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SES issue

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Old 03-23-2019, 11:22 PM
  #1  
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Car: 91 Camaro RS
Engine: 305 TPI conversion.
Transmission: T56
Axle/Gears: 3.73 posi 4th gen rear
SES issue

1991 tpi 6 spd.
car was running well. i switched out the plenum and runners for slp runners. I dropped in a used msd distributor, but went bqack to the original due to a possible bad pick up coil. I reset timing as your supposed to and idle is at 1k rpm. i noticed the fan slowly turning which they didnt before. engine has a slight vibration. i dont hear or feel any vacumm leaks. i went to check for codes and the SES is not coming on at ignition or when A and B are connected.
I didnt run the engine loger than about ten minutes at a time. wondering if i need it to run longer for the computer to reset. or is it something else
thanks

Last edited by tonys91rs; 03-23-2019 at 11:54 PM.
Old 03-24-2019, 12:42 AM
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Car: 86 Imponte Ruiner 450GT, 91 Formula
Engine: 350 Vortec, FIRST TPI, 325 RWHP
Transmission: 700R4 3000 stall.
Axle/Gears: 9 Bolt Torsen 3.70
Re: SES issue

SES should work at key-on. That is the bulb check. If that doesn't work and the bulb/circuit is good then the ECM is bad.

GD
Old 03-24-2019, 12:59 AM
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Join Date: Mar 2002
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Received 8 Likes on 6 Posts
Car: 91 Camaro RS
Engine: 305 TPI conversion.
Transmission: T56
Axle/Gears: 3.73 posi 4th gen rear
Re: SES issue

i doubt the bulb just went out but possible. it was working the day before. but i will check it. with a bad ecm the car will start and run?
Old 03-24-2019, 02:15 AM
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Car: 86 Imponte Ruiner 450GT, 91 Formula
Engine: 350 Vortec, FIRST TPI, 325 RWHP
Transmission: 700R4 3000 stall.
Axle/Gears: 9 Bolt Torsen 3.70
Re: SES issue

Yes it could. There is a resistor network built into the memcal that can run the engine in limp mode even if the ROM is corrupt, etc.

Lack of SES light and inability to pull codes is very similar to my original 7165 ECM that had a cracked circuit board. Sometimes it would run - sometimes it wouldn't. And it's behavior would change if you tapped on it with a screwdriver handle.

But it's probably related to the recent work and the bulb or the circuit may to be blame. Check those first. If you ground the pin on the ECM the bulb should lite. Also check all the grounds for the ECM. It can't ground the bulb if it doesn't have a ground reference.

1k is wrong for idle speed. At least with a stock ROM anyway. 650 is about where the stock ROM will idle.

GD

Last edited by GeneralDisorder; 03-24-2019 at 02:19 AM.
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