Toyota 8FGCU25, battery light on, new battery/alt/cables.

[SARuger]

My coworker that has been working on this truck is out of town on vacation so I inherited this thing for the week.

I have to go there today to sort it out.

New battery, new alternator, new cables. The battery light is still on.

Anyone have any idea where to look? My plan is to check the starter and see how far its drawing the battery down while cranking and then if I can run down our only diagnostic scanner, run a test to see what it is saying.

 

[Delmer]

Even if the battery is nearly dead, the battery light should go out as soon as the engine gets above idle speed. USUALLY the battery light is set by either low voltage, or the alternator is drawing amps not producing amps, you should have the manuals to figure that out.

Go right to the alternator with it idling, what is the voltage on the various wires, the big one will go directly to the battery +, and it will need a switched power usually. If the big wire to the alternator case is not 13+V then it's not producing power, if it is 13+ then where's the voltage dropping that it's not getting out?

It has new cables, but does the ground go the chassis or the engine, is the connection clean, and is the engine to chassis ground clean. Does the big alternator to battery wire have too much voltage drop? You can check all those things with a volt meter with the engine idling, bat light on, and all accessories running. If it has an external voltage regulator then you need to check that, never seen a Japanese external voltage regulator though...

 

[tool_king]

I have seen in these units where the positive cable hooks up there is fuse able link that might have a blown link or corroded .

 

[tool_king]

here is a manual on the 8 series
8FGU 15, 18, 20, 25, 30, 32
8FDU 15, 18, 20, 25, 30, 32
8FGCU 20, 25, 30, 32
It shows the wire hook ups and schematics.

 

[SARuger]

Thanks everyone. I did not get called up there today but I think I will before the week is out. The manual will be helpful! We have them at the shop but I can download that and carry my laptop. Maybe someday they will get me hooked up to the Toyota portal.

The wheels move sloooow