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Pontiac Repair/No low beams AND Reduced Engine Power message


QUESTION: I have a 2007 Grand Prix Base. Last summer I was driving in rain and lost acceleration, display read 'Reduced Engine Power'. Check engine light was in so I took it to Autozone for free diagnostics. Pedal Accelerator Sensor (I believe was the proper name) was the code that showed up. Replaced it and everything was fine for 4-5 months when the same thing happened. Replace that one with a new one and all was again.
A month ago my high beams would turn on when I initiated the right turn signal, but only when the weather was below freezing. I lived with it until this week. I parked my car for 10 minutes. When I started the car back-up no low beams. Parking lights, fog lights, signals, high beam all work but no low beams. Its the already dark out so I drove to a gas station to look at fuses. All look fine with no issues. I start the car again to find that not only do the low beams still not work but the Reduced Engine Power display is back.
I go to a nearby AutoZone that was open and they diagnose the same thing with the pedal but  no help with the lights.
Today I went to an O'Reillys for a second look at the codes. Error codes are: U0107; P1125; and P2138. As far as solutions with the lights still no ideas. I dont know how to check the headlight relay without just replacing. Any suggestions?
One final note - in November one of the caps on the battery came off and may have lost some water. I just put the cap back on and continued using as its had no trouble starting.

ANSWER: Hi kevin:

well, the APP (gas pedal) codes are a frustrating code on these cars I'm sure it's not a pedal (again) is either a wiring issue or the engine control module. you noted that happens when it's wet out. there an eletrical connector on the l/f strut tower on that car depending on the model year the connetor is either round or rectangle ther are a ciuple on that tower. the connetor has the wiring in it for the pedal it's possable that ther is water/ corrosion in that connetor. unplug it and check for evidence of either in the connetor. if not there then ther could be other places that the wiring is an issue but way to many places to mention I have seen it where the harness comes out of the inside of the air cleaner the wires rub on the air cleaner housing. As for the head lamps sounds like the auto head lamp control module is bad. It actually looks like a relay but it's called a auto lamp module. it's in the right hand under hood fuse box. open the lid and look at the road map on the in side of the relay center it will be labled lamps or head lamps or auto lamps DRL something like that. ever year is a bit different. Good luck :-)

---------- FOLLOW-UP ----------

QUESTION: Thank you. I checked the 2 connectors on the l/f strut. All looked well so I reconnected and left as is. Check engine has not been on today so I'm putting that on the backburner for now. Headlights - I had a freind turn on and off the lights manually while I listened to the relay in the underhood fuse box. There was no click so I replaced. Headlights still don't work and relay still doesn't click. I can however hear the click of, what I believe is the relay on, the BCM for low beams on the passenger side. Am I correct that this is it? If so, and the relay is working correctly, that the issue would lie somewhere between the BCM and the underhood fuse box. Thank you for any feedback you can provide.

you could be right. the software that all experts has I can't cut and paste the diagnstic info in and it look right sorry. 9 times out of 10 that module is  the issue and nothing else. the other 10% is a switch bcm or wiring and no set pattern. I know that doesn't help you out but  being on the other side of the net doesn't help because I can't see what you have going on there.  in low light conditions the BCM takes over and triggers that module to turn on the lights so it really doesn't need the head lamp swictc input per say. Also with out a scan tool it makes it hard as well with a scanner you can look at all the BCM dats the inputs it sees and what it's trying to control (module) for the lamps. stuff like this really isn't very DIY friendly.

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Todd Puccio


General auto repair,electrical issues,driveability issues,anti-lock brakes,SIR systems,HVAC,engine performance,Gm specific. I have worked at my current dealership since the 1990 model year anything much older than that I have limited exposure to. I do not have very much transmission experience so those question you may want to ask of another expert. When you send me a question let me know the exact make/model/engine and year for the car or suv you have it makes it easier to answer the questions that way. If your happy with the answer I gave you please feel free to Donate. This is a free service to you and I am not compensated at all by this web site. I have 22 years of experience to share with you and my knowledge wasn't free to me. I had to pay for my education.


Experience in the area: I have been a technician in GM dealerships for over 22 years and I am a ASE master technician. I work at a Buick and GMC truck store Previously I worked at a Pontiac GMC store for 18 years. I Served a a lead technician when dealership was on a team system. I just recently moved to a Buick,Hummer,Saab Store when my franchise was purchased by this dealership. Organizations: ASE master technician


Education/Credentials:High school diploma,2 year vocational school degree 2 year college degree. Associates degree in applied sciences (auto technology)Awards and Honors: GMC master technician

Awards and Honors
Master GMC truck technician Master ASE technician in 9 categories

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