Zero Data

It does not appear too. I'm just at a loss as to why it works as intended when the engine is cold. Once the engine warms up, if you turn it of and start it back up, no charging unless you disconnect the exciter wire.

17 minutes ago, JFP in PA said:

 

OK, try this: If you turn the key on without actually starting the motor, and there is no battery light on the dash, the alternator has a bad ignitor and is bad.  It would not be the first time I saw a defective alternator right out of the box.  Fortunately, there's a definitive test for this as well:

1) disconnect the ignitor wire from the alternator and ground the wire
2) turn the key to on... ALT light in the cluster should come on

If it does... the cluster and wiring are OK and the alternator is defective.

If it doesn't... there's an issue with the cluster and/or the wiring to the alternator, preventing the alternator from exciting and thus delivering current.

 

You could also take the new alternator to an auto parts store that has a test rig and check it there.

 

Good luck.

 I'm a little lost on the instructions. My wife 06 Cayenne has a voltage gauge and not a battery light.

I replaced the alternator and have the same issue going on. Once the engine is warm, the alternator does not output unless the exciter wire is disconnected.

Had the battery/generator light come on. Check battery, had voltage but couldn't take a load, I replaced it. When the engine is cold the alternator will put out 14.2 volts. Once the engine has warmed up, if you shut it off and restart it, no output from the alternator only battery voltage. I checked this at the back of the alternator to make sure this wasn't a grounding or started Y cable issue. I noticed that if I unplug the exciter wire, I get 14.2 volts regardless of the engine state, cold or hot. I checked the voltage at the exciter wire and was receiving 12v when the engine was running. If I plug the exciter wire back up with the engine running and the alternator providing 14.2 volts, I see no change until I restart the vehicle. Once I do that, I'm back to no alternator output, until I disconnect the exciter wire. I'm trying to determine if I need to replace the alternator or if I may have a larger issue looming.

It is a 2006 Cayenne S.

Thanks,

Scott