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SYS warning light on 1993

 
waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 01/24/11 08:54 PM

how about some more reading on the OPTISPARK...

optispark

1. LT-1 Ignition System - Getting to Know the Opti-Spark
Editor's Note: Way back in March of 1998, GMHTP ran "Opti-Spark" by Ray Bohacz, an engineering-level dissection of GM's Opti-Spark distributor. This evolutionary ignition ...

http://www.gmhightechperformance.com/tech/0310htp_lt1_ignition_system_understanding_modifying/index.html

2. Opti-Spark Options
The Opti-spark distributor is positioned on the front of the engine underneath the water pump, and works well in its designed environment--when it works. ...

http://www.corvettefever.com/howto/16758/index.html

3. Opti-Spark Ignition System Tune-Up
Don't be afraid that you can't even see your distributor. With new MSD goodies, you too can tackle the Opti-Spark tune-up.

http://www.carcraft.com/howto/ccrp_0603_opti_spark_tune_up/index.html

4. Corvette LT1 MSD Distributor - The OptiSpark Option
MSD comes to the LT1's rescue with its Pro-Billet distributor to replace the infamous OptiSpark ignition system

http://www.vetteweb.com/tech/vemp_0611_corvette_lt1_msd_distributor/index.html  

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roco
I love my Chevy Chevette!
Posts: 1
Joined: 04/11
Posted: 04/19/11 12:47 PM

Hey mike i have a 91 also and had the same problem exactly. i just got it back from repair shop, they replaced the fuel filter and injectors. so far it seems to run good,the sys light hasnt been on since its been fixed.hope this helps.  

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duggy94
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Posts: 1
Joined: 04/13
Posted: 04/01/13 04:42 PM

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.  

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janetlea
I love my Chevy Chevette!
Posts: 2
Joined: 04/13
Posted: 04/07/13 11:47 PM

I did the on board dignostic and security ligt and Sys flashed at the same time. Tested again and got codes 34, 36, 38. 41 and 54. Yesterday my 1993 corvette stalled at stop sign and then wouldnt start. Any suggetions?  

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waynep712222
My first time was in a Chevy
Posts: 129
Joined: 03/13
Posted: 04/08/13 06:09 AM

lets go over the codes first...
and i am taking that you have an LT1 version .. NOT the LT5 32 valve dual overhead cam motor..

i will explain these... so don't jump into changing parts yet..
Codes

34 MAP sensor circuit voltage low.

36 DI extra hi res pulse or extra low res pulse.

38.  i don't see a description for this.. i will dig deeper.

41. IC circuit open or shorted..

54. shows up on ZR1/LT5 models. for low fuel pump voltage..

lets go on to test... and please post which engine you have... the diagnostics are SLIGHTLY different on the ignition control section...  

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waynep712222
My first time was in a Chevy
Posts: 129
Joined: 03/13
Posted: 04/08/13 06:16 AM

if you car is in a quiet area...   and you have a friend... open the fuel door... take off the gas cap...  have the friend listen to the fuel tank when you turn the key ON.. there should be a slight whirring noise for the first 2 seconds...  this indicates the fuel pump relay is sending power to the fuel pumps and the fuel pumps are at least spinning..

if you cannot hear them.. you can use a length of something like  a yard stick between your ear and the filler neck..  have them cycle the key back on.


you can check the fuel pressure with a tester like this...

Image 13661  

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waynep712222
My first time was in a Chevy
Posts: 129
Joined: 03/13
Posted: 04/08/13 06:38 AM

on the ignition system... because of the HIGH voltages involved.. and you don't want to get shocked..

if you have a TIMING LIGHT...

Image 21062

clamp it around the thick coil wire from the coil on the left front of the cylinder head to the optispark down under the water pump.  rubber band the trigger in the ON position... then aim the timing light at the windshield... get in and crank the engine.. do you get a rapid flashing??? nice even pulses...???

if you do.. then move the timing light clamp to one of the spark plug wires....  there are 4 sticking out of either side of the cap..

hook it up and crank the engine again..  do you again get a flashing from the timing light... this time.  not as fast..

move it to another wire.. try again.. flashing is good...


can you test these ....

fuel pump spinning noise...  yes or no...

spark from the coil to the cap.. and from the cap to the spark plug wires..  yes or no....  

