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SYS warning light on 1993

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SYS warning light on 1993

Sammy23 Sammy23
New User | Posts: 1 | Joined: 05/08
Posted: 05/08/08
03:24 PM

I drove my 1993 Vette to work today with no problem. Then I went out to eat and to my cousin's after work with no problem. Then, when I left my cousin's house the SYS light started flashing. I checked the manual and it just says it has something to do with the Central Control Module and I should get it serviced. Does anyone have any more information on it? My Vette has not acted up or anything, it is running fine and is getting very good mileage. Thanks a lot!  

Glenn413 Glenn413
New User | Posts: 4 | Joined: 03/08
Posted: 05/10/08
08:01 AM

I had the same thing happen on my '95.  I put a post here on the forum and another C4 driver told me to check my battery terminal to make sure there wasn't a loose connection and to make sure the alternator wasn't bad.  I did all that and I haven't seen the SYS light again.  Hope this helps.  

Viscount Viscount
User | Posts: 62 | Joined: 10/06
Posted: 05/10/08
11:41 AM

How old is your battery? It could be starting to fail.

I'd have it load checked in addition to what Glen 143 suggested.

If you don't drive your car frequently you may want to invest in a battery tender?  

SportsCarsUnlimited SportsCarsUnlimited
User | Posts: 74 | Joined: 03/08
Posted: 05/13/08
09:55 PM

There is a grounding point on the frame, Its down in front of the battery on the frame, Its one of the main chassis grounds for CCM and the ECM check it, It takes a 10mm or 13mm socket and a long extension, Just back it off a little then tighten it back. If your problem gos away clean the grounds and drive on.
David Steele  
Your One Stop Corvette Shop!

93WhiteTexas 93WhiteTexas
New User | Posts: 2 | Joined: 05/08
Posted: 07/18/08
09:51 PM

SYS indicator info

This document contains 2 references about the SYS indicator.

Corvette 1993 Owner's Manual page 120

The Central Control Module (CCM) controls several electronic systems on your Corvette. SYS will flash three times every 15 seconds on the display near the fuel gage if there is a problem with one of the CCM-controlled systems. Have your vehicle checked by a Chevrolet dealer if SYS keeps appearing.

If the SECURITY light flashes at the same time SYS flashes on the instrument panel, a problem has been detected in your theft deterrent system. If this occurs, have your vehicle serviced.


1993 Corvette Service Manual book 1 page 8D-4

NOTE: SYS isn't listed in the index of Service Manual books 1 and 2.

The Central Control Module (CCM) uses the speedometer, odometer, and the trip monitor located on the instrument cluster to display information while in the diagnostic mode.

The speedometer is used to display Diagnostic Trouble Codes (DTCs) (CCM, ABS/ARS and ECM), the odometer displays data, and the trip monitor indicates the system being tested and the test which is being performed. The buttons on the Driver Information Center (DIC) are used to send instructions to the CCM when in the diagnostic mode.

Unlike other vehicle electronic systems, such as ECM, SIR, etc., there is no specific "CCM" lamp to indicate a malfunction. A DTC-setting malfunction in any of the CCM-monitored systems is indicated by "SYS" (SYSTEM ERROR) flashing in the instrument cluster trip monitor. If a malfunction does not recur within 100 ignition cycles the CCM will automatically clear the DTC.

The "SYS" indicator will flash 3 times every 15 seconds while a current-DTC malfunction is present. An exception to the "SYS" malfunction indicator is that PASS-Key malfunctions (DTCs 51-53) will be indicated by the "SECURITY" lamp being illuminated without the "SYS" indicator flashing. If there is a Fuel Enable Data Stream (FEDs) malfunction (DTC 54), the "SECURITY" indicator and "SYS" indicator will flash together, to illustrate that the problem condition affects vehicle security.

To enter the diagnostic mode, ground (connect it to pin "A") pin "G" of the Data Link Connector (DLC) located under the right side of the dash, and turn the ignition switch to the "ON" position.

