MK3 Warning Light Assimilator - problem solved

I have been working on my MK3 dashboard and lights. The last thing needing to be done was to get the Ignition (Warning) Light working. I discovered that the Warning Light Assimilator was missing and the wire that runs from the light to the assimilator had been cut.

I ordered a Solid State Assimilator from Old Britts (17-38706). I wired "E" to positive earth, "WL" to the light and "AL" to one of the alternator wires.

The light now comes on, but won't go out when the engine revs up. My voltmeter is showing 13.5-14.1 volts in the system when the revs get past 2000.

The bike has a Boyer ignition and a Tympanium Electronic Voltage Regulator and the warning light in my dash is LED (if that matters).

Any suggestions?

Thanks!

The earlier style work off ac current, I imagine this type do too. It might be that you're alternator is raising the system voltage but not putting out amps, but this seems highly unlikely. If you have an ammeter up to the task, you can check your alternator's output as described in the shop manual. You could also check the current going into the WLA. It sounds to me like you have a detective WLA.

On my MK2A I changed the bulb from incandescent to LED and the lights stays on, when I revert to incandescent the bulb goes out as soon as the bike starts. Either the LED being one way only is an issue or its low current draw.

kommando said:

On my MK2A I changed the bulb from incandescent to LED and the lights stays on, when I revert to incandescent the bulb goes out as soon as the bike starts. Either the LED being one way only is an issue or its low current draw.

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it sounds like it has a higher current draw than the incandescent, which doesn't make sense. What happens when you run the bike with the headlight off? Have you checked battery voltage at, say, 2000 rpm with both headlights?

kommando said:

On my MK2A I changed the bulb from incandescent to LED and the lights stays on, when I revert to incandescent the bulb goes out as soon as the bike starts. Either the LED being one way only is an issue or its low current draw.

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I am suspicious that the LED might be the issue. That the WLA allows a small amperage through that will light an LED, but not an incandescent.

I experienced the same thing when I installed a 3 phase alternator and an electronic regulator (purchased from cNw) but using the original assimilator and warning light. Matt Rambow had informed me that there was a way to adjust the wiring so that the assimilator and warning light would again operate as designed, but I do not remember what that was. At the time I opted to wire the warning light to the oil pressure switch sold by Don Pender (Madass140) who is regularly on this forum. While not "original", I find that knowing I have oil pressure is far more important than knowing if the electrical system is charging the battery. This alteration is easily reversible with no wires or parts compromised.

lazyeye6 said:

I experienced the same thing when I installed a 3 phase alternator and an electronic regulator (purchased from cNw) but using the original assimilator and warning light. Matt Rambow had informed me that there was a way to adjust the wiring so that the assimilator and warning light would again operate as designed, but I do not remember what that was. At the time I opted to wire the warning light to the oil pressure switch sold by Don Pender (Madass140) who is regularly on this forum. While not "original", I find that knowing I have oil pressure is far more important than knowing if the electrical system is charging the battery. This alteration is easily reversible with no wires or parts compromised.

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I have a homemade voltage based unit. You can buy them pretty cheaply, not much more than I paid for the parts for mine. It should work regardless.

The LED has no resistance and causes the solid state switch to enter a normally closed mode (light stays on) when it should be open.

-Knut

Problem solved. I puzzled through that the LED was the problem thanks to the help above. So I wired in an automotive horn/light relay, and let the WLA activate/deactivate the relay. The relay completes the circuit to the LED. Worked a treat. Perhaps a little convoluted, but whatever works. Using LEDs in the dash leads to a number of pitfalls.

I thought you were running an lED headlight, not warning light bulb. Does the MkIII WLA switch on the warning light's ground connection like on the earlier ones?

