86 GN Won't Run Off Alternator???
- Thread starter dmk2
- Start date
The Light does not appear to be burned Out.
I have two wires comming out of the alternator. One is on the diod - red wire- the other is a plug with one brown wire comming out. If my alternator is feeding the car shouldn't I be able to dissconnect the negative lead from the battery and the car still run? and shouldn't the dash light come on when the battery is not charging?
One other thing, iI have had a problem with my dash lights. They dont come on. Headlights, tailights, Brake lights, signals, int. lights, dimmer... they all work.
I have two wires comming out of the alternator. One is on the diod - red wire- the other is a plug with one brown wire comming out. If my alternator is feeding the car shouldn't I be able to dissconnect the negative lead from the battery and the car still run? and shouldn't the dash light come on when the battery is not charging?
One other thing, iI have had a problem with my dash lights. They dont come on. Headlights, tailights, Brake lights, signals, int. lights, dimmer... they all work.
Not the bulb...
I'm not so sure about the bulb idea...
In posting some alternator/charging problems here, I heard that bulb idea more than once. In trying it out, I did the following:
1. Started the car. Noted that the lamp worked during starting. Once the car was started and idling, the lamp turned off.
2. With the car running and the ScanMaster set to read battery volts, pulled the lamp from the socket.
3. No difference AT ALL in voltage output... remained at a constant 14.0 volts.
Since the charging rate remained steady and was unaffected, there is must be more than a burnt out bulb to cause anyone problems. While a problem could possibly be related to the bulb circuit, the bulb itself does not seem to have anything to do with it in my experience/opinion. Now, it could be burnt out so that you cannot tell the charging circuit is having a problem! Check this during startup.. It should light up and tell you the bulb is OK.
I later replaced the alternator and it corrected my intermittent charging issues. Since you have done this and it didn't help, your original alternator is probably fine.
My recommendation is to check the sense wire and the connector that plugs into the alternator. If the car is started/runs without this plugged in or with a poor connection, the alternator will not charge the battery. Look for an open somewhere on this wire. Also check the terminal inside the connector and that it mates with the pin in the alternator. Everything must be clean and free of any corrosion. NOTE: if this is open/unplugged, the battery lamp will not light!
Double check the primary wire/cable running from the battery to the alternator. Maybe something managed to cut through it and isolated the alternator, however, I believe the lamp would light up in this case.
Hope this helps!
I'm not so sure about the bulb idea...
In posting some alternator/charging problems here, I heard that bulb idea more than once. In trying it out, I did the following:
1. Started the car. Noted that the lamp worked during starting. Once the car was started and idling, the lamp turned off.
2. With the car running and the ScanMaster set to read battery volts, pulled the lamp from the socket.
3. No difference AT ALL in voltage output... remained at a constant 14.0 volts.
Since the charging rate remained steady and was unaffected, there is must be more than a burnt out bulb to cause anyone problems. While a problem could possibly be related to the bulb circuit, the bulb itself does not seem to have anything to do with it in my experience/opinion. Now, it could be burnt out so that you cannot tell the charging circuit is having a problem! Check this during startup.. It should light up and tell you the bulb is OK.
I later replaced the alternator and it corrected my intermittent charging issues. Since you have done this and it didn't help, your original alternator is probably fine.
My recommendation is to check the sense wire and the connector that plugs into the alternator. If the car is started/runs without this plugged in or with a poor connection, the alternator will not charge the battery. Look for an open somewhere on this wire. Also check the terminal inside the connector and that it mates with the pin in the alternator. Everything must be clean and free of any corrosion. NOTE: if this is open/unplugged, the battery lamp will not light!
Double check the primary wire/cable running from the battery to the alternator. Maybe something managed to cut through it and isolated the alternator, however, I believe the lamp would light up in this case.
Hope this helps!
Hi dmk2,
Can you reword the above? You mentioned you have had problems with the dash lights (I assume in the past), but they all work OK now? Do they still work now with the non-functioning charging system, or did you get that problem corrected and now the charging system doesn't work?
I'm confused!
I'm at work, my service manual is at home. I will check into this tonight unless anyone else can help now? Is there a fuse that can blow and take out the charging system?
How about a fuseable link?
One other item that should be checked and checked well is engine block grounding. Not only should the ground cable at the battery connect to the engine block, there should be a smaller wire connected to the inner fender. In addition, there should be several ground straps from the fire wall to the engine block. While I don't know if these were missing would cause a NO CHARGE condition, it should still be looked at.
