I have just acquired a 88 4runner 22re automatic that is pretty clear of rust. Had to do a little work to get her running, but it is running great. However I cannot get the alternator to charge. The charge light and the brake light ikn the dash do not burn at all (i have confirmed that they have good bulbs) I have checked all fuses and verified the grounds that I know about and all show good. I have a good connection between the output of the alternator and the positive side of the battery. I have 12V on one wire of the regulator connection with the switch turned to on, but nothing on any other wire. Shouldn't I also have 12V on the larger white wire on the regulator plug? Also my temp and fuel gauges are working off and on, more off though. Anyone got any suggestions of what to look for? I believe that the truck has had an engine swap out of a manual transmission 4runner. Any guidance that any one has would be greatly appreciated.

 

If you only have 12VDC at the alternator something is sure wrong.

Time to get yourself a copy of the Toyota Electrical wiring diagrams and work through things one circuit at a time.

Corroded or loose connections .

you have taken the grounds off and cleaned them?? Not just looked and called them good.

Fuses loose in sockets.

Then one never knows just what the last owners may have done.

 

I have 12 volts at other places. Most things on the truck work. I have a haynes service manual and one that I found online with 1500 pages of goodness. I have removed cleaned up and reattached all grounds under the hood and found one that was a little dirty under the hood, cleaned it up too.The issue is that none of them have much detail on the alternator circuit. The fuse panels look good also. On the alternator regulator plug, shouldn't there be constant voltage on the bigger white wire? If so I get nothing with it switched on or off. I have tracked the wire through the wiring harness until it appears to go into the top left corner of the dash. From there I have no clue where it goes. Anyone know about where this wire should connect?

 

Just how are you measuring your voltage??

The fully charged battery should be about 12 1/2 VDC

A running engine with the headlights and blower motor on high should be 13 to 14 VDC.

With the key on all 3 wires on the plug should be powered

your sure the charge fuse and the ignition fuse both 7.5 amps are good

the 15 amp engine fuse

those and the fusible link are all the protection in the charging circuit.

If you don`t have a Multi Meter now is time to get one.

 

I am checking with a digital multimeter. I am thinking that something bay be bad under the dash but I am not certain. I have started tracing wires and looks like the white one (the top of the regulator plug) runs through a couple of plugs and back into the underside of the dash on the drivers side. Does this sound right? My battery is fully charged and shows about 12.6V across it. With the truck running it only show 12.3 and the more stuff you turn on the less voltage that it shows. With the charge light not coming on and it not charging I am thinking that it would be a wiring issue. has any one has a similar issue and if so what did the fix wind up being?

 

The previous owner had done some custom wiring that made no sense at all. I don't know where they got it from but the head to total wrong harness plugged into the alternator. Looked in the old junk truck found the correct one wired up and I'm in business.

 

Glad you got it figured out!!

These is no telling what some people do to the wiring .