When Started car will run as long as there is some accelerator pedal action, but as soon as the accelerator pedal is released the engine will run for about 15 seconds and die abruptly. It does not sputter or cough, it just quickly stops running. The trouble code p0641 (5V Reference 1 Circuit) is stored and comes back after clearing it every time. I am interested to know if anyone has any thoughts or experience with this sort of issue. I would appreciate any input or advice. Thanks.

 

Welcome to the Forum !!…What year is the car ??…always a good idea to fill out your profile with model year, mods, your location, tune etc…is this something you are going to try to diagnose yourself or do you want to know “what it may be” ??

 

Is this a new build or is this something that happened after it was running correctly?

Is it always about the same amount of time, or does it vary? And when you say action, do you mean that the pedal is simply off idle or do you mean that it is being moved consistently? The symptoms seem to be the same as would be experienced if you unplugged the pedal connector so it could be a loose connection...

Nick

 

Here are a couple of links that may be helpful; the first one actually has a fix, but the issue you are experiencing could easily be the wiring to the fast pedal and not the OPR as the discussion starter says fixed his problem in post number #5:

https://www.duramaxforum.com/threads...ce-shop.57172/

and from Google:
https://www.google.com/search?q=p064...client=gws-wiz

 

A 2006 Corvette with no modifications. It used to start and run perfectly, but just recently it’s been acting up. I want to get some input on the situation, that’s all. I work at a automotive shop and would feel comfortable performing any moderately simple repairs. I appreciate all the help y’all. Much Thanks.

 

And the engine always cuts off after the same duration of the accelerator pedal at idle. Any acceleration and the engine will run fine, but once it hits idle it’s always that same 15 seconds and then it’s done, it cuts right off.

 

Also I did begin a pinpoint test I found on AllData for the P0641. The 5 volt reference wire was shorted to ground on the MAP sensor and the A/C connector with the connectors connected and then disconnected. The 5 volt Reference circuit is shorted to ground.

 

The 5 volt Ref. is like the heartbeat of the car..the 5 volt ref. goes down and so will the other sensors...your scan tool should have a Data Pid for both 5 volt references...should either say Fault or OK I believe...yes, you just have to start disconnecting sensors until the 5 volt returns...do you know how to do a short to ground test ??

 

I tested the 5v reference wire to the MAP sensor for short to ground with the volt meter on the ohms setting, the battery disconnected, and my positive lead on the 5 volt reference wire and the negative lead on the ground terminal of the battery. I am thinking that since I already observed the voltages with the MAP sensor and A/C sensor out of the circuit and the 5 volt reference circuit still low, that maybe my next step is to unplug the accelerator pedal sensor and see if the voltage hits 5 volts then. I know a couple other sensors are included in the reference circuit besides the MAP, A/C & Accelerator sensors, like the gas tank pressure sensor and I think the camshaft position sensors too. I already bought a whole new PCM and had it programmed for the car but was not able to start the car once it was plugged in. So I now have the old one back in, have cleared all the fault codes and am starting from the beginning again. It has all the same exact symptoms as before and I forgot to mention that it does say “reduced engine power” lit up in the dash when the car is running.

 

Never heard of short to ground testing that way...you need to disconnect BOTH ends of that circuit....MAP and the particular connector for that wire at the ECM....ohm meter on HIGHEST resistance scale...one lead to the MAP 5 volt ref. and the other lead to a clean spot on the body....anything OTHER than "OL" is NO GOOD !!

 

any resolution with this issue? having similar problems LS2 C6 P0641, P0106, P0452 and sporadic oil pressure readings.

 

There are 6 sensors that can cause a P0641 so there will not be only one fix…you’ll have to do some troubleshooting !!…all your DTC’s are for 5 volt reference on circuit #1…it may be a short to ground pulling down the 5 volt ref…the MAP, EOP, Fuel Tank Pressure Sensor, APP, AC pressure sensor are involved..I’d do a good visual inspection first !!…you could disconnect both ECM connectors since all of these 5 volt refs go to the ECM and then do a “short to ground” check with your ohm meter…you will go from each sensor 5 volt ref wire at each sensor with one lead of the ohm meter and touch the other lead of your ohm meter to a clean ground…anything other than OL (open circuit) on your ohm meter is no good !!…video below which addresses a circuit 2 fault !!

 

The trouble code P0641 is logged whenever the PCM detects voltage that does not match manufacturer specifications on the 5-volt reference circuit1. A short on this rail will set code P06411. There could be multiple reasons for this issue. I suggest you take your car to a mechanic for a proper diagnosis.
https://dtcvehicles.com/