Engine temp and other dash light on with single wire alt conversion 69 eldorado

[dirtycustom40]

I have a 69 eldoradro.I put a single wire alternator and hei ignition in it this weekend.I ran just the main wire from alternator to the battery I disconnected the voltage regulator plug.I then installed mechanical sun gauges.Interior lights were working and engine temperature light were off.Now when i open the door engine temperature light on dash comes on and all the idiot lights go on when i go to start car and they shut off when key is in run position.Interior lights still do not work.I ran power to distributor and volt gauge from same power source which was a big pink wire right below steering column.The gauge lights and the volt gauge share the same power and ground wire.Something back feeding and i need to split wires up?I seem to remember a engine temp light coming on when i opened door on a 67 eldorado maybe 30 years ago but cant remember cause or cure.Also this single wire hit 16 volt a couple times.The alternator was good a year ago on another vehicle that has been sitting.I will probably put the original alternator back on and reconnect voltage regulator.I havent tried it yet.Anyone ever run across this or have any tips?

[bcroe]

Its said an HEI must have an internally regulated alternator for reliable operation. 
But there is a lot of wiring associated with a mechanically regulated alternator; not
a good idea to just ignore it & hook up a one wire.  The one wire also doesn't have a
sensing lead connected to the distribution point; I would not convert to one.  Its
possible to plug in an adapter in place of the regulator, and use a regular 3 wire
internally regulated alternator.  Better yet to remove all the extra stuff, and properly
connect the couple remaining wires to the new alternator.  Bruce Roe  CLC # 14630. 

[Glen]

When you first turn on the ignition switch all the idiot lights come on as a bulb check.  After the engine starts the bulb check feature stops and the lights operate normally. 

There are three functions that use the same relay; key in alarm, horn and high temperature alarm.  Both the key in and high temperature alarms use the horn relay as a buzzer, only the horn uses the relay as a relay. 

There is a switch in the ignition switch that detects the key.  If the key is in the ignition and the driver’s door opens the horn relay buzzes and the high temp light comes on.  This is done by grounding the wire to one side of the light and the relay normally closed contacts.  Both he relay and the light have power. 

The same thing happens when the high temp switch closes grounding the same wire. 

The horn grounds the relay coil also but bypasses the normally closed contacts allowing the normally open contacts to close sounding the horns. 

[TJ Hopland]

What you have is a '3 wire' or '2 pin' internal regulator alternator.   The series was knows as the SI.  79 would have been a 10si.    The early GM alternators had an external regulator much like the generator and Fords did.   That extra wire is the wire that tells the alternator to 'turn on'.    The circuit is typically off a fuse that comes on with the key and then goes through the 'gen' light on the dash and then to the terminal on the alternator.  Without power on this terminal a stock '3 wire' will not output any voltage.    I dont think I have any diagrams of the external regulator ones but I believe they had that same wire connection to them.

A '1 wire' alternator is also known as a 'self exciting ' alternator.  They work more like a generator did where they depend on residual internal magnetism and a special regulator to generate the initial power needed to 'excite it'.  The exciter power is what powers the electro magnets to make them strong enough to actually generate substantial power.   One of the down sides is you often have to get the rpms fairly high to generate enough power to kick in the regulator and start generating real output.  Sometimes the part of the regulator also 'sticks' on so even after the engine is shut off the regulator stays on which will eventually drain your battery.   Some people offer kits to convert a standard unit to a self exciting unit.  Self exciting units are not that commonly used so they usually command a premium price for some reason.  Guess its because people can't handle that extra wire?  I have converted tractors and boats to a 3 wire because they tend to be more reliable and are much cheaper and easier to find.

Engine temp is the sensor on the back left corner of the left head.  When the sensor trips it grounds so if the wire has fallen off and melted into the exhaust or something that would cause the light and alarm to stay on.   Seat belt circuits if that car has em is often a place where people do poor jobs of hacking things to try and make the buzzer stop.  I thought that 'feature' came a few years later.

 

[bcroe]

I should have been more specific about alternator.The one i installed is from a 79 sedan deville.It has the external 2 wire plug with one wire from the plug going to the battery lug on the back of the alternator and the other wire is run to nothing right now.I believe this currently unused wire is brown.I read recently on a forum somewhere to run this brown wire from the alternator to the brown wire that went to the voltage regulator because this brown wire goes to factory gen light on dash.I havent tried it yet and am unsure if this is correct.Ive got alot goin on right now and probably wont get back to the car for another week.Thanks for the help.I really appreciate it guys.

That is right, the extra wire needs to connect directly to the GEN light.  Adapt your current wiring, or
remove the extra stuff & connect it direct.  Don't spin your wheels tying to understand what's going on,
until known flaws are fixed.  Bruce Roe