dash flashing "SYS"
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 1,123
Likes: 1
From: Rockland County NY
dash flashing "SYS"
any thoughts on this? Car is a 91 L98 6spd. The spot on the upper left corner of the speedometer, where the average mpg usually displays, now flashes SYS every minute or so. Wtf???
Le Mans Master
Joined: Oct 2004
Posts: 6,314
Likes: 508
From: South-central Missouri
Interesting! Learn something every day. What did you (assuming it was you) do to clear the SYS light after installing the new stereo??
To the OP:
The flashing SYS is indicative of low voltage, for one of many reasons. But, the first place to start is with the alternator. If the engine is running, there should be 13.5+ volts across the battery terminals. If it gets down to below 12, at some point the SYS flashes, indicating a low voltage problem. (A place to start!)
P.
Race Director
Joined: Oct 2005
Posts: 11,768
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From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
http://forums.corvetteforum.com/audi...audio-faq.html
TSB regarding the flashing SYS after an aftermarket stereo install.
Seems to only affect the '90-'93
http://www.corvetteforum.net/c4/dave8476/index4.shtml
As mentioned in the first reply, a low battery is usually the number 1 cause of the flashing SYS.
But if the OP has just installed an aftermarket stereo, that would probably be a good place to start looking too.
Intermediate
Joined: Jul 2011
Posts: 43
Likes: 0
From: Rohnert Park, CA
Thanks for backing me on that one RollaMo. I totally agree that it seems strange that removing or replacing the factory installed stereo causes "SYS" to flash. But I have a 96 LT1 & put a Pioneer In-Dash DVD Stereo Receiver in and happened to me. But thanks to this forum I was able to correct the problem with the information I received. 
Race Director
Joined: Oct 2005
Posts: 11,768
Likes: 175
From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
Thanks for backing me on that one RollaMo. I totally agree that it seems strange that removing or replacing the factory installed stereo causes "SYS" to flash. But I have a 96 LT1 & put a Pioneer In-Dash DVD Stereo Receiver in and happened to me. But thanks to this forum I was able to correct the problem with the information I received.
I did not get the flashing SYS though.
Not sure why it affects some and not others.
The TSB I linked too about only mentions '90-'93
Intermediate
Joined: Jul 2011
Posts: 43
Likes: 0
From: Rohnert Park, CA
I know. It's total craziness. Just goes to show us although they may look alike they all have their own moodiness which is why I think forums were created.
You just gotta love the sense of humor the guys in Bowling Green seem to have sometimes.
You just gotta love the sense of humor the guys in Bowling Green seem to have sometimes.
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Burning Brakes
Joined: Nov 2010
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From: Crystal Springs MS
Intermediate
Joined: Jul 2011
Posts: 43
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From: Rohnert Park, CA
Well all I know is it wasn't flashing when I drove my car down to get the stereo installed. But it definitely was when I drove it home. When I got home I jumped on the computer and found this issue and what to do to fix it. So...
Race Director
Joined: Oct 2005
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From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
If you have the C68 HVAC option, the control head puts enough lamp resistance on the line to prevent the SYS light. I've only heard of 1 or 2 people with the stock AC not have the SYS flashing after installing aftermarket stereos. My stock '94 needed the resistors, my '96 with C68 did not.
Le Mans Master
Joined: Aug 2011
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St. Jude Donor '16
Le Mans Master
Joined: Dec 2006
Posts: 5,139
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From: H-Town Texas
I have seen this on occaision. I do still have the stock audio. I also have the automatic climate control.
The first time I saw it was shortly after I got the car. Not knowng much at the time, I spent about two hours on day on my first detailing. Of course the PKE kept locking and unlocking. Went to go for a drive, and the battery was dead. Got a jump from a neighborly gentleman with a battery jumper. The "sys" flashed for a bit then stopped. I did replace that battery in short order and learned from my mistake.
Some time later it happened to me again. What I learned was that the negative battery terminal was stripped. This would cause intermittant blackout when starting the car, and the sys would flash on occaision. Replaced the terminal and I don't recall seeing it since.
The first time I saw it was shortly after I got the car. Not knowng much at the time, I spent about two hours on day on my first detailing. Of course the PKE kept locking and unlocking. Went to go for a drive, and the battery was dead. Got a jump from a neighborly gentleman with a battery jumper. The "sys" flashed for a bit then stopped. I did replace that battery in short order and learned from my mistake.
Some time later it happened to me again. What I learned was that the negative battery terminal was stripped. This would cause intermittant blackout when starting the car, and the sys would flash on occaision. Replaced the terminal and I don't recall seeing it since.
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 1,123
Likes: 1
From: Rockland County NY
Sorry guys, been away from the computer for a while...
Well, I hate to put the brakes on this informative discussion about aftermarket stereos, but Ive had the same stereo in it for 7 or 8 years now!!! The battery is getting old though, I'll have to test that and the output of the alternator. Thanks for your input...
Well, I hate to put the brakes on this informative discussion about aftermarket stereos, but Ive had the same stereo in it for 7 or 8 years now!!! The battery is getting old though, I'll have to test that and the output of the alternator. Thanks for your input...
