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Alternator OK but system not charging

Alternator charging

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21 replies to this topic

#1 afewsubarus

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Posted 12 August 2013 - 09:02 PM

I have a 1985 wagon and the alternator checks out ok but the system is not getting a charge. Other symptoms include: the vehicle will not idle and the alternator, temp, and oil pressure gauges are not functioning.

 

I purchased the car a couple of days ago and the previous owner stated that the only know issue was the water pump. I pressure washed the engine to clean off the grime before I replaced the water pump so I may have inadvertently caused the problem. The battery terminals were also covered in a heavy coat of corrosive residue.

 

I have replaced the battery and tried two different alternators which are known to be good.

 

Any help with this issue would be greatly appreciated.



#2 john in KY

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Posted 12 August 2013 - 09:22 PM

Belt probably slipping  and sensor wires disconnected at sensors.



#3 ford'ssubaru's

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Posted 12 August 2013 - 09:58 PM

You have soaked the engine harness.  There is a harness plug on drivers' side engine compartment that gets brittle and temperamental.  I bet you disconnect your connectors and blow them out with air.  Install a little dielectric gease and it will be fine!

 

Eric



#4 afewsubarus

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Posted 12 August 2013 - 10:23 PM

I'll give that a try but it has been a few days since I washed the motor and the temp. around here has been in the 90's so I think everything is pretty dry in there.



#5 coxy

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Posted 14 August 2013 - 04:29 PM

Start checking the charge output at the Alternator and go from there. Remember Alternators also require Power to the Alternator to energise the Stator so they actually will charge properly so check the power supply to the Alternator as well.



#6 Cougar

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Posted 14 August 2013 - 04:39 PM

Hopefully you have already verified the fuses in the dash are good, preferably using a test light probe. If they are good then also check the fusible links inside the plastic box mounted on the coolant reservoir. Make sure they have power on both sides of the links and they are making good connection. Some folks have found bad connections under that panel causing trouble. One of those links connects to the alternator so that may be the trouble you are having. It is also important that the battery or alternator warning light works when you turn the ignition switch to the RUN or ON position. The lamp makes connection to the alternator exciter to get the field windings energized. 



#7 afewsubarus

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Posted 14 August 2013 - 05:43 PM

Thanks for the replies, I checked the fuses and the fusible links last night and they were ok, I am not getting any warning lights on the dash when I turn the key on. I have also noticed that the tach. is not functioning as well as the blower motor for the heater/ac. As I mentioned previously the temp. ,alt., and oil pressure gauges are not working either.

#8 Cougar

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Posted 15 August 2013 - 09:52 AM

You need to see why power isn't getting to those dash items, particularly the warning lights. Using a test probe light verify power is getting past the fusible links. Check the bottom side of the holder to make sure those connections are good. If that is okay then you need to check power getting to the dash fuse panel while the ignition switch is on. Verify all the fuses are getting power to them. If they are okay then you need to check the power connections to the dash cluster panel.



#9 ivans imports

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Posted 15 August 2013 - 09:54 AM

Fuseabble links in under hood fuse box use test light on both sides check for bad fussabble link or may have alt fuse under dash



#10 afewsubarus

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Posted 16 August 2013 - 02:28 AM

I checked the fusible links, all good both sides and underneath. I also checked the wires from the fusible links just before they disappear into the fender. Where are the power connections to the dash cluster panel. Is it the place where there are three plugs with multiple wires? If so, which of those wires should have a current running when the key is on? I checked the wires on the back of the alternator. The connector with two wires which I believe one of is the alternator field wire has power to one of the wires, I forget which color wire that is but it would be the one that as the connector is shaped like a T, it is the horizontal wire, or the top of the T.

Can I just run a wire from the coil or battery to the alternator fuse in order to supply the power to the alternator? I can get along without the gauges.

