sremenap

Went out to my car this morning, and the digital display is flashing SYS, and it wont start.

It did this to me once before, and miraculously fixed itself. It has a new fuel pump, injectors, battery, and will crank for days.

Searching here, googling it, and of course looking through the manuals dont help me. What does the flashing SYS mean? - this is my daily driver.

brookman

I have about the same problem - I am getting ready to switch out the computer.

take a look at my symptoms.

http://forums.corvetteforum.com/show...49&forum_id=48

Jet-Jock

Check the condition of your battery connections.

Verify you have a good battery.

Also, pull your CCM codes. You probably have a DTC set.

Jet-Jock

I read your other post. The reason you probably had a fuel system fault is probably because the ECM enabled the FEDS mode which prevents the fuel system from being enabled.

Changing out the ECM is a fairly easy job. The most difficult part is getting access to the one little nut the bury inside the bracket. I commented on the other post about changing the PROM.

Have you contacted Chris at Superior for price on an exchange ECM? I just had to change mine, it was very reasonable.

Brian9

I agree with 93 Jet Jockey... In your manual it should say (at least it says it in my 95 owners manual) that there is something wrong with your electrical system when the SYS flashes. Hopefully its just the battery like it was on mine when i bought it. My freinds dad hadnt driven it in a couple of months and the battery was almost dead and the sys light was flashing....But after it was driven 450 miles from atlanta to tampa it works fine now no more sys flashing So take Jet Jockeys advice and check your battery and connections first...

sremenap

appreciate the responses guys.

Yeah i checked the battery first, thats why i mentioned it would crank for days. Connections are tip top as well.

Jet-Jock

Next step is you need to pull codes. When you said 'looking through the manuals' are you referring to the owners manual or service manuals?

Sorry the obvious wasn't the issue, normally when the conditions you describe its the battery.

SYS flashes three times every fifteen seconds when there is a problem with one of the CCM controlled components. If your getting a SYS and SECURITY flashing at the same time then you'll need to look at the theft deterrent system.

sremenap

Just the SYS is flashing. What components are controlled by the CCM? If this is a huge list then generalities like "fuel system" are fine.

kwik_ta

Send a PM to Bogus... he is the guru for things like this

Jet-Jock

The CCM is the master computer. It works in the same fashion as a client-server in which the others are constantly talking to the CCM, if one of them doesn't report in a specified time period a DTC is set. I can look the time period up if you wish for that detail.

Back to the SYS lamp. Since it is only your SYS and not both SYS and SECURITY then we can eliminate FEDS from having enabled itself.

With regards to SYS lamp, if while operating you get a SYS lamp flashing, it means a current DTC is present now. If you pulled DTC's you'd see the code with a C in front of it. If you cycle the ignition and what was causing the condition is not present meaning its not setting a current code the previous code is still set, however when you pull DTCs again you will see if now has an H in front of the code meaning it is historical.

So while the problem is occuring, the SYS lamp will flash. If it was intermittent or not occuring at the present moment the SYS will not flash, but the code is still present and can be retrieved.

If you had no DTCs set and pulled CCM DTCs you would get a C12 meaning at the present there are no DTCs. You would not get a H12, that would be silly meaning at some point in time there were no codes.

Sometimes when a current DTC is ongoing it can prevent it from starting depending on the DTC. At this point you need to pull codes from the CCM. I only have info on ODB-1, I'm still looking for the ODB-II, Bogus should probably have this info in a pdf. You may PM him to get access to it.

Don't suppose you have the Helm service manuals?

sremenap

ok.

The manuals i do not have, but i am looking into getting a set.

This car is ODB1 i believe, ODB2 didnt show up until 94/95 area. I cannot even pull codes, because when the SYS light is flashing, it will not even throw codes for me. It is very much like the car is having and epileptic seizure.

Jet-Jock

I'm really going out on a limb here because I don't know for certain what a 91 has. Regardless when you access the diagnostics it should have no relationship to the SYS lamp. As I mention that is telling you have a current code.

Here's an image of the pin out of the DLC. Now if yours is the same, you should be able to jump the pins and pull codes. I have a complete pdf if you wish to review it.



Quickly the procedure would be:

- Have a piece of paper and pen ready
- Ignition OFF
- Remove the DLC cover.
- Using a large paper clip not the normal small one, and you'll probably need a flashlight to see well, insert it into Pin A and G.
- Turn the ignition switch to ON.
- Write down the codes as they are displayed.

The display will switch to diagnostics mode.

At first it automatically runs through all three modes then returns to the state of waiting for a command in which you can review them module at a time.

So you might see something like "1.1 C41 H28, 4.1 12, 9.1 H21"
1.1, 4.1 and 9.1 are the three modules for the three computers.

Here's a link to the pdf to explain it in more detail.

Pulling codes

Now this is for 92-93. Which is why I cautioned you about system differences. Perhaps someone with a 91 will chime in and help.

Once you have the codes, turn the ignition OFF and remove the paper clip jumper. Let us know what they are.

sremenap

remember i am talking about a SYS light on the digital dashboard - not the SES light on the driver console.

On the 91 i get my codes from the SES light, and i have a code reader i can plug into it.

The SYS is next to the fuel reading on the digital speedometer.

Jet-Jock

Yes I'm aware of that. SES is also referred to in the service manuals as MIL. Does yours have the later C4 model display?

Yeah I'm trying to be real cautious here because I'm not that familiar with your year model. I wish I had the code reading info for all C4 applicable models.

What codes does the reader show?

sremenap

thats the thing - no codes.

I believe mine is the later C4 display.

JrRifleCoach

Yes, but did you try to use the old fashion way and jump the ALDL to read the flashes?

sremenap

thats what the reader does - it is a glorified paper clip. It just gives you the option of jumping it to see the ECM, or ABS codes with a switch.

same deal.

Jet-Jock

Sorry don't mean to disagree, but you should at least consider a fault in the reader or its interface and at least give the onboard system a chance to confirm the results. At least that way you can say I'm getting a C12 no codes from both systems. Just a thought.

From before, at the 90 year model the new dash came onboard.



The reason I asked, with this dash style the MPH display changes to the CCM diagnostics reader/enabler when pins G and A are jumped.

You get all three diagnostics from the CCM, however you can get ECM from the DIC panel. ECM by interpreting the number of flashes of the SES lamp when pins A and B are jumped.

sremenap

ok - when i say i am getting no codes, i mean getting no fault codes - i get the 12 code. And the only place i know to get codes is the DIC - i have never gotten codes, or heard you could get codes before now, from the Digital MPH display.

Sorry i was ambiguous. That dash is my dash.

Jet-Jock

I'm not sure where else to point you. The SYSTEM lamp flashing means you have a current code. Originally you said it would not start. Is that still the case?

If your DLC looks like the image I posted and no other 91' owners have chimed in you can always try jumping the pins and see what the results are. If you get a C12 then its back to the starting point (no pun intended).