Brainstorm idea need help (2MPH cutoff)
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Joined: Jul 2007
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From: west phoenix arizona
Brainstorm idea need help (2MPH cutoff)
Had a brainstorm today (normally scary)
I was thinking about the 2MPH fuel cutoff issue that a friend of mine is battling. I know that numerous people have had it turned off with a tuner, however I may have figured something out but need a schematic of the relay wiring that the PCM shuts off
Does anyone have a schematic of that relay wiring they could post?
I was thinking about the 2MPH fuel cutoff issue that a friend of mine is battling. I know that numerous people have had it turned off with a tuner, however I may have figured something out but need a schematic of the relay wiring that the PCM shuts off
Does anyone have a schematic of that relay wiring they could post?
Tech Contributor
Joined: Jan 2007
Posts: 19,482
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From: Dyer, IN
Had a brainstorm today (normally scary)
I was thinking about the 2MPH fuel cutoff issue that a friend of mine is battling. I know that numerous people have had it turned off with a tuner, however I may have figured something out but need a schematic of the relay wiring that the PCM shuts off
Does anyone have a schematic of that relay wiring they could post?
I was thinking about the 2MPH fuel cutoff issue that a friend of mine is battling. I know that numerous people have had it turned off with a tuner, however I may have figured something out but need a schematic of the relay wiring that the PCM shuts off
Does anyone have a schematic of that relay wiring they could post?
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Joined: Jul 2007
Posts: 62
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From: west phoenix arizona
I believe the issue is column lock related.
Pretty sure it's not security related because the security system kills fuel entirely.
The 2MPH is part of the column lock recall flash GM did.
What Im looking for is the schematic of the relay wiring that gets killed when the 2MPH parameter is set because of GM's wonderful reflash of the PCM
Any help with a schematic would be great.
Also what service manual is the one that I see people post these schematics out of so I can buy my own for future reference?
Pretty sure it's not security related because the security system kills fuel entirely.
The 2MPH is part of the column lock recall flash GM did.
What Im looking for is the schematic of the relay wiring that gets killed when the 2MPH parameter is set because of GM's wonderful reflash of the PCM
Any help with a schematic would be great.
Also what service manual is the one that I see people post these schematics out of so I can buy my own for future reference?
Last edited by AZ99; Nov 10, 2008 at 07:54 PM.
Tech Contributor
Joined: Jan 2007
Posts: 19,482
Likes: 1,173
From: Dyer, IN
I believe the issue is column lock related.
Pretty sure it's not security related because the security system kills fuel entirely.
The 2MPH is part of the column lock recall flash GM did.
What Im looking for is the schematic of the relay wiring that gets killed when the 2MPH parameter is set because of GM's wonderful reflash of the PCM
Any help with a schematic would be great.
Also what service manual is the one that I see people post these schematics out of so I can buy my own for future reference?
Pretty sure it's not security related because the security system kills fuel entirely.
The 2MPH is part of the column lock recall flash GM did.
What Im looking for is the schematic of the relay wiring that gets killed when the 2MPH parameter is set because of GM's wonderful reflash of the PCM
Any help with a schematic would be great.
Also what service manual is the one that I see people post these schematics out of so I can buy my own for future reference?
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From: Gone
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St. Jude Donor '03
I could be mistaken, but I highly doubt you'll find any external wiring or relays related to this. At least there should be no need for that.
The BCM and PCM communicate via the serial data bus, and anytime the PCM gets the nod from BCM to shut down, the PCM does so by not firing the injectors. What the GM recall did was tweak the BCM to introduce this particular shut-down command in column lock failure situations.
Tuning software can break/alter that BCM command, but I don't think you'll find a wire to snip or a fuse to pull that will stop it.
That's the simplified version as I understand it.
The BCM and PCM communicate via the serial data bus, and anytime the PCM gets the nod from BCM to shut down, the PCM does so by not firing the injectors. What the GM recall did was tweak the BCM to introduce this particular shut-down command in column lock failure situations.
Tuning software can break/alter that BCM command, but I don't think you'll find a wire to snip or a fuse to pull that will stop it.
That's the simplified version as I understand it.
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Joined: Jul 2007
Posts: 62
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From: west phoenix arizona
I could be mistaken, but I highly doubt you'll find any external wiring or relays related to this. At least there should be no need for that.
The BCM and PCM communicate via the serial data bus, and anytime the PCM gets the nod from BCM to shut down, the PCM does so by not firing the injectors. What the GM recall did was tweak the BCM to introduce this particular shut-down command in column lock failure situations.
Tuning software can break/alter that BCM command, but I don't think you'll find a wire to snip or a fuse to pull that will stop it.
That's the simplified version as I understand it.
The BCM and PCM communicate via the serial data bus, and anytime the PCM gets the nod from BCM to shut down, the PCM does so by not firing the injectors. What the GM recall did was tweak the BCM to introduce this particular shut-down command in column lock failure situations.
Tuning software can break/alter that BCM command, but I don't think you'll find a wire to snip or a fuse to pull that will stop it.
That's the simplified version as I understand it.
What GM did was introduce a software scenario to over ride the original factory operation. Numerous people including my friend have this issue after having the recall done and after installing a CLB. Prior to GM implementing the recall and the reflash I don't see a history of the 2MPH cutoff being a problem? I believe I have figured out a hardware solution to this problem, However I would like to verify my proposed solution against the wiring schematics prior to implementing them in my friends car.
I do know it can be "fixed by a tune" however I would like to find a solution that is not as cost prohibitive and also helps those that are not close to a tuner.
Le Mans Master
Joined: Sep 2007
Posts: 7,604
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From: Belleville Il
My car had 2 of the recalls done before I bought it. The 2nd one,, RC04006 included the words "Perform reprogram and functional test" theis was in case their crappy K harness F**ked up it would kill the fuel over 2mph. I can verify IT DOES!!! Ask me how I know
!!!
:cheers :
!!!:cheers :
Race Director
Joined: Oct 2002
Posts: 16,477
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From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Yes, but my point was...with software changes you are not dealing with wiring schematics...because there are none. No hard wiring changes took place.
If you think you can break the communication between the BCM and PCM completely, your car will not start or run, period. (without software changes - PCM tuning).
If you think you can break the communication between the BCM and PCM completely, your car will not start or run, period. (without software changes - PCM tuning).
Drifting
Joined: Jan 2005
Posts: 1,517
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OP:
I think you're looking at this wrong.. it's not that a wire suddenly gets voltage when the 2mph cutoff is in place.. the PCM knows that it's limited to 2mph and then kills the fuel when it detects it at 2mph. You CAN NOT cut a wire and have the car continue to run and avoid the 2mph cutoff. It's dead simple to get rid of in HPtuners, your buddy needs to find someone with a copy and get it taken care of...
I think you're looking at this wrong.. it's not that a wire suddenly gets voltage when the 2mph cutoff is in place.. the PCM knows that it's limited to 2mph and then kills the fuel when it detects it at 2mph. You CAN NOT cut a wire and have the car continue to run and avoid the 2mph cutoff. It's dead simple to get rid of in HPtuners, your buddy needs to find someone with a copy and get it taken care of...
Melting Slicks
Joined: Feb 2006
Posts: 3,191
Likes: 43
From: Scottsdale Az
P.S. Should have stayed the hell away from the dealer.
Well stated !
