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i have an 84 elcamino.i have new battery, starter and altenator. all have been tested and good. its not charging right. the voltage output on the altenator jumps around and it test good out of the car.if i use my headlights or heater the voltge immediatley drops and goes pretty much to the red.i did have one one fusable link blow i replaced it. i ant find anything wrong. please help me.i would really appreciate it. its driving me crazy. thanks
 

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Deputy Director Region 18 Participating Member
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I think there is 2 fusable link,one for the alt and the other is to power the "cab"(gauge, lights,raido ect.ect.)
 

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check to see if the brown wire that goes in to the plug with 2 wires on is not grounded on anything had that happen last week just a thought:smileyb:
 

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(@ gilby) I replaced the one going to the lights and stuff. The other one didnt look bad so i didnt mess with it. Think its bad?
 

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I chased a similar problem years ago on my '87. Hopefully, some of my experiences will be of help.
First, check the output at the alternator itself. Hook a good voltmeter to the big positive terminal on the alt. and a good engine ground. If output is OK there, your problems are downstream. Check your battery cables carefully at both ends of both cables. Make sure battery cable grounds are good, both at the block and where the ground cable pigtail attaches to the fender. A bad connection at the fender was my first discovery. Use serrated star washers for a secure electrical connection. Same thing with the positive cable connections at the starter. Backprobe the positive wires everywhere you can, both under the hood and in the cab.
Also, don't rule out a bad gauge if everything else seems alright. Still having a low reading after all my components and connections were verified as sound, I decided to pull the voltmeter gauge and check voltage at the gauge feeds. I found my gauge was reading about 1 1/2 volts lower than my digital voltmeter. A $25 eBay center cluster, a new heavier negative battery cable and some connection cleaning solved all my issues.

Bill
 

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(@ gilby) I replaced the one going to the lights and stuff. The other one didnt look bad so i didnt mess with it. Think its bad?
if you can,do a conductivety test wit a meter or a test light,it might be an intermitting short.(thats when the wire is broke inside the jacket and barley touching)
 

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it almost sounds like the voltage regulator in the alternator is going out, or possibly bad brushes. like stated above first check the voltage at the charging terminal on the back of the alternator, it should ideally be around 14 volts with the car running at idle or a bit above. if your voltage is low there, before you remove the alternator check the exciter wire. on the two plug pigtail, its usually the heavier one or the closest to the terminal, the smaller one is usually for the guage or an 'idiot light'. there should be power on it when the key is on or the vehicle is running. kif theres nothing, one trick, and ive done it on my own, is cut that wire and tie it directly to the charging terminal. it wont hurt anything on the older one wire internal regulated alternators, but if youre running the newer ones, from the late 80s or off a TBI or TPI injected motor it needs to be off keyed power otherwise it will drain the battery overnight or over a couple days.
another simple way to check if its charging is simply pull the positive batt cable while the car is running, if it dies, the alternator isnt charging suifficiently, or the heavy charging wire isnt making good contact somewhere. but be carefull this way, dont let the cable touch anything and dont let it run long with the cable off, when the motor is running off the alternator essentially it makes the alternator run at full output and can fry it.
 

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I don't have the diagram here right now, but you might check that major ground under the dash, above the park brake pedal. That black wire runs into the wire bundle up behind the dash, where many grounds are tied together. It may or may not have an effect on the charging situation, but worth a look anyway. The alternator excitation voltage may come from a fuse (?), so get a look at the fuse panel and R&R the fuses to make sure they are clean etc. Just a matter of eliminating as many things as possible.
 

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Discussion Starter #10
Testing straight from the altenator i have horrible output. It jumps around,and has never went above 12 volts. Whats the wire that runs from the connector part of the altenator to the back of the altenator. And also i took the check engine lights and such out there was no low battery one though so does that matter?
 

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See 350. Told you a post like this would get you some help. These guys are experts. Good luck and let us know how you make out.

Bob :beer:
 

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350,
By taking the bulb out of the charge indicator you eliminated the exciter voltage.
Read through this thread from a couple of weeks ago.
http://www.elcaminocentral.com/showthread.php?t=37799
There is some good info as well as some links for good reading on how it works.
 

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350,
By taking the bulb out of the charge indicator you eliminated the exciter voltage.
Read through this thread from a couple of weeks ago.
http://www.elcaminocentral.com/showthread.php?t=37799
There is some good info as well as some links for good reading on how it works.


So if i had it there and my bulb were to burn out my alt. Wouldnt work right. Wow lol. But ok seems simple ill try when i get a chance and see what happens
 

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Some cars had a resistor paralleling the gen bulb to keep the charge excitation voltage with the bulb out, but don't know about your Elco set up, and don't have a diagram handy....
Sounds like 464elky has the answer........put the bulbs back in. Why did you remove them?? Even with gauges, the idiot lamps tell you when to check gauges.
 

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Some cars had a resistor paralleling the gen bulb to keep the charge excitation voltage with the bulb out, but don't know about your Elco set up, and don't have a diagram handy....
Sounds like 464elky has the answer........put the bulbs back in. Why did you remove them?? Even with gauges, the idiot lamps tell you when to check gauges.

See i dont have a charge indicator. Just lights check engine choke and brake. I took them out cause the check engine light is annoying. Its on cause i put that new motor in and the hook ups to carb arent the same. Im gonna try and put them back in an check if there is good voltage on that other fusable link for starters.
 

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Charge indicator and oil and temp lights are in the area with the speedometer/clock-tach the best I remember - not over on the side with the check engine, brake and etc.
 

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Discussion Starter #19
Ok i was putting my lights in and the check engine and brake light are always on even with the key out. Its not the bright but there is still juice going to them. I took them back out so it doesnt drain my battery. Does that mean anything? Thanks again for your replys
 
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