Alternator and lights issue.

[Tad Farmer]

Hello, I recently purchased a 79 Malibu. Was originally a 264ci with a 4 speed. Previous owner swapped in a 350 and put a automatic in. It has all aftermarket gauges and the interior is fairly beat up. The body is OK, no rust to speak of.

First Problem is kinda different. Lights, Been messing with them for a while. to no avail. They have just been acting weird, sometimes they work sometimes they do not. Turn on the left blinker, no blinkers up front but both left AND right blinker in the rear are flashing. Just super weird stuff like that. Well, I was working on it into the dark hours and just decided to call it a night, hood was up and the car was running, I still had the light switch on(no lights) Shut the hood and BAM!!! all lights worked blinkers worked everything just fine. So I popped the hood again, all lights went off. HMM, slowly closed the hood and seen that as soon as the latch touched the front clip it sparked a little and all lights came back on. I have been chasing this problem for 3 days straight! So long story short is I think it is a grounding issue and where would I start?

Second Problem. Car starts fine, runs fine but when I turn the key off the car still runs. I have to go to the engine bay and pull the plug on the alternator. Tested a couple things and if I leave the plug off the cars starts and shuts off like it is supposed to.

The plug has 2 wires. A red one that attaches to the alternator post. The second wire is yellow and goes to the cab and has a split to the electric choke(not sure if that is correct). The main wire coming off the post goes to the starter and splits off into the cab.. I have not been able to find it under the dash yet. So I am just not sure how to go about fixing it.

Thanks for taking the time to read my story here.

 

[Wageslave]

The ground issue is pretty simple to remedy. Check to see if you have a ground wire from your negative battery terminal to either your radiator support or your passenger fender. It should be like a 12 gauge wire, not the big fat cable that grounds to the block. If it is not there, add one on to your radiator support.

This provides proper grounding to the body, as the engine is more or less insulated from the body of the car by the rubber motor and transmission mounts.

The alternator issue is probably because someone removed the factory dummy light dash, and did not provide the proper resisted or diode blocked 12 volts that the sense wire on the alternator needs. If the sense wire gets straight 12 volts, when the key is switched off it will backfeed through the ignition switch to the coil wire and provide enough power to keep the HEI running.

You can either find the correct wire inside the dash if the factory cluster connector is still there or insert a resistor/diode/light bulb in line on the sense wire. Mine was the same way when I got it. I used a 194 bulb and socket out of a junk vehicle to get mine going at first, but the bulb tended to vibrate out of its socket and the alternator would stop charging, so I switched over to a big (size of your pinkie around by 3/4 inch long) diode. They are pretty easy to get a hold of at a parts store.

 

[Tad Farmer]

Hey thanks for the reply wageslave. What do you mean field wire? And does it matter where I put the diode inline on the wire?

Thanks again, very much appreciated.

 

[Wageslave]

The sense wire is the yellow wire on the 2 terminal plug on your alternator. I put mine inline about 6 inches before the alternator so my loom would cover the diode, but it will be ok pretty much anywhere as long as there is nothing else after the diode but the alternator. Keep in mind that they are polarized so if it is installed backwards your alternator will not charge so you may have to try it both ways.

If that is a splice where the yellow wire and the red wire go together then that would be a pretty good place.

Is there a black wire coming off of that splice?

 

[Wageslave]

I got my terminology mixed up, on the 2 prong connector the red wire that goes to the back of the alternator is the field terminal(Labeled 1 on the alternator case). The yellow wire is the sense terminal(Labeled 2 on the alternator case).

All the same instructions apply, just add the diode into the yellow wire coming out of the alternator.

I'll edit the previous posts to make it less confusing.

Sorry about that...

 

[Tad Farmer]

No black wire coming off the yellow wire. The yellow wire is spliced to the chime on the carb then runs to the cab. I will make a ground coming off the rad support and get a diode inline on the yellow wire. I will update this tonight. Thanks

 

[pontiacgp]

All the same instructions apply, just add the diode into the yellow wire coming out of the alternator.

don't you mean resistor?, a diode just regulates the direction of the flow of the current.....

 

[Tad Farmer]

From what I have read, the issue I am having is from feedback getting back to the alternator which is causing run on. The diode would solve the feedback getting back to the alternator. Or am I understanding the issue wrong? I try to research stuff that I am doing but I am a noob with this ki nd a stuff.

 

[pontiacgp]

From what I have read, the issue I am having is from feedback getting back to the alternator which is causing run on. The diode would solve the feedback getting back to the alternator. Or am I understanding the issue wrong? I try to research stuff that I am doing but I am a noob with this ki nd a stuff.

http://www.americanautowire.com/vie...t-continues-to-run-and-will-not-shut-off-why/
When I turn my car off, it continues to run and will not shut off. Why?
This can be caused by a few different things.The first item to check would be the alternator. There may be a feedback to the ignition switch from the voltage regulator field exciter wire. The other scenario that we commonly see is feedback from an aftermarket ignition system that utilizes an internal relay, or both a battery and ignition source to power the system. These are fairly common problems that people experience when using many aftermarket-wiring systems. Generally, an OEM harness will not have the problem of alternator “run-on”, as there is usually a resistance wire in the dash harness to keep this from happening."


a resistor in the wire is used to prevent the feedback to keep the engine running.......

 

[Tad Farmer]

So instead of adding a diode I would add a resister to the yellow wire as wageslave said correct? What size of resister?