Brake and charge light dimly lit.
#1
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Brake and charge light dimly lit.
Hello all I have a 87 2wd pickup and the charge and brake light stay dimly lit at all times. I have 14.3V at the battery all connections at the battery are good as well as engine and frame grounds. I have unplugged the master cylinder level switch and park brake switch. The switches work properly and turn the light on to a full light. Any suggestions on where to go next? Thanks
#4
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All brake lights and turn signals work correctly. So I took a peek underneath and found someone T-tapped the holy hell out of the rear end in a poor attempt to add a trailer pig tail. I think that may indeed be causing the issue/ backfeed
Thanks
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#8
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#9
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I'm thinking that sounds like a good next step. I checked the ALT plug for corrosion and it is clean as a whistle. I'm going to ohm out the yellow wire.
#10
That should have 12 volts while engine is running. If it doesn't, check other parts of charging system as described in my thread. Search "How Charging System Works"
Last edited by RAD4Runner; 06-20-2016 at 11:18 PM.
#11
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How about 14.27V DC while running? Sounds like the charging system is working pretty good.
#12
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That's what I cant seem to put my finger on. The charging system is working correctly and proper voltages are present everywhere yet the light is still dimly lit. Thank you RAD4Runner for the help. After I read my previous reply it sounded sarcastic and that's not how it was intended.
#13
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try hooking it up to another vehicle with jumper cables, both running, but with your alternator disconnected. no funny lights means you need an alternator. or you could take yours in to have it tested, some parts stores can still give them a full test and let you know if a diode is bad.
#14
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Seems like I remember a similar problem I had years ago with a Delco Remy system.
As I recall, it turned out to be a failed diode in the alternators rectifier bridge.
If possible, substitute another alternator and see what happens.
As I recall, it turned out to be a failed diode in the alternators rectifier bridge.
If possible, substitute another alternator and see what happens.
Last edited by millball; 06-24-2016 at 09:42 PM.
#15
try hooking it up to another vehicle with jumper cables, both running, but with your alternator disconnected. no funny lights means you need an alternator. or you could take yours in to have it tested, some parts stores can still give them a full test and let you know if a diode is bad.
However, I agree with having alternator tested.
WHEN THERE IS 14.7V at "L" (yellow highlight, charging voltage in normal range) on the negative side of the charge and brake error lights, the only way for charge and brake error lights to come on is
1) IF the positive sides (pink highlight in schematic) connected to 7.5 "IGN" fuse were much greater than 14.7V,
OR
2) If the diodes in combo meter (dash) were bad, and the voltage at IGN switch were much lower than 14.7V. But then, the truck should not run in this scenario.
Last edited by RAD4Runner; 06-25-2016 at 11:02 AM.
#16
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I should have been more specific, and I don't have an EWD to verify if it would work, but if you disconnected the big wire from the alternator that charges the battery while jumped to another running vehicle you may see the charging from the other vehicle and have no warning lite on. leave the control circuits connected to the alternator though. it's still a better test to pull it out and have it bench tested for "diode ripple" I think they call it.
#17
I should have been more specific, and I don't have an EWD to verify if it would work, but if you disconnected the big wire from the alternator that charges the battery while jumped to another running vehicle you may see the charging from the other vehicle and have no warning lite on. leave the control circuits connected to the alternator though. it's still a better test to pull it out and have it bench tested for "diode ripple" I think they call it.
Best of luck.
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