Alternator???

[samw]

If you are getting 12v at idle, I wonder if there could be a issue with the throttle positioning sensor not having the correct voltage? Just throwing that out there. If at idle all is good then you go past the good point and the sensor loose's it's proper voltage then it would in turn cause it to go in limp mode correct??

[CP3]

well the alternator might be bad after all because the batteries read 13v and the alt 12v.
I have a throttle cable so Im still not sure how its even in limp mode unless the computer is just that good....

[R&T Babich]

OK I checked out the alternator at idle (cuz thats all I can do) and it still looks like its putting out 12v. ...

The batteries should read around 12.5v with the engine off. The voltage should read around 13.5v (or higher if more charging is needed) with the engine/alternator running, but at an rpm a little above idle. The older mechanical voltage regulators wouldn't kick in until around 1,000 rpm and the modern electronic regulators will start around 750-850 rpm. If you're idling at 650-750 rpm the regulator may not have kicked in, yet, and the voltage would be battery voltage.
Check out this info: http://www.bcae1.com/charging.htm

[chpthril]

On our last conversation, CP3 was going to round up a battery charger to get the system voltage over 13v and fool the ECM into thinking the alt is charging, to see if it will come out of limp-mode.