Alt electrical problem

[USA69Z]

Guys , im having a headache with my truck electrics.. my battery died the other day (3 months old) so i replaced it under warranty and thought my alternator was faulty.. so i replaced it ,, so i have a new battery and alternator fitted and under a test it isnt charging? so i took the truck to an auto electrician and they bench tested it and it came in at 14volts? so i have re fitted and it dosn't charge when fitted .? is there something i can check? 3 wire hookup.. 1 big red wire to post and a brown to 'f' (field) and pinky red to 'r' .. does the charge light on the dash have anything to do with the charging circut? or any ideas?

1970 - i have a int reg alt and wired to suit. hei dissy ..

thanx, Gav

[Wrenchbender Ret]

Unplug the connector & turn on the ign. switch. Use a test light. All the wires should be hot. The brown wire will glow just slightly. It feeds off the gen. ind light. If the bulb is burned out or there is a problem with the dash connector it will not work.

[GMCJOE]

Did you do the wire snip conversion and connection at the old external regulator? If not, I would check the wires where that is present. May have come disconnected.

[GMCJOE]

What I am asking is did you do the conversion yourself when you put the internally regulated alternator on? And if so, did you do the wire snip and connect the 2 wires at the old external regulator?

I did this on my truck after installing the internally regulated alternator and the connector plug came out of the external regulator a week later. So, I would check there to make sure everything is still connected (if that is how it was converted). If the external regulator is still present, it might have went bad. I would also check your fuses. If that isn't the issue, you will have to get a wiring diagram and start tracing the wires with Coloring Pencils as to how the electricity flows. Then check the wires for breaks, and the components with in.

[USA69Z]

ok , got it to the shop today and he re-tested the alt,, its fine at 14 volts.,, he can only find that the fan belt needed tightening,, im not convinced.. funny thing is when you turn ign the brake warning light comes on and goes off when the engine starts up.. no other light comes on with the ign switched..he said he removed the dash and all checked out ok..ive ruined 2 new batterys and replaced the alt so far ...

[FrankieD]

Check out this thread

http://67-72chevytrucks.com/vboard/s...=351093&page=2

[GMCJOE]

I am not sure how your conversion was done. But this is how I did mine (link provided). If it was done this way, I would check over the work. If the external regulator is still present, it might have went bad.

http://67-72chevytrucks.com/vboard/s...d.php?t=119379

[Wrenchbender Ret]

If it is charging 14 volts in the truck, it is working OK. Its true a loose belt will cause it not to charge, especially on a 6 cyl. You didn't say what year or engine it is. Sounds like the bulbs are in the wrong hole on the dash unless it is a printed circuit. In that case it may be a wireing problem.

[Xeen]

Either the conversion is done incorrectly or you have a serious energy vampire somewhere.
If it were me I would start going through ALL external wiring, the engine harness, headlight harness, parking lamps, side marker lamps front and back, main intermediate harness and rear harness. If you go through everything and visualy inspect it and find nothing you need to start doing a resistance check on all wiring one wire at a time untill you find the problem.
Are any of your external lights dim?
Do you have all of your ground straps on the truck?
Go through this methodicaly and you will find it.
Check to see if your kid put a dime in your cigarette lighter sleeve (its no laughing matter its happened before) but LOL
Anyway keep us up to date.

[GMCJOE]

Any updates on your issue?