Norton commando warning light

nortonisthebest · Aug 1, 2014

Hello,
The red charging warning light, on my 1973 Norton commando roadster, goes out after I start it but when I accelerate the light comes on. When I ease off the throttle to cruising speed the light fades out and goes out. When I open the throttle it fades back on. The key is switched to the first on position. When I switch the key to the second position the light goes out and stays out regardless of throttle position. I removed some of the old electronics and replace them with a Tympanium, rect/regulator, new assimilator, new capacitor 2mc. Any ideas? Thanks, paul

concours · Aug 1, 2014

Hi, welcome. Connect a voltmeter to the battery, rev up, switch key, etc. report back. :mrgreen:

texasSlick · Aug 1, 2014

Possibly a short to ground caused by something chafing when revving up. Most likely in the alternator leads to the regulator / rectifier, or the battery leads, but could be anywhere.

Follow Concours advice.

Slick

nortonisthebest · Aug 1, 2014

Hi,
Started up and rev up with key in first position voltage was 13 volts. Switched to second position, rev up and voltage was 13 volts, no change.

concours · Aug 1, 2014

nortonisthebest said:
Hi,
Started up and rev up with key in first position voltage was 13 volts. Switched to second position, rev up and voltage was 13 volts, no change.

Old assimilator failed? Same type as new? can you swap it in for test?
Did the assimilator light work properly before the changes you made?

concours · Aug 1, 2014

Voltage engine off was what? Engine idling?

nortonisthebest · Aug 1, 2014

Hi,
No, the assimilator was bad. Before I changed out the old electrical components I needed to do some welding on the frame. When I hooked the neg ground to the frame and started to mig weld the ground wire going to the zenor diode burned up. Actually all the ground wires burned up going to all the replaced components. I didn't try to run the bike until I replaced everything mentioned. That was the reason I replaced the mentioned electrical components. Everything works fine, turn signals, lights, horn etc. Note: I drove a ground rod into the ground and grounded the bike to it before finishing the welding on the frame.

texasSlick · Aug 1, 2014

13 volts engine running is a bit low....would like to see at least 13.7. I wonder if stator coils are in good condition. The only test for coil condition I can think of is to remove stator and ohm out each coil individually. But first .....How old is battery? Concours question about voltage when engine off is relevant ....less than 12 volts would indicate internal shorted cell that is overloading stator, and could explain low voltage when engine is running.

Keep us posted.

Slick

concours · Aug 1, 2014

nortonisthebest said:
Hi,
No, the assimilator was bad. Before I changed out the old electrical components I needed to do some welding on the frame. When I hooked the neg ground to the frame and started to mig weld the ground wire going to the zenor diode burned up. Actually all the ground wires burned up going to all the replaced components. I didn't try to run the bike until I replaced everything mentioned. That was the reason I replaced the mentioned electrical components. Everything works fine, turn signals, lights, horn etc. Note: I drove a ground rod into the ground and grounded the bike to it before finishing the welding on the frame.

Perform a continuity/resistance test on your stator wires next. You have the workshop manual?

nortonisthebest · Aug 1, 2014

Hi,
The battery is a new gel battery. I do have some shop manuals and i will check continuity. Question, why does the red warning light go out when the key is turned to the second position while riding the bike?

concours · Aug 1, 2014

nortonisthebest said:
Hi,
The battery is a new gel battery. I do have some shop manuals and i will check continuity. Question, why does the red warning light go out when the key is turned to the second position while riding the bike?

Once we determine what it ISN'T, we'll easily explain what it IS. :mrgreen: Troubleshooting 101.

The key's second position DOES include a functioning headlamp turned on and drawing current at that time, yes? Just so we're clear...

texasSlick · Aug 1, 2014

nortonisthebest said:
Hi,
The battery is a new gel battery. I do have some shop manuals and i will check continuity. Question, why does the red warning light go out when the key is turned to the second position while riding the bike?

I would have to study wiring diagrams to answer or speculate on that question. I am on the road....do not have diagrams. I 'll defer to Concours.

I assume you have two wire stator. Check continuity thru lead wires, and also from each lead wire to the stator frame. An internal short between adjacent stator windings can only be detected by isolating each coil and getting ohm value.

Slick

concours · Aug 1, 2014

The vibration isolating spring mount for the assimilator is in good condition, no accidental contact with movement?

concours · Aug 1, 2014

Is the bike fitted with turn signals? (direction indicators) Do they work the same in both key positions?
Next (refer to your manual's wiring diagram) you can jumper the #2 terminal on the ignition switch (white wire) with a jumper from the negative battery terminal, re-test.

texasSlick · Aug 1, 2014

@Paul (nortonisbest)

I leave you in concours capable hands....I must retire for night....early work tomorrow.

Slick

concours · Aug 1, 2014

texasSlick said:
@Paul (nortonisbest)

I leave you in concours capable hands....I must retire for night....early work tomorrow.

Slick

LOL, sorry, eyes burning too here in EST zone ttyl :lol:

nortonisthebest · Aug 1, 2014

Hi,
Thanks everyone for your reply's, it's very much appreciated. Earlier I indicated the wrong key positions. The first is parking and I can only turn the front head light on, bike will not start. Second position lights and ignition off. Third position should be ignition on only with no lights but I can turn my lights on and turn signals all work. Forth position ignition,lights and turn signals all work same as third position. Could this be part of the problem due to the third position working also the lights?

Biscuit · Aug 1, 2014

I had this very same weirdness years and years ago and although I 'm a little foggy on the exact issue I'm pretty sure it had something to do with the two stator wires. I seem to remember either one of them was disconnected or a broken wire, or they were wired together via a double bullet.

davamb · Aug 1, 2014

Hi NortonistheBest, what battery voltage do you measure with the engine not running?

texasSlick · Aug 2, 2014

nortonisthebest said:
Hi,
Thanks everyone for your reply's, it's very much appreciated. Earlier I indicated the wrong key positions. The first is parking and I can only turn the front head light on, bike will not start. Second position lights and ignition off. Third position should be ignition on only with no lights but I can turn my lights on and turn signals all work. Forth position ignition,lights and turn signals all work same as third position. Could this be part of the problem due to the third position working also the lights?

The symptoms you describe make more sense with switch positions such that warning light is on with lights on, not reversed as you first stated. This fact, plus low 13 volt reading points more to alternator stator as being defective. Post results of stator continuity tests for further advice.

As for switch position function, I will defer to Concours or other Cdo guys.....I am an Atlas guy. Got to go to work now...check in later.

Slick

Norton commando warning light

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