Many thanks for all this information guys. I am in New Zealand and have a 1975 Mk3 interstate, which is a Canadian model. I have just upgraded to a 3 phase system, using a Lucas 3 phase stator, a new rotor and a 3 phase podtronics unit. Everthing is working fine. I still have the Canadian "lights on" assimulator fitted with all the original wires attached, except for the 2 alernator wires from the original 2 phase setup. Looking at wiring diagrams, it looks like both types of assimulators (06-6392) for Canadian model, which turns on headlight whenever engine is running, and the rest of the world module (06-6393) which turns off the red warning light when it senses output from alternator, both of these require 2 inputs to the module to work, green/white & green/yellow to the 2 terminals marked AL on either module. As I have 3 wires now going to my Podtonics unit, I am thinking about removing this module with all the associated wires and installing one of the LED battery status monitors mentioned in threads on here, probably the sparkbright unit into the hole on console where current red light is. Do you really need the 2MC capacitor ? I have removed the 2mc capacitor, rectifier, sinners and taped up all the redundant wires on my original harness. Bike is running great. Will remove all these wires from a new loom I have next winter if all goes OK. I think for piece of mind fitting something that shows the battery is charging would be good. I can still run with lights on in daytime by switching to position 4 on key, which feeds from the battery instead of from the alternator output when the assimulator was used.

Years ago I was stuck. The ignition warning light would not come on. I diagnosed the warning light assimilator was stuffed so had a think about it. When the ignition is turned on first, the waning light is caused to glow because the earth return at that time, is actually earthing through the wire that provides current from the alternator, so when you start the bike up, and it starts charging, there is no current flow to cause the light to glow. I used this to work out the wiring for a 5 pin relay, and Bobs your Uncle, I had a bike with a working charging light. In the norton, the charging light does not form part of the charging circuit like in a car, so it works only because it senses the bike is charging..
Have a look.
So for about $5.00 and some wires I had a working assimilator which cost at that time in NZ about $80.00. Sorry parts suppliers, when you live in the wop wops, you have to improvise. The theorists out there will probably not be able to work out why my repair worked though. Its just Kiwi ingenuity and the no. 8 wire principle we have grown up with since Adam was a Cowboy.


Dereck

kerinorton said:

Years ago I was stuck. The ignition warning light would not come on. I diagnosed the warning light assimilator was stuffed so had a think about it. When the ignition is turned on first, the waning light is caused to glow because the earth return at that time, is actually earthing through the wire that provides current from the alternator, so when you start the bike up, and it starts charging, there is no current flow to cause the light to glow. I used this to work out the wiring for a 5 pin relay, and Bobs your Uncle, I had a bike with a working charging light. In the norton, the charging light does not form part of the charging circuit like in a car, so it works only because it senses the bike is charging..
Have a look.
So for about $5.00 and some wires I had a working assimilator which cost at that time in NZ about $80.00. Sorry parts suppliers, when you live in the wop wops, you have to improvise. The theorists out there will probably not be able to work out why my repair worked though. Its just Kiwi ingenuity and the no. 8 wire principle we have grown up with since Adam was a Cowboy.


Dereck

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Dereck,

I like it. I think I have a couple 5-pin relays around. I might consider replacing the WLA and my "solution relay" with your setup. Of course that would mean tossing the $28 WLA I bought. It would reduce the rat's nest of wiring I have next to my battery.

Michael

ewgoforth said:

I thought you were running an lED headlight, not warning light bulb. Does the MkIII WLA switch on the warning light's ground connection like on the earlier ones?

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I have a normal Lucas-type headlight and LED console lights. Yes, the WLA provides positive earth (ground) to the warning light. Negative is provided by the ignition switch.

Hi Michael. Remember I fit aint broken, dont fix it. I wrote about the use of that relay some 3-4 years ago if you can find it . Not sure I can, and i cant seem to find the photo of the setup right now.
Dereck

On my Mk3 , I added a wire to one leg of the 3 phase alternator wire and then plugged it in to the old alternator green/yellow wire, now unused, in the harness . Light works fine and doesnt come on at low rpms with the 3 phase setup. I have an LED bulb in the indcator which works fine . I found that if light stays on all the time reverse polarity of LED and it works as it should.

kerinorton said:

Remember If it aint broken, dont fix it.

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...and the corollary "If it ain't broke, fix it till you are"