C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

SYS message after a Stereo Upgrade (Details)

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Old Feb 10, 2012 | 07:27 AM
  #1  
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Default SYS message after a Stereo Upgrade (Details)

Hi All,

Have a query to this "sys" message that comes up when an after market stereo is installed. I am aware of the error code is C72/H72.

I am wanting to know does the sys message flash constantly or only on certain light conditions detected by the light dependent resister on the button panel.

The reason I ask this question, now that my ECM/CCM is working as it should, I am only getting a momentary (3-5 minutes) sys message comes up only on very bright sunny days. At the same time my backlite display on the speedo goes dark. But after that it goes back to normal and the sys message goes away. No other error comes up and all is well.

Can go for a trip for hours and I will never see a sys or speedo going dim. At night I have never seen it happen, everything works perfectly.

Is this the symptom of an aftermarket stereo installed with no resistors fitted. I've pulled apart my stereo (to fix up due to some bubba wiring and fitting) and did not see any resistors added.

Cheers,
Gary.
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Old Feb 10, 2012 | 07:56 AM
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I dont think the missing bulbs is causing anything more than the sys flashing. if you took it apart to check it why not just slide 5 cent resistors into the appropriate connection points and at least take care of the sys?
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Old Feb 10, 2012 | 09:38 AM
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disconnect your battery for ten minutes, see if it goes away for good, if it comes back you have an issue
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Old Feb 11, 2012 | 09:05 AM
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Originally Posted by oldalaskaman
disconnect your battery for ten minutes, see if it goes away for good, if it comes back you have an issue
My C4 is not a daily driver so I have an isolator switch. When re-connect the battery and I start it I do not get the sys message.

Hence my question, is the sys C72 fault related to the aftermarket stereo a constant error or does it only come up on occasions?
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Old Feb 11, 2012 | 10:29 AM
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the answer to that should be neither, pull your codes
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Old Feb 11, 2012 | 11:47 AM
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My 90 needed the resistors.

Knew about the fix, had the new system on the shelf for 6 months before I had time to install it & forgot about the resistors. Pulled the head & installed the resistors to make things right.
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Old Feb 12, 2012 | 10:16 AM
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you need the .5 ohm resisters, 2 of them.
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