Volt guage

[michaela8456]

My volt guage is showing neg charge just under 12 with just the motor running bought new gm one wire alternator new battery tested gauge is working properly in my pick up but put in cobra showing under 12 what could be wrong please help.

[Velox]

Apparently your alternator is not active or functional. Some of the single wire alternators have to reach a certain RPM before they activate, I think something like 1500RPM or so. Rev up your engine and see if the volts go up to 14 or so. If not I would suspect a defective alternator. Just to double check get a voltmeter and test voltage directly at the alternator hot post with the engine running above 1500RPM. If that doesn't get you at or above 14V then the problem is the alternator IMHO If there is 14V at the alternator but not at your dash voltmeter then there is a glitch in the wiring setup from the new alternator to your main 12V harness - bad link, relay off, fuse etc. Good luck, let us know what you find!

[michaela8456]

revingm it up doesn't make it work.

[Velox]

Seems like your new alternator is defective You probably need to get back with whoever sold it to you, have it checked out, and replaced

[wtm442]

Check voltage at the battery with a good voltmeter. The small gauge may be bad ... but its most likely that you wired it wrong or its defective.

[CHANMADD]

With the motor running,disconnect the negative terminal on the battery.If it dies the alternator is no good,if it continues running it's the guage.