Can excess alternator output affect the ecu?

[Ghoste]

And more specifically, send it slowly packing?

[Chryco Psycho]

I am virtually certain this is why the recommendation is to change to the electronic regulator when changing the electronic ign to better control the voltage

[Ghoste]

Alright, I have two threads going on the same topic now.  At least my thought process was going in the right direction.
So a simple replacement of the ecu SHOULD fix my stutter issues?

[71_deputy]

I am virtually certain this is why the recommendation is to change to the electronic regulator when changing the electronic ign to better control the voltage

  also the higher the output the larger the wire should be from a stock wire system. any problems with the wiring will show it ugly head, bulk head connectors is the worst one.  larger output will also cause larger voltage spikes sometimes- so those spikes will cause electronic problems.

Even when I changed the wiring on the Chally- (bypassed the main power wires that went through the bulk head harness by hard wiring the wires through a larger gromment like the taxis/police packages did. ) to larger wires and a larger fusable link- alt is only a 75 amp one.  Reason??? the bulkhead terminals are only rated at 30 amps each- thats why there is so many problems with them melting- waytoo much current going thru them!!!


My two cents!!!

[Ghoste]

Well, I ordered a replacement ecu today so hopefully that should solve things.

[Plumcrazy]

You should always switch to an electronic voltage regulator when changing to electronic ignition.
A mechanical voltage regulator will cause voltage spikes from the alternator that can be seen on an oscilloscope.

[Ghoste]

It is electronic.  My overcharge was caused by another problem a few weeks ago.  Unfortunately, it was in one of those "damn the torpedoes" situations and had to drive it like that for 20 or 30 minutes.  Boiled the snot out of the battery too.

[Plumcrazy]

It is electronic.   My overcharge was caused by another problem a few weeks ago.   Unfortunately, it was in one of those "damn the torpedoes" situations and had to drive it like that for 20 or 30 minutes.   Boiled the snot out of the battery too.

If you boiled the battery the alternator was probably putting out close to if not more than 20 volts, enough to damage the ECU.

FWIW, if that ever happens again to you or anyone else.  Just disconnect one of the alternator field wires.  If you keep your electrical use down you could probably drive a couple of hours on the battery.

[Ghoste]

Actually, the problem turned out to be the exact opposite of that.  It was traced to one of the field wires having a break in it.  Don't just disconnect one field terminal in an overcharge, ground it out.

[Plumcrazy]

Actually, the problem turned out to be the exact opposite of that.   It was traced to one of the field wires having a break in it.   Don't just disconnect one field terminal in an overcharge, ground it out.

That can't be right.
One field wire provides battery voltage to the field windings.   A break means no charging.
The other field wire provides ground for the windings. A break means no charging.
It sounds more like you had a short to ground on the wire on the ground side of the windings.
Disconnecting one of the field wires would have stopped the overcharging.

[Ghoste]

On a dual field alternator?  We gotta be talking about two different things Plum.  I definitely had a break in the wiring.

[Plumcrazy]

On a dual field alternator?   We gotta be talking about two different things Plum.   I definitely had a break in the wiring.

If one of the field wires or the battery wire has a break (open) in it you won't get an overcharge condition.
Probably they meant to say short or maybe a break in the insulation.  If the wire that grounds the field shorts to ground you will definitely get an overcharing alternator.

Unplugging the field wires from the alternator will stop it from charging and save to from ruining a lot of hard to find parts

[Ghoste]

Plum, I will be the first to admit that electrical is by far the weakest link in my already very limited mechanical knowledge.  But, I can tell you with you absolute 100% undeniable fact that I had a break in the wiring from one of the leads coming off of one of the field terminals.  It was not shorted. It was a break.  There was a gap between two ends of a formerly joined piece of wiring and niether one of them were touching anything but an insulator.  I had an overcharge under this condition.  I ground one of those leads from the alternator to the engine block and the overcharge went away.
It happened and I repeated it as an experiment after your first post.  If you were here I could repeat it in front of you as many times as you wish.  I can't explain it my friend, I can only assure that it is what happened here without any doubt whatsoever.

[Nacho-RT74]

maybe is true that you have a break on the green wire lead of alternator BUT you have a short on some of brushes... check for plastic brushes isolators broken on the screw area. Maybe the brush prong is making contact with screw what is making a direct contact with chassis AND JOINING WITH THIS, maybe some short on rotor. Shorts on rotor ( even you have continuity on it ) is what commonly makes get high VOLTAGE ( not amperes ) outputs.

[Ghoste]

So why did it work normally both when I grounded the one field terminal to the block and again later when I repaired the lead and hooked it up as normal?