how do I test the ecu for charging system?

[dahawkster]

OK so my car after it warms up seems to be running at just around 12.4 volts my battery and alternator test ok and I replaced the alternator anyways since I had it off already. I'm starting to think its the ecu, can somebody please tell me exactly how to test it? And I read on one thread I can disconnect pin33 one the ecu and it should go back up if the ecu is bad, can anybody verify this for me please and will that cause any other problems like a battery light? Thanks

 

[luv2rallye]

No, pin 33 is normally floated high by the ECU. When it is grounded (by the ECU) the alt is forced to 12.5v max so engine can deliver more power to the wheels. But this is only when the engine is at WOT and under heavy electrical load. That line should normally not be at ground. If it is you need to find out why. The charging system is completely regulated by the alt, not the ECU (except for this one special pin 33 case).

Normal alt/battery test: http://www.dsmtuners.com/threads/car-died-on-freeway-electrical-problems.258035/#post-151165661