  A = Ground
  B = ECM Diagnostic
  C = Ride Control Diagnostic
  F = T.C.C (VIN P)
  G = CCM Diagnostic
  J = E&C Bus Data
  K = SIR Diagnostic
  L = SIR Serial Data
  M = Serial Data
DLC connector --> |F| | |C|B|A|
                 |G| |J|K|L|M|

- Important: If the A/C fuse is blown, the CCM will not receive IGN 3 power and will not enter diagnostic mode. This condition should also be indicated by a DCT 16 being set.

After turning the ignition "ON", the CCM will display any DTCs and the module for which they apply is an automatic DTC sequence. The CCM is module 1, the ECM is module 4, the ABS/ASR EBTCM is module 9. During the automatic display sequence, each DTC is displayed for three seconds, followed by a one second pause before the next DTC is displayed. There is a three second pause between the DTC display sequence for each module. The end of the DTC list for each module is indicated by "---" being displayed in the speedometer. If there is a communications problem between the ECM or EBTCM and the CCM, the speedometer will display "Err" when the CCM is trying to communicate with the ECM or EBTCM.

- Important: The CCM will display "Err" when attempting to display ECM DTCs for the LT5 engine. CCM display and cleaning of ECM DTCs is available only for the LT1. Use the Tech 1 for ECM DTCs on LT5.

The particular module being interrogated is indicated on the trip monitor, and the DTCs are displayed on the speedometer. The speedometer also indicates if the DCT is a current DTC (malfunction present now) or history DTC (malfunction has occurred, but is not present now) with a "C" or an "H", respectively. All ECM and EBTCM DTCs will be displayed by the CCM as history DTCs, weather they are current or history. ** reference

When all DTCs have been displayed for all modules, the trip monitor will display 1.0 and the speedometer will be blank; this indicates the CCM is in the manual mode, waiting for input from the technician. At any time during the automatic DTC display sequence, the manual mode may be entered by pressing any button on the DIC.

The manual mode can be entered as described previously, or will automatically be entered after the automatic DTC display sequence is complete.

When manual mode is entered, the speedometer will be blank, and the trip monitor will display "1.0", indicating that module "1" (the CCM) is ready for further instructions. The buttons on the DIC are used to control other systems and options as illustrated in Figure 4 (the Driver Information Center).

The indicator "--" will be displayed on the speedometer if the end or beginning of a list of malfunction DTC’s is reached (using the "Next Value" or "Previous Value" button). The "--" will also display if no DTC's are present for the module being checked.

If you get malfunction codes, post them and I'll post the meanings.  

mdv44 mdv44
New User | Posts: 1 | Joined: 12/08
Posted: 12/05/08
11:55 AM

i have a 96 with a ccm err message when trying to pull the fault codes. i do get two code of c81 and h81. i also show odo err in the mileage section. any help would be appreciated....  

Mike_Zarnock Mike_Zarnock
New User | Posts: 1 | Joined: 03/09
Posted: 03/22/09
07:12 AM

I have a "SYS" across the dash on my 91 also, but the engine will not idle and when I keep it running with keeping my foot on the throttle, it runs rich. I used my scan tool and the ECM checked out as fine. I get the "Service Engine Soon" light, but no codes! I even changed the ECM and nothing.... All connections are fine, battery is charging at 13 to 14 volts.... I am stumped. What are your thoughts. I called the Chevy Dealer and asked to order a CCM and they tell me they don't know what it is and can't order one. They don't even know where it's located in the car....  
Any help would be appreciated I know where it is and plan on pulling it out as soon as it gets warm enough here in NY....  

ajgonzalez ajgonzalez
New User | Posts: 1 | Joined: 04/09
Posted: 04/27/09
05:37 PM

I have an 84 and im having some what of the same problem. my security light is staying on and draining my battery. any suggestions?  

kcrick kcrick
New User | Posts: 3 | Joined: 07/08
Posted: 08/08/09
04:44 PM

Hey mdv...did you ever get your "odo err" fixed?  I found a CCM on ebay.  Everyone who sells them, used, calls them BCMs, but it's the same thing, behind the radio.  

