When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Background: I bought the truck about 2 weeks ago, and it would only start by a push start and popping the clutch. I had some electrical issues at the fuse box, thanks to this thread here: https://www.yotatech.com/forums/f131...86/index2.html I was able to follow RAD4runner's instructions and found the source of my problem and that issue has been fixed. I removed all the pins and connections(one by one so they don't get mixed up), replaced all the fuses and cleaned it all up, then I chased the wiring to find corrosion down the line, I fixed that. The initial problem was the power from the fuse box wasn't reaching the ignition switch or fuse box in the cab due to corrosion in some of the wiring. The CHARGE light was always on since I bought the truck.
Current issue: So now that I have all my electrical working, the only issue I have is the CHARGE light is still on(only dash light which stays on after start and even some driving). The battery has held a charge, no problem, the truck starts so easily now. Voltmeter applied to the battery terminals show 12.84v when off, 12.76v with the ignition on, 14.27v @ idle and 14.22v @ idle with lights on. Not exactly sure on the procedure to checking an alternator, can anyone share some tips on how to test an alternator? Also, if someone has experienced the same issue and might know how to get the CHARGE light to turn off, I'm all ears.
... Current issue: So now that I have all my electrical working, the only issue I have is the CHARGE light is still on(only dash light which stays on after start and even some driving). The battery has held a charge, no problem, the truck starts so easily now. Voltmeter applied to the battery terminals show 12.84v when off, 12.76v with the ignition on, 14.27v @ idle and 14.22v @ idle with lights on. Not exactly sure on the procedure to checking an alternator, can anyone share some tips on how to test an alternator? Also, if someone has experienced the same issue and might know how to get the CHARGE light to turn off, I'm all ears.
How about your brake light? IF there is charge fault (L-Wire goes low, instead of 12V), the brake light should also come on.
PRACTICALLY YOUR ALTERNATOR IS PRODUCING THE RIGHT VOLTAGE WITHIN NORMAL RANGE (13.5 TO 15.1V) WITH ENGINE RUNNING.
HERE'S THE CHARGE LIGHT CIRCUIT:
Things that could cause Charge Light to come on...
(1) Actual alternator fault,
(2) Fault circuit thinking your alternator is not putting out proper voltage (hence, you're getting a false alarm).
(3) Something starting to go bad in alternator that plain multi-meter reading cannot detect but fault circuit is detecting it; i.e., bad waveform, rectifier starting to go bad... (I suggest having it tested at shop / store AFTER YOU DO CHECK I'M DESCRIBING BELOW)
(4) Something else on the yellow highlight line in schematic shorting to ground and forcing that line to go low.
Quick Checks before you take it to the shop/store: With engine on.
Measure voltage at each side of "Charge fuse" (below)
Disconnect "CHARGE" fuse. Charge Light AND brake light should go out. Alternator output should stay normal. (L- wire / charge fuse circuit is only for fault indication. Will not prevent alternator from working.
Measure voltage on each side of the "Charge" fuse socket.
Engine off, All off:
Disconnect everything from the alternator terminal stud/screw.
Measure resistance to ground. You should have resistance in multiples of Mega-Ohm. Else, you have rectifier bad/going bad.
With Charge fuse still out of the socket, measure resistance of each side of socket to ground.
Last edited by RAD4Runner; 05-09-2017 at 01:30 PM.
How about your brake light? Brake light is not on.
With engine on. Measure voltage at each side of "Charge fuse" (below) 4.3v both sides of fuse. Disconnect "CHARGE" fuse. Charge Light AND brake light should go out.CHARGE light is still on. Measure voltage on each side of the "Charge" fuse socket.4.3v left side, 0v right side
I'll try to get to the Engine Off test tonight or tomorrow, got busy today. Thank you for giving me a solid starting point. Also, my brake light doesn't come on at all even with the e-brake on, should I get that working first?
My 1985 Toyota 22R pick up has both the brake light and charge light on I just replace the battery this morning and the light is still on last week when driving the truck with a friend we smelled something terrible found out it was the 80amp fuse under the hood, replaced it and now I’m wondering if the alternator is the problem? Sidenote neither one of these lights were on prior to the battery needing replaced and or the fuse burning up any information would be helpful thanks guys
My 1985 Toyota 22R pick up has both the brake light and charge light on I just replace the battery this morning and the light is still on last week when driving the truck with a friend we smelled something terrible found out it was the 80amp fuse under the hood, replaced it and now I’m wondering if the alternator is the problem? Sidenote neither one of these lights were on prior to the battery needing replaced and or the fuse burning up any information would be helpful thanks guys
Check your wiring for shorts to ground, read posts above, and read my post "How charging System Works"
Have been following this thread - and similar for some time - but have a basic question. The various shop manuals (Chilton's, etc) show the attached typical schematic. Cannot understand the refences of off pages numbers, letters ( see yellow circles). Do not seem to be page numbers, section numbers, or picture numbers (?)
Have been following this thread - and similar for some time - but have a basic question. The various shop manuals (Chilton's, etc) show the attached typical schematic. Cannot understand the refences of off pages numbers, letters ( see yellow circles). Do not seem to be page numbers, section numbers, or picture numbers (?)
(2-2) means that is connected to wire/part on page 2 of the long page of actual printed FSM, under column 2.
Toyota electrical engineers back in those days were not as brilliant as its mechanical engineers. The charging circuit uses THREE fuses!
1) Engine fuse to excite the alt3rnator field,
2) Ignition fuse to power positive side of the charge fault light (and other dash indicators),
3) "Charge" fuse to connect negative side of charge fault light to "L" pin of alt3rnator.
Last edited by RAD4Runner; 05-03-2021 at 09:08 AM.
05-09-2017, 12:45 PM
