PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

Hard Hit - No Start Until PCM Reset...why?

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Old Oct 21, 2014 | 11:01 AM
  #1  
jrtoffroad's Avatar
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Default Hard Hit - No Start Until PCM Reset...why?

Hey guys I have an LS1 in my Ultra4 off-road race car. I was at a race this weekend and took a hard hit on the driverside rocker. When I took the hit the engine immediately died (as if the key was turned off) and would not re-start. Fuel pump relay was not getting a signal from the PCM. After the race I pulled the PCM to check the wiring. Everything was fine so I put the PCM back in (after about 15min) and the engine fires right back up. I was able to run the next heat race without issue.

Is there any kind of accident sensor in the PCM? Should this happen or is my PCM going bad? The wiring on this jeep is custom, with no emissions, no airbags, etc.

Thanks for your help! Whether I need a new PCM or not, I'm going to redo my mount with some rubber isolators.

-Jordan
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Old Oct 21, 2014 | 12:32 PM
  #2  
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I'm not sure whether it's PCM, BCM or a tag team thing
but this action replaces the old rollover switch function.
Not sure how you'd inhibit it (other than eliminating PCM
control of the fuel pump relay altogether and making it
simply key-controlled) but seems like if you're in a
"rubbin' is racin" type event, you would want it gone.
Or replaced by some more robust yet acceptably
effective safety scheme.
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Old Oct 21, 2014 | 05:03 PM
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Okay, so it is a real thing and it only inhibits the fuel pump? That's easy enough to fix! I've been thinking about running the fuel pumps on a dedicated switch anyways.

Thanks for your input!
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Old Oct 25, 2014 | 07:48 AM
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Is the pcm soft mounted??
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