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"Reduced Engine Power" message

T

TomDaBomb2u

New member
Hello All,

I have a 2004 Grand Prix GT with about 102k miles on it. Last week, I got in, turned the key, and all the lights blinked on for a split second, then the car went completely dead. I got out my multimeter and tested the battery, and only got like 3 volts. I cleaned the terminals, and it started OK. I figured that was the end of it.

Tonight, I was driving, and the my radio lost audio (all of my speakers are amplified). I turned the car off, and it did the same thing as before: all the lights blinked, as if it were about to turn on, then went completely dead. I wiggled the battery cable, and I got electrical power back, but the engine wouldn't turn over. I saw a message that said "Starting disabled due to theft system." I did a full ignition cycle and tried again. This time it worked. Now I have a message that says "Reduced Engine Power."

I've read that 30 minutes or 3 ign cycles without a diagnostic failure will clear the message. It's been about a half hour. I'm about to go try it now and see what happens. . . .
 


yeah. . . it's still on. No noticeable decrease in engine power though. I've deduced that my battery probably needs replacing (i.e amps dying, car starting after I jiggled the cable), but that still doesn't explain the Reduced Engine Power message.

Any suggestions?
 
Cool. Thanks for the reply. I went to AutoZone and had them read the OBD. It said the battery as well. I'll have the alternator tested too.

Thanks again!
 
Uh oh....the problem has escalated. Earlier today it started showing "Charging System Failure" and weird stuff started happening.

1. My low fuel message is on, but I have over 1/2 tank of gas
2. My blinker indicator flashes inconsistently
3. The computer continuously reboots. (Grand Prix logo shows, then a line of dashes, repeat)

I'm starting to think it's not the batery, but an alternator connection, or the alternator itself...any more suggestions folks???

Thanks,
Thomas


Edit: alternator tested fine. Confused. . . I'm about to clean (and possibly replace) my battery terminals to see if that helps
 
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the battery being dead means that the alternator is doing all the work to keep the car running. without a good battery youre killing the alternator.
 


Bio248 said:
the battery being dead means that the alternator is doing all the work to keep the car running. without a good battery youre killing the alternator.
Click to expand...

Any time the car is running the alternator is what does the work to run the car, not the battery. The reason a dead battery will kill an alternator is because of the extra load the battery places on the alternator as it tries to charge up.

You can take the battery out of a running car and it doesn't care. It's not a load so it doesn't hurt the alternator, and it's not doing anything useful. It just sits there idle until it is needed (like when cranking, or running accessories or something when the engine isn't on).
 
Thanks guys. I tested the battery and alternator and they both came out fine. I understand the roles of both of them, and know how they interact, which is why I'm having a hard time diagnosing the issue. At this point, I'm leaning towards bad connections. Tomorrow I'm going to clean terminals, and replace wires as necessary.

Thanks for suggestions. Keep em coming!

Thomas
 
Yesterday, my IC stopped reading altogether (speedometer, fuel, temp, RPMs, etc). All went to 0 and my low fuel light came on. Remained like this over 2 IGN cycles. Now it works fine. Possible short in the harness behind the main center display maybe?
 
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