Charge light stays on the whole time

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Apr 8, 2019
The charge light stays on the whole time while driving and sometimes when I close and lock the truck. I replaced the alternator and the battery. The light still stays on. Some other forums have told me that its the ground wire under or near the battery. I cleaned and re-tighten the screw but the light still stays on. The only other ground/wire connecting to the chassis are 2, they connect to the radiator mounting bolts and the frame.

78 toyota hilux.
Theres probably a charge relay in that one that has died. Look near the steering column.
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I don't think this truck has a charge relay. I did not see anything in the wiring diagram connecting to a relay.
Have you tried checking the grounding of the regulator?
Where would the regular be placed? The manual does not talk much about this light.
On my '84 it was on the driver's fender liner. No idea on your vintage truck.
I’d spend an afternoon with a dremel & a brass or SS brush tip, pull all the terminals & polish with the dremel & toss whatever flavor grease you have handy in the hardware/terminals.

Dielectric if you’re buying grease for the job, but whatever will work.

I had a intermittent engine / fuel delivery problem that I chased for literally months on the old turbo truck, turned out there was a common ring terminal that had 3 grounds crimped that attached under the intake - it had a finger tight nut that caused many days and ~$2-300 in parts like fuel filter, pump, yadda.

If you do that you’re also just plain looking in spots you normally don’t- you never know the random stuff you’ll see that needs a little love.
I have found the regular pulled it apart and everything looks fine no corrosion nothing melted. Also noticed I don't have the ground wires that connect to the engine and frame. I got my engine mounts changed a few months after I bought the truck and I guess they forgot to put them back on. The electrical issues started way after that, like a 2 years afterwards so never thought to look at particular ground. @LINUS that is a great idea and I will do that this weekend. I will also be changing the ground wires form the batter to the frame and connect the missing engine ground. What cage wire should I use?
Ground the battery to the engine block, near the starter if possible. Engine to frame and engine to body grounds can be reasonably small, like 10 gage wire or equivalent flat braid.
I went through the whole truck and sanded, cleaned and greased up all grounds. Also installed grounds from engine to frame to which I was missing. Charge light still on. Has any one upgraded the voltage regulator?

I also noticed that when I slam the door closed the charge light comes on momentarily. When the engine is off. I never noticed till I was looking for it to come on this weekend.
I think that you need a wiring diagram specific to the truck. Find a Factory Service Manual if you can.
I think that you need a wiring diagram specific to the truck. Find a Factory Service Manual if you can.
Did i miss this someplace? What are you working on?

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