2004 s-type alternator problem -please help
 

I have a 2004 s-type v6 automatic transmission. I recently got an odb-II error p1245 and p1111. I looked these up and got the following: P1245 Alternator Load Input Failed Low and P1111 Intake Air Temperature (IAT) Sensor Circuit Intermittent High Voltage. not

I had the alternator replaced, but not with an OEM alternator which is a Denso 2R8310300AB. I replaced it with a supposedly comparible Duralast model. After replacing, the battery light is on, which states that there is an alternator or battery problem. I replaced the alternator with another Duralast alternator that is giving the same battery light error. I had the battery and alternator tested as well as putting a volt meter on it my self which read 12.3 volts (engine off) and 13.9 (engine on) across the negative and positive battery posts.

I suspect that the replacement alternator is causing the battery light error and not the wiring harness that attaches to the alternator because it is not OEM. Has anyone possibly had this issue?

SGB, first, using a multimeter, confirm a bad output from the alternator by measuring the voltage across the battery. If the alternator is functioning properly, you should be getting a voltage between 13.8 and 14.4 VDC. If you are getting this voltage, then let me know and we will take actions from that point.

If you don't get 12 VDC on the white/red wire, then that is indicating a bad wire between the alternator and the ECM (engine control module) or a bad ECM.

If your voltage is down around 12.5 VDC, then that is confirming the alternator is not functioning at all. Next, get access to the alternator and find the green/orange wire and see if you have 12 VDC on that wire with the motor running. If no, then check fuse F15 (5 amp). If you even think the fuse could be bad, replace with a new fuse. If yes, then you have confirmed that fuse F15 is good. Next, measure the voltage on the white/red wire going to the alternator. Are you getting something very close to 12 VDC? if yes, then this is confirming a bad alternator or you have an issue with the wire running between the alternator output and the starter. You can confirm between the two by measuring the voltage on the output of the alternator. If you get 14.4 VDC (or something near), the alternator is good and the wire is bad, you get something under 13.8 VDC, bad alternator.

That should hopefully get you down to the point of finding a bad component and being able to fix it. Please note that the battery should be recharged before connecting up the new alternator as the alternator can be overloaded and be damaged if you initially attempt to run the car with a drained battery.