I have a 93 f150 4.9L. I replaced the clutch and i don't know what happened but the battery died. I tried to jump it but it wouldn't hold a charge and when I took a jumper cable off it would die. I assumed the alternator. So i took the alternator to the parts store and had it tested. I came out good so I bought a new battery, it was time anyway. So i put the new battery in, alternator back in and checked the terminals, battery cables...all the usual suspects. Well, it was still draining the battery, so i went back to the parts store and retested the alternator like 6-7 times, all results the same-good alternator. So I had them run a battery test out on the truck. Came back no voltage. So I pulled the wiring harness for the alternator. One of the plugs was burnt so I replaced it. Also, one of the plugs has 3 wires coming out and turning into 1 wire that connects to the solenoid on the firewall was frayed and fell apart upon removal. Replaced that as well. put it back together and the indicator would stay on the low end of normal while idling but would drain slowly while driving. I read on another thread here that someone put a jumper wire from the red/green wire (runs from ignition to battery indicator) to the green/red wire (runs from battery indicator to alternator). I pulled the instrument panel out and found the 2 wires in with the plug that attaches behind the oil pressure and water temp gauges. I would jump the wires but i dont want to mess anything else up since they aren't in the plug behind the battery indicator. So, if these are the right wires and/or if there are any other solutions to try, they would be greatly appreciated. Everyone says to give up on her but she's my baby and I would like to get her working again. Thanks in advance.

 

That alternator with the burnt-up wires is the old-school second-generation (2G) alternator that is known to catch fire in exactly that way. Search on here and you'll see some posts from others that have had that bad girl burn up on them. A common upgrade is to replace it with a 3G alternator, which is not as prone to catching fire, and you can get one with a higher output rating too. I'd replace it before doing much else. It's already tried to burn your truck up once, so I wouldn't trust it any further... especially if it still ain't working.

As for jumpering the charge warning light, on every Ford I've worked on there is a resistor (forgot the rating, 500 ohm?) in parallel with the lamp. This is the exciter circuit to the alternator/regulator, and if the lamp were to burn out the resistor would keep the system charging. I don't know what would happen if you jumpered it, but I wouldn't try it without at least looking at a schematic or talking to someone that has had it done for awhile without problems.

 

I myself have done the generation3 upgrade on my 87 it had a 40 amp alternator which is barely enough to run the heater motor on high. I have a meyers snowplow which is a pretty high demand on an electrical system but the 130 amp G3 is a wonderful unit. I went to my local auto electrical motor guy he assembled it while I waited and gave me the harness splice wires my voltmeter runs nomally at about 14.2 at idle. And no problems running the plow at all while wipers and heater motor heated mirrors and other accesories. Best upgrade I made so far i think