connectors, only two and the third hole on the alternator hasn't got a spade connector.  You can see the Brown/Yellow wire which isn't long enough to reach anywhere I can see.  It's got 12v with ignition on.  I might just check the bulb!

[Colin Lindsay]

A live wire hanging about in the engine bay can't be right under any circumstance. I'm paranoid about fires! Can you remove that black plug and let us see what's behind? The rear panel looks very like this one, which has three:

[Pete Lewis]

colins pic shows clearly the 2 big blades   and the smaller one you need to connect 

without it the alternator can go quite wild 

Pete

[jjc]

6 hours ago, Pete Lewis said:

 

earthing the lost wire wont work its voltage sensitive and the alternator feeds this to illuminate the warning lamp when not charging 

Pete

 

The brown/yellow wire according to the wiring diagram is powered from the ignition switch. Doesn't that turn the light on which then goes out when the alternator produces 12v that's how you know the alternator is charging.  I'll post a picture with the plug off tomorrow. Thanks for your interest - I'll get there eventually. Never had this much trouble with the TRs. 

[Pete Lewis]

the ign lamp feed is the battery sensing control feed  

you wonder why its been disconnected 

earthing may well put the light on , but that doesnt help the control of the alternator 

 

Pete

Edited November 30 by Pete Lewis

[Colin Lindsay]

13 hours ago, jjc said:

The brown/yellow wire according to the wiring diagram is powered from the ignition switch. Doesn't that turn the light on which then goes out when the alternator produces 12v that's how you know the alternator is charging.  I'll post a picture with the plug off tomorrow. Thanks for your interest - I'll get there eventually. Never had this much trouble with the TRs. 

It leaves the ignition switch as white, but changes at the bulb to brown / yellow, from there to the control box, and from there to the alternator / dynamo. The end that's beside the alternator emerges from the loom for that reason - it's close to the alternator so probably isn't the connection for any other component. The line is live with ignition on, as the power effectively loops out from the battery through ignition / bulb / control box and so the bulb shows power on, but the alternator then breaks the loop when up to speed and the light goes out. Thinking laterally here again... if you get 12v with the yellow / brown cable tested, does the bulb light up at the same time then go out again when the tester is removed, or if you safely earth that wire? (don't forget that the bulb may have blown too in the interim)

[Pete Lewis]

18 hours ago, jjc said:

Never had this much trouble with the TRs. 

what model has no bearing on this , it is basic alternator connections used by all lucas and delco alternators of the day   

i would get it connected asap or the next post will be black bulbs and a cooked battery 

Pete

Edited November 30 by Pete Lewis

[jjc]

4 hours ago, Colin Lindsay said:

It leaves the ignition switch as white, but changes at the bulb to brown / yellow, from there to the control box, and from there to the alternator / dynamo. The end that's beside the alternator emerges from the loom for that reason - it's close to the alternator so probably isn't the connection for any other component. The line is live with ignition on, as the power effectively loops out from the battery through ignition / bulb / control box and so the bulb shows power on, but the alternator then breaks the loop when up to speed and the light goes out. Thinking laterally here again... if you get 12v with the yellow / brown cable tested, does the bulb light up at the same time then go out again when the tester is removed, or if you safely earth that wire? (don't forget that the bulb may have blown too in the interim)

Earthing the loose wire I'm worried about does indeed turn the ignition light on as expected (so bulb is ok). The bulb doesn't come on so far as I know when checking the volts on the wire with a voltmeter because the meter is effectively high resistance. Picture below shows the plug coming from the loom which goes into the back of the alternator.  Only two connectors.  Two possible routes now - either try and find the correct connector in the back of the alternator and wire the loose wire into it or think about connecting the rogue wire to the output of the alternator on the starter solenoid for instance. Just a bit dubious about that as I'm not familiar with the circuitry inside the alternator doing voltage control.  It's our son's car I haven't driven it so don't know if during his more than 10 years ownership the ignition light ever worked. But the alternator certainly did or he would have noticed a flat battery. JJC

[johny]

Surprised this is proving to be such an issue as surely the great information in the free to download triumph workshop manual covers it all?

[Colin Lindsay]

So there are only two connectors on the rear of the alternator? That plug has two but how many are there on the other side... can you photograph the rear of the alternator in closeup?

[Pete Lewis]

thats a std plug body  some manufacturers used two 30 amp blades  triumph and many used just one 

inside the alt.  cover the two are riveted together   the smaller has always been the brown yellow warning light connection

back in the   early days with relatively slow idle and low max rpm diesels  you either had a very large crank  pulley

the simple cure was to fit a much higher wattage warning bulb as this would control the cut in speed to a lower rev 

range .

sorry but no need for pages of waffle   just connect it as it should be . job done 

Pete

 

[jjc]

16 minutes ago, Pete Lewis said:

 

sorry but no need for pages of waffle   just connect it as it should be . job done 

Pete

 

So I took the cover off the alternator just now. Picture below. To connect it as it should be the loom should have obvious connections in the right place.  Why it hasn't I don't know because I'm picking up the bits from someone else's rebuild and I don't know what he did to the alternator, the loom, or anything else for that matter.

[Pete Lewis]

thats very normal you can see the twin main charge 30 amp blades  and next to them  is the 17amp blade for the WL

it doesnt matter which of the twin blades you use for the main charge cable they are one of the same . 

to use the normal harness plug cover you will need 90 deg angled entry lucar blades but if you dont use the plastic cover then normal straight lucars will fit just as well but less the clip on terminal cover 

if you are stuck i have aload of covers and lucars if you need any 

there are places that will test the alternator if you have some hang up about is connections 

but that pic is a very normal  Lucas ACR unit used by the many 

Pete

Edited December 1 by Pete Lewis

[johny]

5 hours ago, jjc said:

Right I'll wade in again😁I see that isnt exactly the same as the Triumph original and think maybe the regulator has been changed because it looks newer. However I agee the two big spades are the power out and the small spade is the feed from the ignition light (brown/yellow) but I think there needs to be a battery sensing wire to that spare spade fixed by the bottom left of the four screws. This should be a small brown wire and Im not sure but can I see it cut short in the loom of your previous photo?

[jjc]

5 hours ago, Pete Lewis said:

 

if you are stuck i have aload of covers and lucars if you need any  

Pete

Pete - that's very kind of you. I've worked out what happened and fixed it, needed a bit of loom rectification hopefully it'll work ok.  Now I can get back to how the whole thing started which is to get it repainted once I've road tested my gearbox rebuild.  JJC

[johny]

Heres what I mean?

[Pete Lewis]

separate battery sensing was often used by vauxhall but not used by Triumph Rootes or BMC

for this the delco (vauxhall) unit often had a terminal on the exterior of the main case

i woud stick to brown /yel onto the small terminal and sleep easy 

Pete

[johny]

Beg to differ Pete. This is from the GT6 manual and looks like both battery and machine sensed alternators were used, at least for the mk3, and I think thats what jjc has fitted. The Lucas part number would be useful...