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Discussion Starter · #1 · (Edited)
Hello, alround 3 years ago I bought a 2004 Pontiac Grand Prix gtp comp g, with 87000 miles on it. It had one problem and that’s why the guy got rid of it, it has always stored code p1626 theft deterrent fuel enable signal lost. It had always lost the signal after it was running so all it ever did was throw a code. Also having that code it would make my cars instrument gauges act crazy! I could be driving fine all of a sudden I lose my areoforce interceptor gauges they go out first, then two seconds later all my instrument cluster goes to 0 gas,tach,Speedo, and coolant all show nothing but the end he never misses a beat and I’ve found pulling over and shutting the car off and opening the drivers door momentarily will reset everything start it back up and it’s as if nothing was wrong. Now it could be 2 miles further and it could do it again or it could be hundreds of miles, it’s went months without doing it and it’s also did it 3 times in one day.
so ive been living with that I tried to look at the ignition harnesses a while back never found it out, now more recently a few weeks back I went to drive it and the fuel pump didn’t prime, I looked and all my instrument cluster was already faulted out before it cranked, well that make the car fire up and die a few seconds later. I took the other car and the next day it ran like nothing was wrong. Now two weeks later I just drive it yesterday and parked it in my drive and now the fuel pump won’t prime at all so it just cranks. Also have service stabilitrak, traction control is off abs light is on and for the last 5 weeks the brake Light was on. That had went off but I got a code u1040 lost comms with brake control module. Not sure if that has anything to do with it. I also yesterday night pulled the body control module and everything looks great from there. I swapped it out and now it states starting disabled due to theft. Codes changed from p1626 to p1631 start enable signal not correct. I’m not sure if I should try therelearn with the BCM or if I should put my old one back in. I pulled the plugs on the bcm checked for anything pushed out pins or broken wires as far as I can tell nothing is wrong. I wouldn’t think it came from the factory like this.
also have p0171 system to lean that I’ve been fighting with ever since I changed it over to e-85. I bought used 150 siemens injectors, a aem e85 fuel pump, and I sent my computer to get tuned to e85 from zzp. Ever since I gotthe computer back it has always ran lean, like 15.4-16 sometimes 17 when cruising on my wideband, when under pedal it’s correct at 10.4 but when cruising or idling it’s running lean. I bought a smoke tester thought I fixed it when I found a vacuum leak but it’s still there. Ive checked everything on that to. Not sure if it’s tuning. Or if when I swapped the fuel pump from the assembly the aem pump had no venture port for sucking extra fuel from bottom of tank. I’m just stumped as to why the car won’t fire up now. Maybe it is the body control module. Just want to seethe Grand Prix gurus opinions! Thanks! Let me know if you need any more information.
Update I’ve been out working on it this morning, did the relearn on the body control module after relearning that it only stated service theft system, but was normal but no fuel pump prime so I assume it didn’t help as the problem is still apparent, then watching a YouTube vid of 07 GXP having similar issues jiggled the ignition back and forth from on to off and just like in the vid after 8 times back and forth I heard the fuel pump prime! Still with the other BCM, so I tried to fire it and still no start, grabbed either and it ran, so I’d assume it disabled the injectors. I’m swapping the BCM back to the old one doing the relearn now. Will update again soon.
Alright I got the old BCM back synced with the car, no more service theft system. Which I’d assume is because I didn’t have the key for the other BCM even if I relearned it. Anyways ever since I jiggled the ignition a bunch of times that’s what ultimately fixed it cause it’s now running again until it happens again. I never replaced the ignition because the previous owner stated he had tried that and that’s all he tried. Also when I had the ignition out and doing the relearn the pass key sensor fits in behind the plastic part of the ignition but through the plastic part I could feel heat from it just warm but nothing else is warm like that normally. In between the wires and the ring I guess you’d have to see the ignition to know. Anyways any guesses? Bad ignition switch or pass key sensor on the ignition? I couldn’t get the pass key sensor out. The ignition had two wire harnesses and a cable and the pass key harness I couldn’t get the pass key off. Anyways thanks for reading this and hopefully someday I’ll get this figured out.
 

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I know my 2006 GXP has a recall for the ignition switch, because if you hang too much from the key, it'll yank it down and possibly shut the car off. That probably also stresses the internals, which could affect passkey and such?

