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Looking for some help! Previous owner had some un-diagnosed electrical problem. Battery light is lit on the dash, battery wont charge, alternator is brand new, belt is brand new.
Any advice?
Already checked the battery ground (looks new, don't see any issues with it) and I checked to make sure there's no draw when the car is off and doors are closed (there isn't). Next I popped open the fuse box under the hood - could it be those super corroded connectors, or should they not affect battery charging?
Any help is much appreciated! I'm down for trying anything. Previous owner had the glove box FILLED with replacement fuses and I think they've fucked with some of the interior fuses as well - the radio, clock, and interior lights don't turn on. I think that would be unrelated to charging issues, but it wouldn't surprise me if it means the previous owner meddled with stuff.
well from what you've posted it looks like the power wire to the alt isnt connected or its broken
as in the voltage isnt going to the battery to recharge it
on your underhood fuse box its one of the wires with the screws holding it down and on the alt side its the wire with the 10mm nut holding it on
id run a light tester on it and see if the wire is working and if thats good then go to step 2 if not then replace the wire its 8 guage if my memory is right
step 2
disconnect the wire from the fuse box and turn the car on
then with your light tester see if the wire has voltage and if it does then your alternators working
turn your car off and reconnect the wire to the fusebox
well from what you've posted it looks like the power wire to the alt isnt connected or its broken
as in the voltage isnt going to the battery to recharge it
on your underhood fuse box its one of the wires with the screws holding it down and on the alt side its the wire with the 10mm nut holding it on
id run a light tester on it and see if the wire is working and if thats good then go to step 2 if not then replace the wire its 8 guage if my memory is right
step 2
disconnect the wire from the fuse box and turn the car on
then with your light tester see if the wire has voltage and if it does then your alternators working
turn your car off and reconnect the wire to the fusebox
let me know how your testing goes
Hey there, thanks for the tips. I did the testing you mentioned today, and (unfortunately) the car passed all of the tests.
1.) I tested the connectivity between the alternator and the fuse box. Used a multi-meter that beeps when there's connectivity between two points, and connected it to the 10mm nut on top of the alternator (where the power wire is connected) and the other one on the screw terminal in the fuse box. Multi-meter beeped, everything seems to be able to connect. 2.) I tested the connectivity between the battery and the alternator. Connected the multi-meter to that screw post for the alternator power wire in the fuse box, and then to the positive terminal of the battery, multi-meter beeped. Everything seems to be able to connect there. 3.) I tested the connectivity of the ground cables to make sure they weren't damaged/corroded. First checked the one connecting to the transmission from the negative terminal, that one beeped, showing there was no damage to the cable. Then I checked the one connecting the negative terminal to the frame (near the passenger side headlight), multi-meter beeped, no connectivity issues there. Finally, I checked the one connecting the valve cover to a spot on the frame over by the driver's side headlight. Multi-meter beeped, no issues there. 4.) After making sure all of the ground cables weren't damaged, I decided to make sure they were properly grounding and contacting the frame. I pulled them off, making sure to remove any rust on the connector and sanding down the part of the frame they connect to, ensuring they were touching bare metal. The only one I didn't get to was the one connecting to the transmission from the negative terminal. I was able to clean the two that attach to the frame by either headlight.
Also, I measured the voltages.
Car Off Battery Voltage: 12.15 VDC Car On Battery Voltage (Let it idle for a minute/warm up): 14.45 VDC
Then I disconnected the alternator power wire from the fuse box and measured the voltage between that and the fuse box. Alternator was putting out around 2.3 VDC
Honestly, I'm not sure where to go from here! As far as I can tell, everything I've seen online seems to point to the things I've tested as common issues. Corroded cables, unclean grounds, broken alternators, etc. I was hoping for this to be a fairly obvious problem/fix, darn.
Anything I'm missing? Any advice on more stuff to check?
You should check under-dash Fuse No. 14 (10A) and whether there is power to the Blk/Yel wire going to the alternator. If that fuse is blown and/or there is no power to the Blk/Yel wire, the alternator will not properly charge.
Under-dash Fuse No. 14 and the Blk/Yel (IG) wire supplies the ignition input that turns on the alternator/regulator assembly. That fuse only gets power with the ignition switch in ON or START.
If you are not getting power at Fuse No. 14, then you would test the ignition switch.
You should check under-dash Fuse No. 14 (10A) and whether there is power to the Blk/Yel wire going to the alternator. If that fuse is blown and/or there is no power to the Blk/Yel wire, the alternator will not properly charge.
Under-dash Fuse No. 14 and the Blk/Yel (IG) wire supplies the ignition input that turns on the alternator/regulator assembly. That fuse only gets power with the ignition switch in ON or START.
If you are not getting power at Fuse No. 14, then you would test the ignition switch.
If the fuse is blown, the car wont start. Fuse 14 also supplies power to fuel pump, main fuel relay and ECU.
Hey there, thanks for the tips. I did the testing you mentioned today, and (unfortunately) the car passed all of the tests.
1.) I tested the connectivity between the alternator and the fuse box. Used a multi-meter that beeps when there's connectivity between two points, and connected it to the 10mm nut on top of the alternator (where the power wire is connected) and the other one on the screw terminal in the fuse box. Multi-meter beeped, everything seems to be able to connect. 2.) I tested the connectivity between the battery and the alternator. Connected the multi-meter to that screw post for the alternator power wire in the fuse box, and then to the positive terminal of the battery, multi-meter beeped. Everything seems to be able to connect there. 3.) I tested the connectivity of the ground cables to make sure they weren't damaged/corroded. First checked the one connecting to the transmission from the negative terminal, that one beeped, showing there was no damage to the cable. Then I checked the one connecting the negative terminal to the frame (near the passenger side headlight), multi-meter beeped, no connectivity issues there. Finally, I checked the one connecting the valve cover to a spot on the frame over by the driver's side headlight. Multi-meter beeped, no issues there. 4.) After making sure all of the ground cables weren't damaged, I decided to make sure they were properly grounding and contacting the frame. I pulled them off, making sure to remove any rust on the connector and sanding down the part of the frame they connect to, ensuring they were touching bare metal. The only one I didn't get to was the one connecting to the transmission from the negative terminal. I was able to clean the two that attach to the frame by either headlight.
Also, I measured the voltages.
Car Off Battery Voltage: 12.15 VDC Car On Battery Voltage (Let it idle for a minute/warm up): 14.45 VDC
Then I disconnected the alternator power wire from the fuse box and measured the voltage between that and the fuse box. Alternator was putting out around 2.3 VDC
Honestly, I'm not sure where to go from here! As far as I can tell, everything I've seen online seems to point to the things I've tested as common issues. Corroded cables, unclean grounds, broken alternators, etc. I was hoping for this to be a fairly obvious problem/fix, darn.
Anything I'm missing? Any advice on more stuff to check?
Thanks!!!
that was one hell of a explanation haha
from what you tested out
looks like your alternator is fine
now heres part 3
and thats going to be the battery
you say its not charging so im guessing your giving it a jump everytime your starting the car?
one simple test on the battery is to charge it fully useing what ever you have to charge it with
and if you dont have a charger know that autozone -advance auto and oreillys all charge batterys for free
and then once its fully charged leave it unconected overnight and see if it drains
1990 EF Battery Light
