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Old 07-20-2022, 11:55 PM   #1
Bkob1471
 
Drives: 2010 Camaro 1SS M6
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Limp Mode…

I have been searching this forum for a couple weeks now and haven’t been able to find a hint at my issue so I am posting this to see if anyone can be of help. Thank you in advance for any advice.

A couple weeks ago I had an unusual thing happen where I made a bone headed mistake and tried to cross traffic on a busy street but instead of being in first gear I was in third… The car bucked hard and immediately went into limp mode and threw the code ECM P0641. I cleared the DTC with my flash tool and it drove fine afterwards. I took a log and sent it to my tuner to make sure nothing was wrong there and I got the all clear. Since then it seems like it will throw the code whenever I am making a left hand turn while on the throttle or whenever the car becomes even a little bit unsettled. Any help is greatly appreciated.
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Old 07-21-2022, 06:19 AM   #2
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Weird. I would disconnect the negative terminal on the battery and start looking for loose connections. Start at the ECM and don't forget to check the wires under the engine for damage. When you're done, reconnect the battery and clear the DTC's with your tool. You could have your tuner do a WRITE ENTIRE to your ECM and see if that helps.

Post your complaint on the HP Tuners forum and see what the pro tuners say.

Good Luck
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Old 07-21-2022, 07:07 AM   #3
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Quote:
Originally Posted by FasNuf View Post
Weird. I would disconnect the negative terminal on the battery and start looking for loose connections. Start at the ECM and don't forget to check the wires under the engine for damage. When you're done, reconnect the battery and clear the DTC's with your tool. You could have your tuner do a WRITE ENTIRE to your ECM and see if that helps.

Post your complaint on the HP Tuners forum and see what the pro tuners say.

Good Luck
I agree, sounds like a harness issue. A pinched or rubbed through wire pulling down the 5v reference bus.
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Old 07-21-2022, 04:21 PM   #4
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Thanks! I’ll get under the car this weekend and check the connections and grounds. Hopefully something will jump out at me.
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Old 07-21-2022, 04:28 PM   #5
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I would put your battery on a charger while it’s disconnected just to top it off.
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Old 07-30-2022, 08:41 PM   #6
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Well I checked what I could underneath the car and found nothing. Went and had the battery tested which checked out fine and cleaned up all the ground locations. The car is still throwing the ECM P0641 code but I can make it repeatable. So if I go over 50% throttle while in any gear and reach 3000 rpm’s it will immediately throw the reduced power mode and give the P0641 code. If I stay under 50% throttle I can go over 3000 rpm’s without throwing the code. Also I can free rev the motor above 3k rpm’s with the clutch in no problem. Am I looking toward the Throttle body or Accelerator position sensor possibly?
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Old 07-30-2022, 09:22 PM   #7
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No other codes are present?
I think you're onto something with the TB or Accelerator pedal by the sound of what that code means.

Last edited by FasNuf; 07-30-2022 at 09:38 PM.
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Old 07-31-2022, 07:01 AM   #8
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Electrical Issues are maddening - sometimes very difficult to diagnose.
I agree with FasNuf - I would start by checking connections - unplug, clean, and reassemble.
I know the GD Throttle Body ( and maybe Accel Pedal) Sensor is very sensitive and quick to throw codes. But Po641 can be related to other systems - ref this thread:
https://www.camaro5.com/forums/showt...ssure%20sensor


https://repairpal.com/obd-ii-code-p0...20is%205-Volts.
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Old 07-31-2022, 09:23 AM   #9
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So from what I've read, the code is saying there is an interuption in the 5 volt reference. The TB and Accelerator both use potentiometers. I had a car years ago give my fits because the throttle position sensor was so worn out in the cruise area that it no longer made contact there. I think that might be what's going on here.
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Old 08-04-2022, 01:28 PM   #10
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Quote:
Originally Posted by FasNuf View Post
So from what I've read, the code is saying there is an interuption in the 5 volt reference. The TB and Accelerator both use potentiometers. I had a car years ago give my fits because the throttle position sensor was so worn out in the cruise area that it no longer made contact there. I think that might be what's going on here.
So, unless one of the following sensors are shorted to ground, it's a harness or ecm issue! Shorted to ground is the only thing that will pull that 5v to zero. An open will not set this code.
Manifold absolute pressure (MAP) sensor... doubtful
Fuel tank pressure sensor.....doubtful
Accelerator pedal position (APP) sensor 2...possible
Engine oil pressure sensor...doubtful
Air conditioning (A/C) refrigerant pressure sensor...doubtful
Camshaft position sensor.....doubtful

The throttle position sensor is on a different 5v reference circuit. APP sensor 1 is on a different circuit as well, that's why your still able to drive the car. A bad APP is possible, I've never replaced one for this condition though....but they do fail frequently. My gut is telling me its a wiring issue. My suggestion is to disconnect the map sensor and put a voltmeter on the 5v terminal. then start moving and tugging the harness on the engine and under the dash near the pedal.

Last edited by NOT A 45; 08-04-2022 at 01:40 PM.
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Old 08-14-2022, 06:21 PM   #11
Bkob1471
 
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Thank you all for your responses…I still haven’t figured out the issue yet but I did plug in my EFILive Autocal device and went to show diagnostics where you can watch things in real time. I stopped on "TP" where it had a 28% value on the scanner and thought it was weird since I was idling in a parking lot. So I went home and turned off the engine but still had the key in the on position where I found the TP value was at 25% with no throttle input and only in the high 86-88% while pushing down full throttle. The picture attached is as the throttle sits with no input and the key in the on position. Is this normal?
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Old 08-15-2022, 09:24 AM   #12
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Originally Posted by Bkob1471 View Post
Thank you all for your responses…I still haven’t figured out the issue yet but I did plug in my EFILive Autocal device and went to show diagnostics where you can watch things in real time. I stopped on "TP" where it had a 28% value on the scanner and thought it was weird since I was idling in a parking lot. So I went home and turned off the engine but still had the key in the on position where I found the TP value was at 25% with no throttle input and only in the high 86-88% while pushing down full throttle. The picture attached is as the throttle sits with no input and the key in the on position. Is this normal?
Yes that is normal. What you want to do is slowly depress the pedal and observe the reading for anything erratic.
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Old 12-15-2022, 04:04 PM   #13
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Open up the harness at the front of passenger side head, it has a metal holder wrapped around the harness. Check for a short.
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