sys on dash
Team Owner
Joined: Aug 2004
Posts: 21,543
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From: Park City Utah
Here is a basic schematic of the serial data wiring...
If you test that assembly for continuity, shorts to ground, and shorts to power, that is about all the testing you can do. The pic above gives your connector and terminal numbers to orient yourself.
If you test that assembly for continuity, shorts to ground, and shorts to power, that is about all the testing you can do. The pic above gives your connector and terminal numbers to orient yourself.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
O.K. In addition to checking the tan wires in the above schematic, you can also check continuity in the Dark Green/White wire from the ECM (Pin #B8) to the CCM (Pin #E2). Also check for shorts to ground, power.
Thread Starter
Burning Brakes
Joined: Jul 2000
Posts: 1,045
Likes: 3
Okay heres what i didcovered this morning. Someone suggested i go back to square one and check things that have been altered . Over the winter I had the whole stereo repaired. So I removed the radio head unit in the dash and the sys is no long on. I have another head unit I am going to borrow and see if the problem is solved. The fuse that operates the head unit was also one the was giving me a draw with key off when I was having the battery drain problem. Might be onto something. After I check the radio ill get back to you.
Also have a replacement ECM to see if that helps the SES light problem.
Also have a replacement ECM to see if that helps the SES light problem.
Burning Brakes
Joined: Jan 2002
Posts: 1,228
Likes: 1
From: Dallas Texas
There is a modification that involves adding two 1K resistors to the GM stereo harness for aftermarket stereos. Whoever redid the stereo might not have known what they were for and removed them?
Thread Starter
Burning Brakes
Joined: Jul 2000
Posts: 1,045
Likes: 3
ccm unplugged and with multi meter conected to the neg. I have a a ground at d20 and nothing at d15. Meter to pos and I get 12v at d20 and nothing at d15. So d15 is always dead and d20 is a ground.............
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Team Owner
Joined: Aug 2004
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From: Park City Utah
Let me look at the ZR-1 info....
Last edited by Tom400CFI; Apr 18, 2010 at 09:26 PM.
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
Never heard of such a thing. I believe that it's possible to over work a weak alternator, doing such a task.
But the statement The alternator doesn't put enough juice out to charge it.....that isn't correct. The Alternator does. Maybe to it's detriment, (though I've never seen that happen), but it puts out the volts and amps to charge a battery, given time.
Either way, The OP doesn't have a stone dead battery. Or a dead battery at all. The alternator, if working will certainly keep a decent or even marginal battery, UP. Agreed?
But the statement The alternator doesn't put enough juice out to charge it.....that isn't correct. The Alternator does. Maybe to it's detriment, (though I've never seen that happen), but it puts out the volts and amps to charge a battery, given time.
Either way, The OP doesn't have a stone dead battery. Or a dead battery at all. The alternator, if working will certainly keep a decent or even marginal battery, UP. Agreed?
RACE ON!!!
Thread Starter
Burning Brakes
Joined: Jul 2000
Posts: 1,045
Likes: 3
The ecm is where d15 and 20 are at wc13 is the wire on the ccm. Talked to K&B this am. I might have fried the ccm jump starting the car this spring. The ccm and ecm will be shipped in the morning to them. It will take about a week to get them back.
SES light might be a different issue. We'll see if that helps...
SES light might be a different issue. We'll see if that helps...
Thread Starter
Burning Brakes
Joined: Jul 2000
Posts: 1,045
Likes: 3
If you read above I noted the ecm D15 data wire is dead and D20 has a 12v . I have about a dozen gremlins since the stereo replacement. Like when the interior lights come on the abs relays scatter. Air bag system is energised with key off, schock servos motors operating while key off. Something is powerering the car. None of this before the stereo, everything I have issues with all tie into the ccm. I talk to Ken at K&B and was told jumping a dead battery is a killer on ccms. Guess what i did! So I need to narrow it down before i keep chasing my tail. I find it hard to believe the wiring harness just took a fall at this time. But stranger things happen.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
If you read above I noted the ecm D15 data wire is dead and D20 has a 12v . I have about a dozen gremlins since the stereo replacement. Like when the interior lights come on the abs relays scatter. Air bag system is energised with key off, schock servos motors operating while key off. Something is powerering the car. None of this before the stereo, everything I have issues with all tie into the ccm. I talk to Ken at K&B and was told jumping a dead battery is a killer on ccms. Guess what i did! So I need to narrow it down before i keep chasing my tail. I find it hard to believe the wiring harness just took a fall at this time. But stranger things happen.
FYI, I don't believe that you SHOULD see any voltage at pin D15 (at the ECM) Using a DVOM, it should appear "dead" on the DC voltage scale. Terminal D20 should show 5v according to my chart, so something might be amiss there (short to power?).
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
[QUOTE=ninetyfivevette;1573792338]There is a modification that involves adding two 1K resistors to the GM stereo harness for aftermarket stereos. Whoever redid the stereo might not have known what they were for and removed them?[/QUOTE
My son's 96 LT1 is experiencing the same flashing 'SYS' light . He just never got around to installing the resistors.
What wires should they be spliced in to?
Thanks,
Jake
My son's 96 LT1 is experiencing the same flashing 'SYS' light . He just never got around to installing the resistors.
What wires should they be spliced in to?
Thanks,
Jake
Le Mans Master
Joined: Jan 2010
Posts: 8,553
Likes: 3
[QUOTE=JAKE;1573831347]
Look here
http://forums.corvetteforum.com/audi...t-fix-diy.html
There is a modification that involves adding two 1K resistors to the GM stereo harness for aftermarket stereos. Whoever redid the stereo might not have known what they were for and removed them?[/QUOTE
My son's 96 LT1 is experiencing the same flashing 'SYS' light . He just never got around to installing the resistors.
What wires should they be spliced in to?
Thanks,
Jake
My son's 96 LT1 is experiencing the same flashing 'SYS' light . He just never got around to installing the resistors.
What wires should they be spliced in to?
Thanks,
Jake
http://forums.corvetteforum.com/audi...t-fix-diy.html