I got a 1980 yota 4x4 pickup with a 20r recently the alternator went out so we went to put in another from the store but the one we got was not good either so I took it back for another before I left I had it checked out and it checked bad as well so I went with a GM 10si alternator we rewired it so we could use it got the system charging again but lost the dash lights, brake lights, and marker lights. The fuses all checked out fine tried feeding it power through the socket for feed back and we got nothing. So is there a relay that is responsible for this that I am missing manuals for schematics are damn near immpossible to come by cant find them and when I do they want a fortune for them. The current wiring on the alternator is pin #1 is for the idiot light, pin #2 is for the power we hooked it directly to the same point the power wire to the battery was set up at except we re-routed it to the starter as well (not fond of hydrogen gases eating my connections) that is why we went low. It starts and it charges the headlights work hi and low beam but no dash, brake or marker lights. We completely eliminated the external regulator. Not sure what else to tell you we have a hot wired the current lights for a quick fix but we are looking to find out why them three lights stopped working. Just thought you all may have some insight or ideas why. Thanks

problem fixed GM alternator is performing beautiful

Cool; do you have the part number for the alternator; still using the stock voltage regulator, or no?

I live about 26 miles from the nearest NAPA, so batteries, starters, and alternators I have those guys check before I even leave the store. <img src="/forums/images/graemlins/cheers.gif" alt="" />

So what was the fix to the problem?

Communication error was the problem, my dad who was helping me do the electrical thought that I said that I had lost all lights exterior and interior minus the head lights no markers brakes, dash lights and with that the original harness that went to the alternator was set aside so when that it was communicated that we should try it with the old harness he said I thought you said that it didnt work I said no it does work at least it did before the old alternator died so we pluged in the original harness and started the splicing there and works great I had problems with some H-4 head lights that I had bought a while but the problem I had with them not being bright and in later thinking I am thinking the original alternator could not keep up with them and may have led to the demise of it. Now it is not a problem at all I would reccommend that if you have not changed to a GM 10si alternator that you do so.

(sorry no part number)the generator that I used is used on a 1980 Pontiac Bonneville with a 350 engine it is a 10si GM alternator the only one that is as common as the 10si is the 12si these parts are common and they are used for multiple applications tractors, industrial machines, etc. As for the external alternator no I did not use it this one has one inside so we bypassed it. if you want to know what we did pm me and I will send pictures of it. with descriptions the difference being is that we moved it from the bottom left to the upper right we went from 55 amps to 63 amps. GM did make this alternator right it was used from 1973-1993 Bottom line it is reliabe most parts houses have them is works better than the old one EVER did