Mine's only had some minor turning issues, so I've never rushed to the dealership in the past 5yrs to get the "fix" (basically they tinker with it and put a smaller keyring hole on your key, hoping you don't hang much on the ring). I just leave the fob on mine, sometimes a house key, and stay mindful until I get around to a dealer.

Hope you get the E85 thing dialed. I'd suggest getting schooled up and equipped to do the tuning yourself, because that's going to require constant babysitting with the 30+% swing in E% at pumps. Keep 'er maintained and hopefully you see something in a scan that guides fixes.
 

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Discussion Starter · #3 ·
Hello, alround 3 years ago I bought a 2004 Pontiac Grand Prix gtp comp g, with 87000 miles on it. It had one problem and that’s why the guy got rid of it, it has always stored code p1626 theft deterrent fuel enable signal lost. It had always lost the signal after it was running so all it ever did was throw a code. Also having that code it would make my cars instrument gauges act crazy! I could be driving fine all of a sudden I lose my areoforce interceptor gauges they go out first, then two seconds later all my instrument cluster goes to 0 gas,tach,Speedo, and coolant all show nothing but the end he never misses a beat and I’ve found pulling over and shutting the car off and opening the drivers door momentarily will reset everything start it back up and it’s as if nothing was wrong. Now it could be 2 miles further and it could do it again or it could be hundreds of miles, it’s went months without doing it and it’s also did it 3 times in one day.
so ive been living with that I tried to look at the ignition harnesses a while back never found it out, now more recently a few weeks back I went to drive it and the fuel pump didn’t prime, I looked and all my instrument cluster was already faulted out before it cranked, well that make the car fire up and die a few seconds later. I took the other car and the next day it ran like nothing was wrong. Now two weeks later I just drive it yesterday and parked it in my drive and now the fuel pump won’t prime at all so it just cranks. Also have service stabilitrak, traction control is off abs light is on and for the last 5 weeks the brake Light was on. That had went off but I got a code u1040 lost comms with brake control module. Not sure if that has anything to do with it. I also yesterday night pulled the body control module and everything looks great from there. I swapped it out and now it states starting disabled due to theft. Codes changed from p1626 to p1631 start enable signal not correct. I’m not sure if I should try therelearn with the BCM or if I should put my old one back in. I pulled the plugs on the bcm checked for anything pushed out pins or broken wires as far as I can tell nothing is wrong. I wouldn’t think it came from the factory like this.
also have p0171 system to lean that I’ve been fighting with ever since I changed it over to e-85. I bought used 150 siemens injectors, a aem e85 fuel pump, and I sent my computer to get tuned to e85 from zzp. Ever since I gotthe computer back it has always ran lean, like 15.4-16 sometimes 17 when cruising on my wideband, when under pedal it’s correct at 10.4 but when cruising or idling it’s running lean. I bought a smoke tester thought I fixed it when I found a vacuum leak but it’s still there. Ive checked everything on that to. Not sure if it’s tuning. Or if when I swapped the fuel pump from the assembly the aem pump had no venture port for sucking extra fuel from bottom of tank. I’m just stumped as to why the car won’t fire up now. Maybe it is the body control module. Just want to seethe Grand Prix gurus opinions! Thanks! Let me know if you need any more information.
I know my 2006 GXP has a recall for the ignition switch, because if you hang too much from the key, it'll yank it down and possibly shut the car off. That probably also stresses the internals, which could affect passkey and such?

Mine's only had some minor turning issues, so I've never rushed to the dealership in the past 5yrs to get the "fix" (basically they tinker with it and put a smaller keyring hole on your key, hoping you don't hang much on the ring). I just leave the fob on mine, sometimes a house key, and stay mindful until I get around to a dealer.

Hope you get the E85 thing dialed. I'd suggest getting schooled up and equipped to do the tuning yourself, because that's going to require constant babysitting with the 30+% swing in E% at pumps. Keep 'er maintained and hopefully you see something in a scan that guides fixes.
I think that I might end up swapping the ignition myself one of these days. See what it takes to get that pass key sensor replaced or what not. I wouldn’t think it’s from excessive weight. Both my sets of keys have the key and the key fob and the zzp lanyard. And as for the e85 issue yeah I still have to check into that more to. My brother in law works for gm and has a really
Good scanner. He is just busy building his house at the moment. So hopefully soon. Thank you though for the insite!
 
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