Hi, my 94 is dead. My wife took it out for about 10 miles yesterday, started as usual, but she noticed the gauges not working while she was driving, this morning the batteries seem completely dead and there is nothing at all at the key. Could the alternator go that quickly, and will it run if so? Where to start looking? Is it worth charging the batter
ies and try a start? Thanks FMK

 

If you charged the battery and started it you could test the alternator without removing it.

 

Update, charged batteries to about 13v, hooked them up, they lit the dash light briefly but now seem dead again. Its **** cold out and it was a brief charge, but could it be a serious short? I'm hopeless with electricity, please help! Thanks FMK

 

You need new batteries?

Please fill out your signature so we know what year truck you have.

 

check the grounds to the batteries, if they at all corroded, take them off and clean both ends. Coat with di-electric grease and re assemble. Then do the same for the positives. you can test output of the alt by checking with a voltmeter between the alt output stud and ground with truck running. Sounds like the alt went and she drove home on the reserve in the batts.... good luck Chris

 

Strange things happen when a wife drives your truck . Always start out by charging the batteries. You can not do an accurate test with low batts. Get a cranking voltage, should be 10.5 or higher, then get a running voltage, at around 1200 rpm. I like to see 14.5V, but can be 13.9 to 15 V. Make sure the cable connections on the batts are clean. Do all these things first and tell us the results so we can guide you to the next step. Good luck

PS; Charge batts on slow charge for several hours before testing.

 

Thanks for your responses, I did a slow charge and got the truck started. Voltmeter is reading high 15+ V. The first time I started the truck it held steady at that high value as I idled for about 5 min., the next time I started it a few minutes later it did the usual varying it does at start up. A couple of questions, is the output stud on the alt. the one with the largest wire leaving it? Where do I measure cranking voltage? At least now I know I can start it, and I moved it into the shop. We,re getting a blizzard with 2 feet of snow so I'll be busy the next couple of days. I guess then I'll try to test alt. output and maybe remove it to get it looked at. Any and all info is appreciated. Cheers FMK

 

"My wife took it out for about 10 miles yesterday, started as usual, but she noticed the gauges not working while she was driving, this morning the batteries seem completely dead and there is nothing at all at the key."

After this you slow-charged the batts and it started OK. It appears that you had a short which disabled the gauges and drained the batteries overnight. Better find it.

 

Are you useing a DVOM to check voltages? To check the cranking volts, hook up your DVOM to the left battery, unplug the shutdown sol, and crank the eng for 10 to 15 sec and watch the volts. It should not drop below 10.5 volts and recover above 12.0 volts quickly.
If the charging volts are 15 V, the alt is working. Turn on the lights, heater fan on hi, A/C on, and check the volts, above 13.5 everything is fine, below 13.5 check for slipping belt, burnt or loose wires, loose ground on alt field block, corroded connections to batt, or do an output test on the alt. Check the body grounds too, the volt reg is in the computer and needs a good volt source and ground.

 

I'm using a volt meter, but we recieved the weather that was predicted so no time to mess with the truck today, when I put the truck inside I pulled the batt. terminals in case it was a dead short. Thanks again for your help, great forum, this was my first visit.