1997 Isuzu rodeo V6 3.2 5 speed

I have a 1997 isuzu rodeo v6 3.2L 5speed that has an electrical problem that I can not figure out. at Idle and parking lights off the volt gauge reads about 14 volts (normal) but once i rev the engine the gauge drops to 12V and in stop and go traffic the battery and brake lights on the dash flash on and off. BUT…if I turn my parking lights on the volt gauge will stay at a constant 14V. no other load (fan, AC, radio, flash of Highbeam) will keep the gauge from dropping to 12V. only the parking lights make the problem seem to go away. I’ve replaced the alternator cleaned all the ground points from alt and battery. I even replaced the ECU from a salvage yard. Could it be another bad ECU or a different problem that I’ve over looked?. HELP! any ideas? thanks

I’m having the same problem. Everything was working fine, I started noticing the brake and battery lights coming on like the engine was stalling. I’ve done some research and my guess is that the alternator or voltage regulator is not working. I’ll take the alternator to be checked tomorrow. Did you fix yours?

Did you ever resolve the problem? My alternator went out this year. Replaced it 3 times - twice myself and once with my mechanic who thought it was the ECU. Went to authorized Isuzu dealer who went through the whole check again. Said it must be the ECU. Had them order Isuzu ECU that they put in. No change - when I accelerate the alternator stops charging and does not return to charging as it should. I must release the accelerator and coast 3-5 seconds until I see the charging resume. Then carefully if I gently press the accelerator I can maintain the speed. Isuzu says that is normal. They then said compare my car to another - do you know how many Isuzus get repaired at the authorized dealer - none but mine. Great idea Isuzu except no other Rodeo to check against. I suspect the real issue goes back to rebuilt alternators. If that was your solution please let me know. By the way only after they put it in did they tell me that the ECU was not returnable. In DISCUSSIONS with them now about not being informed of this $$$$ fact since I found the exact ECU for my Rodeo version at a recycle yard for 1/10th the cost. Too bad, car is otherwise top shape. I can drive it now if I watch how I accelerate and play with the pedal when it discharges.

Found a work around - turn on the headlights seems to override the computer program to shut down the alternator. With that I will drive this until it D-I-E-S.