#11 ivans imports

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Posted 16 August 2013 - 08:52 AM

Same voltage on the big post of alt as battery ? if you jump alt may not shut off with key



#12 maozebong

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Posted 16 August 2013 - 09:09 AM

the small wire on the alt plug should have battery voltage. if it doesnt, your alt will not charge properly. 



#13 Cougar

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Posted 17 August 2013 - 02:49 AM

You need to check power getting to dash fuse panel while the ignition switch is on. You are most likely going to find out some of the fuses aren't getting power to them. The trouble could be with the ignition switch.

 

Both of the wires going to the back side of the alternator should have voltage on them while the engine is running. One wire is from the battery for the battery sense wire. The other wire is for the exciter that comes from the battery warning light. That wire will have no voltage on it while the engine isn't running. It will be energized when the alternator is working normally. 



#14 afewsubarus

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Posted 17 August 2013 - 02:51 AM

If the ignition switch is the problem, how could I determine that.

#15 Cougar

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Posted 17 August 2013 - 10:29 AM

The switch supplies power to the dash fuses so check to see if all of the fuses have power to them.



#16 Gloyale

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Posted 17 August 2013 - 11:13 AM

You have soaked the engine harness.  There is a harness plug on drivers' side engine compartment that gets brittle and temperamental.  I bet you disconnect your connectors and blow them out with air.  Install a little dielectric gease and it will be fine!

 

Eric

 

Alternator wires do not run through that connector.  They go directly back to thefusible links and fuse box.



#17 afewsubarus

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Posted 19 August 2013 - 02:37 AM

Problem solved, kind of. I plugged in an ignition switch from one of my few subarus and still had no power to the dash lights.  I checked all the fuses, the fuse marked engine/meter ( I think that is what it said do not really remember) looked fine but when I checked the backside only one end had power so I changed the fuse and when I started the motor it sounded different for about three seconds then the idle cut out and I noticed smoke coming from under the hood. Next I looked at the fuse and it was burned out. I realized I was starting to narrow down the problem. I put in a 20 amp fuse and had an assistant look under the hood as I started the car. Sure enough smoke started emanating from behind the carb and the fuse burned out. I unplugged what I believe is the connection for the automatic choke, replaced the fuse with the proper 15 amp fuse, turned the key and I had dash warning lights finally. Started the car, disconnected the negative battery cable and had a good alternator.

 

Now I need to figure out what is up with the choke and I should be good to go. I ran out of time as it was getting dark and the mosquitoes the size of hummingbirds were coming after me.

 

Thanks to all the board members who offered advice. The search option was also quite helpful in order to research past posts.



#18 Cougar

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Posted 19 August 2013 - 08:12 PM

Glad you found the trouble. Just for your info, it isn't a good idea to install a larger size fuse for a smaller one. You could end up with some real wire damage under certain conditions. Due to the bad short you got away with this one. You also shouldn't remove the battery connections when the alternator is working. Checking the battery voltage is a safer way to check the alternator output.



#19 afewsubarus

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Posted 19 August 2013 - 11:57 PM

I was aware of the potential for serious wiring damage. I bought this car to use as a parts car, mostly for the transmission, axles, and steering knuckles. I have a friend who needed a car for a couple of months so I figured I would get it running for him to use. I was not aware of any negative aspect of disconnecting the battery though.



#20 ivans imports

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Posted 20 August 2013 - 09:10 AM

The choke breaks the tab off the end of bimetalic sping and lets it move without moving choke bet its broken inside can drill out rivits to get it off



#21 Cougar

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Posted 20 August 2013 - 03:24 PM

Removing the battery from the charging circuit while being charged can create high voltage spikes, which can doom electronic devices. People get away with it but no good tech would recommend doing it. In the old days before solid state devices were used that trick wasn't a real risk.



#22 afewsubarus

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Posted 21 August 2013 - 05:07 AM

Thanks for the input, I'll take a look at it Thurs. when I have some time.







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