2003 Cobra charging after new alternator install

[Dave.O]

Took the 2003 cobra out of storage and noticed the alternator was not charging.
Prior to starting the car, hooked up a charger to ensure full battery.
Started driving the 40 min home and noticed 11.5 volts on aero force gauges, later confirmed 11.3V at idle with multimeter. Recharged the battery, swapped out the alternator for a rebuilt OEM I had on the shelf still only charging 11.7 at idle.
drove the car to get to operating temp, now only charging 11.3v.

battery charged engine off 12.5v, start car immediately drops to 11.7, rev engine to engage regulator, no change

checked the power distribution block, 20A fuse in spot 20 was not burned out

prior to swapping the alternator again (and having to buy a new one) what else should be checked?

thanks

 

[01yellercobra]

How are the grounds?

You could take the alternator that's out by a parts place and have it tested.

 

[Dave.O]

Grounds appeared good


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[01yellercobra]

I would get the alternator you have out tested. See if it's really bad. If it is then there's a good chance the one in your car is bad. Maybe pull the battery and have it load tested out of the car.

 

[03' White Snake]

Check the connections on the alternator. Sounds like it’s not turning on. Depending on what aftermarket alternator you are running you need to jump the power wire to the 12v signal in the alternator harness.

 

[03cobra#2]

I had a similar issue. The plastic connector was not snapped in all the way.

 

[Dave.O]

I did check the connection for tight

I’m wondering if the pigtail might be broken


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[hotcobra03]

Ground?

Have you tried meter ground on engine vs battery..to see if 14 volts output is happening

 

[Dave.O]

Ground?

Have you tried meter ground on engine vs battery..to see if 14 volts output is happening

I have not but will try


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[03' White Snake]

Unplug the alternator connector. 1 wire is 12v hot all the time, next wire is hot with key on. Check with a multimeter. Alternator needs power to make power. If both of these wires are not 12v with key on, then the alternator is not going to produce power.

Also check ground from case to frame with multimeter. It only gets grounded by the mounting brackets. I added a secondary ground wire on mine. I powder coated all the brackets and timing cover and was having issues. Cleaned all the mounting locations and added a secondary ground wire and it fixed the problem.