Racer
Joined: Mar 2011
Posts: 304
Likes: 0
From: Victoria Australia
My 1990 did have this sys flash for over a year until the ECM decided to completely quite on me. 1990's and 1991 are very similar and the first model to have the CCM->ECM combination and can be a nightmare even amongst the C4 elitest to fix.
First tip, the "sys" flashing every 15 seconds on your dash board indicates a code has been triggered in your CCM. One cannot assume its the battery or anything else unless you ground the ALDL connector and check the codes stored. A current code will be displayed as a C with a number and a code that is intermittent will have a H with a number for History.
I would advise to get a a workshop manual and using a paper clip ground the ALDL connector and get familiar with the diagnostics. This is the only way to avoid speculation. Once you pull the trouble codes we can help with what to do next.
Phat98,
Thanks for the tip on the C68 option having enough resistance without the need of the aftermarket resistor fix to avoid the "sys" flashing issue. No wonder mine works fine despite having an Alpine stereo.
First tip, the "sys" flashing every 15 seconds on your dash board indicates a code has been triggered in your CCM. One cannot assume its the battery or anything else unless you ground the ALDL connector and check the codes stored. A current code will be displayed as a C with a number and a code that is intermittent will have a H with a number for History.
I would advise to get a a workshop manual and using a paper clip ground the ALDL connector and get familiar with the diagnostics. This is the only way to avoid speculation. Once you pull the trouble codes we can help with what to do next.
Phat98,
Thanks for the tip on the C68 option having enough resistance without the need of the aftermarket resistor fix to avoid the "sys" flashing issue. No wonder mine works fine despite having an Alpine stereo.
Last edited by XR_Strider_GuY; Oct 7, 2012 at 09:19 PM.
Burning Brakes
Joined: Nov 2010
Posts: 855
Likes: 36
From: Crystal Springs MS
Racer
Joined: Oct 2012
Posts: 348
Likes: 28
From: Houston TX
I had the same problem after I took the door panel off and put it back on. Apparently I short circuited the courtesy light fuse (I forgot to disconnect the negative terminal) Anyways if one of your courtesy light fuses is blown it will throw the same SYS light.
Advanced
Joined: Sep 2011
Posts: 57
Likes: 0
From: Pierre SD
[QUOTE=RollaMo-LT4;1582006668]Possible
This has been noted several times in the past, and is listed in the Audio FAQ's.
http://forums.corvetteforum.com/audi...audio-faq.html
TSB regarding the flashing SYS after an aftermarket stereo install.
Seems to only affect the '90-'93
http://www.corvetteforum.net/c4/dave8476/index4.shtml
======================================== =========
It did affect my 1994. I had to put the resistors in line to get the sys flashing to go away. I'll post my pictures of the process this weekend. You will need to be able to do some sodering or crimping of wires. Not a bad processes but challenging due to tight space.
Dave in Pierre, SD
This has been noted several times in the past, and is listed in the Audio FAQ's.
http://forums.corvetteforum.com/audi...audio-faq.html
TSB regarding the flashing SYS after an aftermarket stereo install.
Seems to only affect the '90-'93
http://www.corvetteforum.net/c4/dave8476/index4.shtml
======================================== =========
It did affect my 1994. I had to put the resistors in line to get the sys flashing to go away. I'll post my pictures of the process this weekend. You will need to be able to do some sodering or crimping of wires. Not a bad processes but challenging due to tight space.
Dave in Pierre, SD
Le Mans Master
Joined: Aug 2011
Posts: 5,599
Likes: 10
St. Jude Donor '16
[QUOTE=dvoeltz;1582047668]
Thank you. 
any help would be appreciated.
Possible
This has been noted several times in the past, and is listed in the Audio FAQ's.
http://forums.corvetteforum.com/audi...audio-faq.html
TSB regarding the flashing SYS after an aftermarket stereo install.
Seems to only affect the '90-'93
http://www.corvetteforum.net/c4/dave8476/index4.shtml
======================================== =========
It did affect my 1994. I had to put the resistors in line to get the sys flashing to go away. I'll post my pictures of the process this weekend. You will need to be able to do some sodering or crimping of wires. Not a bad processes but challenging due to tight space.
Dave in Pierre, SD
This has been noted several times in the past, and is listed in the Audio FAQ's.
http://forums.corvetteforum.com/audi...audio-faq.html
TSB regarding the flashing SYS after an aftermarket stereo install.
Seems to only affect the '90-'93
http://www.corvetteforum.net/c4/dave8476/index4.shtml
======================================== =========
It did affect my 1994. I had to put the resistors in line to get the sys flashing to go away. I'll post my pictures of the process this weekend. You will need to be able to do some sodering or crimping of wires. Not a bad processes but challenging due to tight space.
Dave in Pierre, SD
any help would be appreciated.
2nd Gear
Joined: Apr 2013
Posts: 2
Likes: 0
sys
Looks like that sys error can come on for just about anything. My 94 had that light on since I bought it a year ago. Last week the trip monitor to right side of dash for all fuel switches, ilumination light would go on and off intermitenly. Friday I found the problem. a four prong plug was loose behind it.
Fix- remove 4 screws around speedomiter bezel and loosen.Reach up behind trip monitor and push plug back in. Next day I see sys error no longer there.
Fix- remove 4 screws around speedomiter bezel and loosen.Reach up behind trip monitor and push plug back in. Next day I see sys error no longer there.