1966 ignition look wiring and function

[Maikel]

Good day,

I need some help in understanding my 66 ignition barrel and connection as the earlier cars were different or more simple.

On the 1966 car I have an ignition lock 34679 which has 4 terminals for 6 wires.
Earlier cars only had 2 terminals the brown/white and 2 whites on the other side. Turning key, current went through and ignition was on.

This LUCAS 34679 lock for 1966 cars also has the brown/white and the 2 whites and continuity is given when turning the key. This key only turns by 45° whereas the earlier barrels have a 90° turn.

But I wonder why the 2 brown/purple and the 1 brown/red are also connected to this ignition lock?
As I have no continuity from either of these and my Amp pointer dances to its maximum deflection when head light are on and also my ignition warning light goes off at about 900 rpm, where is used to turn off at 1.600 rpm.
I am wondering if there is a problem with the ignition lock. And what is the purpose of having those wires now at the ignition switch?
I already swapped the regulator twice and the 3AW switch is new. Voltage at Batterie when running is 17.4 V

Ignition and Amp on 1966 car.png (238.48 KiB) Viewed 1422 times

Any feedback is welcome
Many thanks
Maikel

[MarekH]

If you have a high voltage produced by the alternator, then the regulator is not regulating. It does this by switching the field coil on and off such that the average voltage becomes ~14v. One side of the field coil is connected to the battery positive feed and the other goes to the regulator. When the brown/green F- wire is also switched to 12v, there is no voltage across the field winding and the alternator output is zero. When the brown/green F- is switched to earth, there is 12v across the field and the alternator turns on to its maximum voltage. The regulator keeps flipping between the two such that output always kept at ~14v. Having a continuous higher voltage than this suggests the green/brown wire is being shorted to earth or that the regulator is faulty, such that its F- terminal and earth are effectively connected.

A car which was originally designed for a generator, not an alternator, will want to have a switch arrangement which cannot discharge the battery through the regulator when the ignition key is out, hence the complicated wiring connections, which will have changed through time.

You can make a truth table for your switch to determine whether it is connecting the right components in each switch position.

kind regards
Marek

[Maikel]

Hi Marek, good you are there.

Many thanks for the prompt reply and it seems you have covered this topic before.

OK, the car was running for years and step by step I realized the battery ran flat, so changed it but went totally flat within 3 month again. More and more also the ignition control light was more off than on in the lower rpm region and recently it only comes on occasionally at idle speed or just above.
The connection and wiring is set all correctly and it is all original equipment, rebuilt alternator, a correct regulator and a new 3AW switch. All new wires with proper plugs. We measured 14.1 V at the battery, but alternator output was 17 V.

I measured the ignition switch before as I stated in my first post. I had no connection between the brown/purple and the brown/red. I just tried again because you said there should be a flow when key is turned on and indeed, I found one precise position where I also have a flow. But that position you only find by try and error whereas the ignition brown/white + white stays on all the time.

have added a video here on my website. as in normal of position you would simply jump over the point where you have continuity.
https://etypes1.com/malfunction-ignition-lock/

So, as one flow is coming via the brown/purple to the ignition switch and should continue via the brown/red to the Ammeter I only then have a reading at the gauge, right? With head lights off the Amp was showing charge, but as soon the head lamps were on, the pointer started dancing crazy. I tend to blame the scarse/random switch connection for this. We have ignition on via the brown/white to white, but only random flow between B/P and B/R wire.

When you say the alternator is charging the battery, which way does it go? Does it take the loop via the ignition switch to the Amp gauge and back via the brown/white cable to the battery?

It that the meaning of the direction pointer in the diagram?

I have been looking for a replacement ignition switch 34679 but it seems they are not listed. Any chance of repairing the original? Could this malfunction of the ignition switch cause the malfunction of the ignition control light and poor or no charging? Obviously, if the Amp gauge circuit is not closed at the switch, the Amp gauge stays in the middle and appears to be OK.

Many thanks again.

Maikel

[MarekH]

I have never even seen a 1966 car before, but you seem to be describing a faulty connection either at/in the ignition switch or at the ammeter. I'd clean all of the connections and the inside of the switch.

Like I said, you need to make a truth table to determine what should be connected to what when the ignition switch is at its various positions.

The ammeter and ignition light are very simple to explain:- The ammeter needle simply records in which direction current is flowing and current only flows from a high voltage to a low voltage. This means that when your alternator is running and charging, the NW leg of B+ at the alternator and at the lhs of the gauge (as pictured in the diagram) is at a higher voltage than N at the rhs of the ammeter and at the battery positive terminal. This what you'd expect as the alternator puts out an expected 14volts and a 12v battery typically has about 12.8volts at its positive terminal. The battery gets charged as the current flows from the alternator, through the ammeter from left to right and on to the battery positive terminal. When the ammeter needle is pointing to discharge, the battery voltage of ~12.8v is higher than what is at NW - the alternator is not charging.

The alternator charges when there is a voltage across its field coil. One side of the field coil F+ has to see 12v and the other side F- has to see earth. When this happens, the alternator charges to its maximum voltage, about 18v if it is spinning fast enough. To stop the battery acid from being boiled out by this high charging voltage, a regulator is fitted. This keeps turning the F- earthing connection on and off very rapidly, so the average measured alternator DC voltage is kept to a safe 14volt output. (The alternator charges the battery with short high voltage pulses, but the average works out at 14v because the regulator keeps turning the alternator on and off about a hundred times a second. The battery acts as an energy store so the rest of the car doesn't see the pulses.) Accordingly, when the ignition switch is "on", as you report a 17.8volt alternator output (not 14v), you must have the field permanently connected with 12v across it. Firstly, I'd ascertain whether F- and F+ at the alternator are isolated from the alternator casing. If F- is accidentally shorting to the casing, the alternator will always go to maximum output voltage when F+ sees 12v. Similarly also for the NG wire, if that is shorting to earth. Offhand, I don't know what is inside your regulator unit, but it will also send your alternator to full output anytime F and - are permanently connected when F+ sees 12v.

You need to be a bit more specific about "not closing the amp gauge circuit at the switch". The gauge being in the middle either means it is not connected or the voltage on both terminals is the same.

Your 3AW simply powers the ignition warning light. Typically, the alternator puts out 8v AC from the AL terminal onto the NY wire to power a bimetallic strip which opens a contact to stop the light from being earthed (its other side sees 12v from the NB wire). Most alternators "get going" at just below idle rpm, so it suggests your old setup was not charging at low rpm, but is now. It also makes me question what you are measuring when you report the high voltage - you can't have 17v at the alternator B+ and 14.1v at the battery now but 17.8v at the batterie (sic) earlier. The former implies it is working correctly at the battery and you have mismeasured at the alternator and the latter implies there is a serious non-regulation problem. You need to clean all of the connections (including the switch) in the chain.

kind regards
Marek