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janetlea
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Posted: 04/09/13 07:22 PM

I have the LT1. I cant do the test with the timing light as my car wont start  

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waynep712222
My first time was in a Chevy
Posts: 129
Joined: 03/13
Posted: 04/09/13 07:33 PM

go on with the tests above..

as for the timing light... you are using it to check for SPARK.. there is NO way to set the timing..

if you have a spare spark plug.. you can also. pull the coil wire off the cap.. and stick a spark  plug in the end and ground the shell.. see if you are getting spark from the coil... also spark from at least one spark plug wire..

copy and paste the instructions above into word..  follow them .,


spark or NO spark...

fuel pressure or NO fuel pressure...

this goes on from here...

see my other post about scan tools.. should be right at the top of the active posts..  i just bumped it..  

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offshore1
I love my Chevy Chevette!
Posts: 3
Joined: 08/13
Posted: 08/23/13 07:28 PM

I HAve a 1993 vette that wouldn't start,no fire,replaced the distributer,then still no fire Replaced the ignition control module, got it to start but dies out,i can keep it running if I keep fanning the accelerator, but when I stop or hold in one place it dies, driving me crazy...... please help...  

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offshore1
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Posts: 3
Joined: 08/13
Posted: 08/23/13 07:33 PM

can I do away with the security system on the 1993 vette.??  

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offshore1
I love my Chevy Chevette!
Posts: 3
Joined: 08/13
Posted: 08/23/13 07:34 PM

can I do away with the security system on the 1993 vette.??  

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waynep712222
My first time was in a Chevy
Posts: 129
Joined: 03/13
Posted: 08/23/13 08:13 PM

yes.... if you have a radio shack nearby...

a digital volt meter...


a section of european style terminal block.. also from radio shack...

i am talking about the VATS system... the one with the resistor in the key shank..

is your security light ON when it dies...

if so...

and you want to disable the VATS ignition key.

8Df9d8bb C8bb 4A00 9Ba0 552660B0d8e0 Zpsd39edae4

usually the Vats system will also disable the starter.. along with the fuel injector pulse width..

please check for codes as soon as you get a failed to start...

there are all kind of things on these that can cause a start and stall... or failure to run ...

and a hint.. if you wanted to reconnect the vats system.. you can just take the original vats key with you to the parts store.. pick up a new vats ignition lock cylinder with the orange harness.. it comes with 1 plain key... take the new plain key and your vats key with the resistor to the key cutter or locksmith shop.. have them measure the resistance of the key pellet.. select a new blank. 1 of 15 different resistance values..  have them use that blank and the NEW key to make a vats key to  the new lock..

be sure to make a second or ask which one of the 15 is it... mark that on the plain key.. and store the plain key at home..

you can now.. or later ..tear down the column and replace the entire cylinder.. or .. tie wrap the new resistor key into the new lock cylinder..  unwrap the harness and plug it into the proper cavities under the dash.. tie wrap the new lock up under the dash.. you have bypassed the vats system this way also...

but please check the codes.. before you go anywhere..

the vats security code will only last 4 minutes after a vats system activation that prevented a start...  

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waynep712222
My first time was in a Chevy
Posts: 129
Joined: 03/13
Posted: 08/23/13 08:35 PM

read the first page of this thread for info ..

or jump the A and B terminals of this..

Aldl




this is for the slightly earlier cars... the lt1 versions added a few more codes than whats here..

85 91Corvettecodes


you will want to print this chart also...
Scandatagm

starts and dies. is also the sign of a bad engine coolant temp sensor thats screwed into the front of the intake.. not the heads.. this tells the computer what the coolant temp is.. both sensor and pigtail have gone bad before.. this SU102 kit from autozone is under 20 bucks..

Su102

some LT1 owners have spend weeks swapping stuff only to find.. start and die because of this..
its about 2 minutes to examine it with a scan tool and the data chart above...  

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Benjamin Benmarcellus
I love my Chevy Chevette!
Posts: 5
Joined: 02/14
Posted: 05/18/14 09:27 AM

I am getting a code 41 on my 1991.How do you get the ECM to get the fuel signal? Will replacing the PROM fix this issue?  

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