Hi guys I was wondering if I could get some help. I changed my alt well I got 3 b4 got good one put it on n light stayed off for a day. I bought a new voltage regulator light is still on and only running at like 12.5 volts. I changed fuses, but I noticed two white connectors under dash next to fuse box could one of those went out? Any help would be appreciated thanks

 

I say this because when I turn on lights, interior, radio, and heater its running same voltage. I dont know the name of the two white connectors but sure one of them could be culpret.

 

Check under your hood at the starter solinoid for any broken connections thats what ended up being the problem on mine. Take a voltage checker and hook it up to your battery with the truck running. I believe at idle it should be atleast 13 volts. Rev the truck up the voltage should increase. If it doesn't take the voltage regulater and check the alternator to make sure its getting power.

 

I appreciate the comment I have replaced all those wires underhood I was wondering if it could be the ignition switch causing it to stay on?I noticed that there is a wire coming from voltage regulator to the ignition switch under there. I think thats the name of one of the connectors beside the fuse box n other is instrument switch could these be a problem if never replaced?

 

I'm not for sure on the ignition switch. Nummerdummy feel free to time in. But have you check the fuses that are on the wires under the hood? New stuff can go bad quick. Also have you tried the voltage checker at idle and rev? It will really help you pinpoint the problem.

 

WOw I didnt know that there were fuses in the wires under hood I will sure check that doubt they ever been replaced. I dont mean to get on nerves I am new to mechanicing, how many fuses are on wires under hood and where located if you have time to consult.

 

1979 f150 302
tougher than nails

 

Make sure the fusible link between the alternator and the battery is still intact. All the ignition switch does is route 12 volts to the voltage regulator with the key in RUN. You can make sure this is fine by removing the connector to the voltage regulator and turning the key to RUN. You should have 12 volts at the I terminal of the regulator plug. If that's the case, then everything past the firewall is out of the equation.

 

Thanks I unplugged the regulator and checdk the connector it was running 12v, but if I check the back or alternator its reading like 12.3volts. Could it be a bad diode in alt? I have went thru one battery already and this one wont last long if not charging. I checked for a fuseable link I am new to mechanicing but will continue searching. But from starter relay to back of alt I think it is, only showing 12 volts too. So I think Advance gave me a bad alternator.

 

Well I think my problem may be more serious than I thought, I forgot to mention the heater only works sometimes like there is a short or something. I am wondering if the wiring from fuse box to heater is connecting somewhere. I checked fuses and they are fine and getting juice when checking them. I am stumped on it I guess I will start tracing it, maybe thats where the other 3volts are going from the alternator. The battery doesnt get drained over night, just the alternator isnt putting out a charge and its the 3rd one I have traded in so far. Any help would be appreciated guys if anyone has had similar problems with 1979 f150 302 2bbl. I check the back of the alternator and its only putting out 12.3 volts same as whats showing on battery posts when running. When engine is shut off then shows 12.6 volts I am lost. Would faulty wires cause all that? From what I can see the wires are all intact and no breaks or corrosion, also I added another ground from alternator to fender and from there to chassis just to make sure and connecting block also just incase.

 

If the alternator, VR and fusible links check ok and yet the idiot light in ON, the "shunt" is burned out.

Josh

 

well the light isnt on anymore but still not charging I am going to hit it early in the morning goes some valve cover gaskets and manifold gaskets to put on. So I will have my nose all in it trying to check out everything. I havent seen any fusable links unless thats the two sqaure plugs that connect that look outdated but I pulled them apart n looked on inside and no corrosion or anything that looked remotely bad. I have been trying to find pics of where fusable links are on 1979 f150 still lookin if u cant post some would be much appreciated. Also I have no idea what a "Shunt" could be, in depth explainations maybe be needed lol. But I will start my adventure in the morning and hopefully will come some good news from everyones replies.

 

Unless the light has now also burned out...

Fusible link is highlighted in this pic:



You have to test for voltage in various spots along the length of the wire, sometimes you can tell if it has blown if it feels soft, but other times you can't.

Josh

 

OK well I think ur pic shows me my problem, that fusable link goes to back of alternator right? Mine isnt like that at all and from back of alt the is only 12.2 volts pumping out at all times when idle or at 1200 rpm or higher. I am going to Advance to purchase a fusable link and connect it as it looks on your pic. I apprecaite the help and hope that sums up my problem. If any other suggestions I would appreciate. Like I said before I unplugged the voltage regulator and checked the connecter and sure enough there is 12v going to it so I guess that rules out Ignition switch. I am just stumped on it.

 

Thanks for the photo that helped me alot, I went out todau and took all the wores off the alternator and looked for this one. Evidently the guy that had truck b4 me tried to rig the alternator with some kind weird fuse thing. I took it loose from the starter relay and it had a wire connected to it going to voltage regulator. I had to ride 30 mile to another advance one county over cause was only place that had one. But when I got back I connected it to a 12 ga wire out of the end and then connected another 16 ga wire between that. Bam its done and without you guys I would been stumped forever. It now puts out 13.8 volts idle. If anyone has a photo of their carburetor vacuum lines I owuld appreciate that. Cause guess thats my next job, the egr and other stuff isnt connected. Alot of lines on carb arent connected just plugged. Photos of anyones carb would be appreciated so I can connect thanks.