Engine dies

[67gmcss2]

My truck dies when I unhook the battery. it's 67 gmc if that helps. have had the alternator checked at two places- autozone and advance - checks out fine. truck runs with a new battery (figure it's draining it as we speak). runs fine with jumper cables hooked to another vehicle prior to battery change, but the minute you unhook the battery cable it will die within seconds. any suggestions on where my first place to check is for problem? all lights, electrical, etc. seems to be functioning fine until it dies. thanks in advance for any help.

[Wrcampbell]

If alternator is charging. Check your wiring harness. Something isnt connected correctly or wire broke. do you have a internal regulated alternator or regulator on radiator support?

[67gmcss2]

regulator is on radiator support...

[Wrcampbell]

The regulator may be bad. It controls the alternator. Do you have a volt meter. If so while engine running test voltage at battery and then at main main at alternator. A alternator should put 13.4-14.5 volts when charging properly. Without seeing your harness and checking your connections,I would have to try a voltage regulator, i dont know if anyone in your area has the know how to test it. But anyhow i would start with that. see if you can find one or borrow one that works and try that first.

The system is a very simple system. Check all your grounds and all fuses. Look for any cracked wires or broken connectors. Good Luck!!!

[67gmcss2]

thank you wrcampbell. I don't have a voltmeter, but will see if any friends have one that I can borrow and try that route (or borrow a voltage regulator too) and see if it changes anything.

[davepl]

Remember when testing with alternate regulator that it might need to be grounded (I forget). Don't just hook up the connector.