I also do not recommend disconnecting the battery while the engine is running... You might damage electrical components (Might work on your old 60's era muscle car, but here you have some more sensitive electronics to worry about!)
How about a fuseable link?
One other item that should be checked and checked well is engine block grounding. Not only should the ground cable at the battery connect to the engine block, there should be a smaller wire connected to the inner fender. In addition, there should be several ground straps from the fire wall to the engine block. While I don't know if these were missing would cause a NO CHARGE condition, it should still be looked at.
I also do not recommend disconnecting the battery while the engine is running... You might damage electrical components (Might work on your old 60's era muscle car, but here you have some more sensitive electronics to worry about!)
Steve Wood
Active Member
- Joined
- Jul 18, 2001
inst lts fuse, second row from top on the left side of the fuse panel.
Be sure the dimmer switch is not turned all the way down, tho.
Put a meter on the alternator and see if the large post is outputting voltage. If you don't have a meter, drive over to the parts house and ask them to test it for you...on the car.
Be sure the dimmer switch is not turned all the way down, tho.
Put a meter on the alternator and see if the large post is outputting voltage. If you don't have a meter, drive over to the parts house and ask them to test it for you...on the car.
- Joined
- Jun 28, 2001
i went thru the same thing summer before last. no alternator light, kept buying alternators, but when i least expected it the car shut down. at the track one day we put a voltmeter on the wire that fields the alternator and it was showing 6 volts then 8 then 10 then 6 = bad wire i guess, i pulled a new 12 guage wire to the alternator and have not had a problem since. cost me 4 new alternators over a 50 cent wire. but that's my crappy luck
I have just taken the instrument panel out, I put it back and wallah! The instrument lights work??? All the fuses check out OK. I keep thinking that the "VOLTS" Light in the dash should come on if the battery is not getting charged. I have a ECM on order tomorrow at 8am, so I am not so worried about blowing anything. I disconected the Alternator alltogether and the light in the dash didn't light up at all. I'll get a volt meter later tonight to check the alternator output. I'm told I should be getting about 13.5 v output on the large post of the alternator. What should I be Gettin from the plug side? At the risk of sounding stupid what wire feild the alteranator. The post or the plug
Steve Wood
Active Member
- Joined
- Jul 18, 2001
The volt lite should be on when you turn the key to "run" before you start the engine.
you should see 13.5-14.9 off the big post...
seems like I recall 10-12 on the brown wire. IF you see no voltage there, the alternator will not start charging. It is not good to put full battery voltage to that wire as it will damage the diode regulator. The bulb provides some degree of resistance to create a voltage drop.
you should see 13.5-14.9 off the big post...
seems like I recall 10-12 on the brown wire. IF you see no voltage there, the alternator will not start charging. It is not good to put full battery voltage to that wire as it will damage the diode regulator. The bulb provides some degree of resistance to create a voltage drop.
Steve Wood
Active Member
- Joined
- Jul 18, 2001
That is right, no voltage on brown when the key is in run, or the engine is running, and the alternator does not get "excited" to start the charging.
The brown wire basically runs from the ignition to the bulb to the alternator. Sometimes the bulb contact in the dash gets bad in them, the bulb does not burn, and the alternator does not charge.
These are easy, too....but different.
I bought a Limited a year ago that charged about half the time....you could listen to it idle and hear the engine speed up and know that it was not charging any more. After jacking with the bulb a bit, I finally followed the brown wire back, clipped it, put a dash lite in line with it, and connected it to an ignition source. Cured the problem for good. Bob, or John, once posted an appropriate resistance value to use instead.
The brown wire basically runs from the ignition to the bulb to the alternator. Sometimes the bulb contact in the dash gets bad in them, the bulb does not burn, and the alternator does not charge.
These are easy, too....but different.
I bought a Limited a year ago that charged about half the time....you could listen to it idle and hear the engine speed up and know that it was not charging any more. After jacking with the bulb a bit, I finally followed the brown wire back, clipped it, put a dash lite in line with it, and connected it to an ignition source. Cured the problem for good. Bob, or John, once posted an appropriate resistance value to use instead.
- Joined
- Jun 28, 2001
after i changed the brown wire i took the alternator belt off and started the car and the alternator light came on. thats the way i checked that. i turned out that i had 2 bad wires in my wiring harness and the alternator wire was one of them. it had continuity and only got weak when the car was hot ,
like halfway down the track.
like halfway down the track.
