Lucas 11ACR Alternator Problems

[Westfaling]

I know that this a long shot as it's hard to diagnose this sort of thing on-line. Problems are:
1 No ignition warning light at any time - bulb and wiring to bulb okay
2 No apparent charging - voltage does not increase with engine running stays at about 12.5V.
I checked all the wiring from the alternator to the regulator (4TR) and relay control unit ( 16RA) seems okay.
I'd installed a new alternator but on the assumption that I may reversed the + and - wires to the alternator terminals and stuffed it - I had my old alternator reconditioned and fitted it today. It made no difference.
My car doesn't seem to have the warning light control unit shown in the parts books (158509) not sure if it's part of the 16RA unit. I suspect the control unit may be stuffed but I'm not sure that explains the lack of an ignition light.
Nick

[V Mad]

Hi Nick
Are you sure you still have the 11AC (or is it 11ACR which is non-standard)? Many cars have been converted to the 18ACR mainly because the wiring circuit is much simpler, and there are less connections to go wrong.

Assuming you have the 11AC then this uses the external 4TR regulator and 16RA which has the extra contact for the warning light. On the alternator there is an AL terminal which operates the 16RA relay when the engine runs. You should get around 3 volts there, if not something is wrong. The warninng light circuit needs to feed a small current to the alternator field + terminal to make it charge; the 16RA has an internal 60 ohm resistor in parallel with the lamp to ensure a small current flows. This should make the lamp glow but only dimly until you start the engine.

You could take some voltage readings at the various alternator terminals; this might help with a diagnosis.




If you have an 11ACR this has a built in regulator so the wiring will have been modified to suit.

[Motorcycle mad]

Hi Nick
You may find the attached link useful to you, in my answer to this thread I also attached a theoretical wiring diagram for the alternator (albeit upside down) this may help you figure out your circuit.
You will note that the warning light circuit is via rotor then through regulator to earth, when the engine runs the alternator puts power to the 16RA relay from the AL terminal on the alternator which pulls the contacts closed and switches off the warning light. So check the associated wiring and also try bridging out the regulator.
If you are suspecting an open circuit regulator remove the wire from the “F” terminal on your 4TR and put to earth, this will put the alternator on full output and you should see your volt meter climb quickly.
Do you have a dodgy warning light bulb holder?
Part number 158509 is according to the Rimmer spares list a seat belt buzzer, surely not connected with the charging circuit?

Good luck

Ken

http://www.stag.org.uk/forum/showthread.php?14645-Advice-on-over-charging-problem-please

http://www.stag.org.uk/forum/attachment.php?attachmentid=11348&d=1314979699

[Westfaling]

Guys
Thanks. The car is still 11AC no sign of wiring changes. I'm curious about the "warning light control unit" I don't think it exists. It shows up on page 05-54 of the parts manual but it's also labelled a seat belt buzzer in the parts list. I do have one of these on the relay panel but I think it is the seat belt buzzer - not working at present. I have the Lucas/Girling Confirmed Specs book for 71 Triumphs and it doesn't show up there.
Chris
The 3 volts on the AL terminal is that with the engine running or just ignition on?
It's been difficult testing the 16RA and 4TR as they both have moulded plug connections. I've just converted the 4TR to individual Lucar connectors due to a bad wire connection.
Nick

[Westfaling]

Just checked voltage at AL terminal. 0.3 volts with engine revving. TEsted my other alternator on the bench got the same thing. The testing instructions I downloaded suggested 6-8 volts.
Nick

[V Mad]

Nick, as you are not getting the output from AL (yes, engine running) on either alternator I suspect the regulator is not working, so as Ken says, try earthing the F terminal and see if the alternator charges.

[Westfaling]

Ken/Chris
Did as suggested and grounded the wire off the F terminal on the 4TR regulator. Voltage shot up to about 14.5V with the engine running. Sounds like I need a new regulator. Some interesting side effects of that test including washers ran at about 1/2 speed and the engine would not turn off with the ignition!
Nick

[Motorcycle mad]

Hi Nick
Pleased to hear you have the alternator working, although I am a little concerned with your comments that the washers are working at half speed, and that you were unable to stop the engine.
To me this suggests you still have a wiring fault, and I would delay replacing the regulator until you have checked and or re-checked the alternator wiring circuit, and may be even the ignition circuit, the engine should not have kept running, suggesting there is something causing a feedback on the power side which may have impacted on the charging.
Have you looked at my theoretical diagram I enclosed on my previous reply, it may help you understand the charging circuit better?
Also check your earth connections, battery to body, and body to engine.
Ken

[Westfaling]

Ken
Good point there are a few strange anomalies when I ground various components Everything is working - except the ignition light/charging circuit and I'm not blowing fuses but something must be wrong. The ignition circuit is all moulded plug-in connections except at the alternator so it's hard for these to be wrong.
Nick

[Motorcycle mad]

Nick
Please look at this attachment, and also scroll up and down the page, there is some other info there which you may have missed.

Ken

http://www.stag.org.uk/forum/attachm...8&d=1314979699

[Westfaling]

I'm making some slow progress on tracking down the lack of ignition light.
There must have been a fault in the washer pump ground wire I've isolated and run a new wire and the issue with the washer running is fixed.
I've changed the alternator control module and I now get 14+Volts with the engine running so I'm charging. Still no ignition light.
With the connectors apart under the speaker grille I've verified the light works by applying 12V between white and Brown/Purple wires. (Another error in the manual as it shows brown/yellow).
From the multi pin plug to the + terminal on the control module I've got 90 ohms resistance (ign on or off) that can't be right!
There's a connection point between brown & brown/purple wires shown near the alternator & control unit. Anyone know physically where it is??
Nick