markpartsplus markpartsplus
New User | Posts: 3 | Joined: 01/11
Posted: 01/22/11
09:35 AM

HELP...I have a 93 vette that will start and run for a second then shut down. I've rebuilt the computer 3 times, and replaced the ign. control module twice. It has new plug s and wires and new injectors. flash codes are h41, h64, h72, and h73. I've checked the signal from the distributor and its good. I do have spark but what evers happening is shutting the injectors off. The two white wires under the dash that come from the ignition cylinder read the same resistance as the key in all posisions. I still believe the problem is in the security sys. but I'm not 100% sure. Can anyone help me?  

waynep7122 waynep7122
Guru | Posts: 1114 | Joined: 08/09
Posted: 01/22/11
05:58 PM

do you have the trouble shooting diagrams and charts???

this should be the same as your car...

start with the code 41....

do you have access to a real scan tool????/   so you can see what the sensors are doing???/

i have seen craigs list OTC scan tools as cheep as 65 bucks that will work on your car..   you will have to have at least a 94 cartridge.. and the proper cable for it..  search for OTC     then look for monitor 2000, 4000, 4000E.. monitor extended.. or enhansed monitor.. or one of the genisys models...  a Snap on MT2500 will also do it...  the actron CP9110 will also work...

the only new scan tool that displays live data on these system is the OTC 3499N kit.. just over 500 bucks.. but the best of the bunch and will do all the new cars .... so its not an outdated piece of gear...

is the security light still flashing... when you try to start it...

start and die when the security light is on...   the VATS codes are in the ECM...  there are 15 different codes..

on the ECMs.. are you buying rebuilt ECMs/// or junk yard ecms that look the same???? as the code 74 is not used until 1994... according to what i have in print...

is there any chance of getting the model numbers off the COMPUTER and the broadcast numbers off the PROM inside...

you can start a new thread to stop from bouncing all over..   log in ... pull down the select forums bar  to one of the C4 forums and click GO to the right..  

vetteoz vetteoz
User | Posts: 58 | Joined: 07/08
Posted: 01/22/11
09:56 PM

Icon Quotemarkpartsplus:
flash codes are h41, h64, h72, and h73. I've checked the signal from the distributor and its good. I do have spark but what evers happening is shutting the injectors off.

DTC 41 is a loss or the serial data connection between the ECM and CCM
Very common on 90 - 93 cars
When this link is broken, the ECM does not get the fuel enable signal (part of VATS system ) from the CCM so it doesn't pulse the injectors
The fact the engine cranks shows the key reader and VATS component of the CCM are working correctly ; just that the ECM is not getting the right ( any ) fuel signal  

vetteoz vetteoz
User | Posts: 58 | Joined: 07/08
Posted: 01/22/11
10:01 PM

Icon Quotewaynep7122:
on the ECMs.. are you buying rebuilt ECMs/// or junk yard ecms that look the same???? as the code 74 is not used until 1994..
is there any chance of getting the model numbers off the COMPUTER and the broadcast numbers off the PROM inside...

The 1992-93 model years use ECM # 16159278.
It is visually similar to the 1990-91 Corvette weatherpak ECM. The connectors plug in the same way. It also has a removable prom chip. The later years ( PCM's ) do not.
This ECM has been long discontinued and many people have had problems with the rebuilt ones which is the only available option  

markpartsplus markpartsplus
New User | Posts: 3 | Joined: 01/11
Posted: 01/24/11
05:21 PM

yesterday while scanning corvette forum i found vette with same code 41 start then stall he replaced ecm and bcm fuel pump and finally replaced opti and it seem to take of his problem. this was only car that matched my smytoms i order a new dist. and waterpump today wish me luck  

vetteoz vetteoz
User | Posts: 58 | Joined: 07/08
Posted: 01/24/11
06:39 PM

Icon Quotemarkpartsplus:
i order a new dist.

Lot of $$$ before you have actually identified the problem
I would run through this  1st before outlaying money

In any case you have code 41 showing which will give crank / no start and has nothing to do with the Opti  

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