I have posted another thread, and searched for days with no answers.
My problem is that I have an SES light coming on intermitently, and when the light is on the engine has a really bad hesitation above 2000 rpm. Now i know it probably needs a tune up, but I don't think that would explain it only happening sometimes. And also there are no codes being thrown either.

 

If theres a SES light coming on, then theres a code stored. The light goes out if the ECM thinks the problem has fixed itself.

The very next time it comes on, immediately stop and pull the code. Until then, dont do anything.

 

No codes, eh.

First, do you have the Factory Service Manual?, If you do, head for the Driveability and Emission section, review the appropriate section for stumbles, misses, whatever you think is most appropriate for your situation.

Couple of points. Understand you have tried to pull the codes. Did you get solid 12's? As I understand it, there may be been some 95's that need a scanner. Believe that one has the OBD2 connector.

There are some conditions that a SES light will appear and not store. That is why a review of the appropriate service manual is important.

As a general note, hesitations at RPM are usually fuel or ignition. If you have a fuel pressure tester, I'd check the fuel system pressure, and do a fuel flow volume check. The service manual will list many test for this type of problem. If you are getting the SES, then something is obviously exceeding a parameter.

Sorry I couldn't have been more helpful. Someday I'm going to buy a C4 service manual for each year.

dlmeyers 90 coupe zf6 3speed shocks

 

thanks, I don't get just straight 12's but some old history codes H71,H72 that really don't relate to this. Don't know how to clear those. Other than that I just get the 3 dash lines.

 

I still haven't seen a question...ASKED. Were you planning on posting the year of the car you're concerned with?

Step one: Get a factory service manual. Beside telling you how to extract codes and decoding their origin, it will give you certain procedures. Besides valuable troubleshooting charts, it will likely advise you to clear all the old codes (and even tell you how) before looking for new codes. In fact, I'll bet one of the last steps in a procedure is to clear all the codes, so that someday, down the road, if the SES light ever comes on, the codes present at that time will have some significance. If it doesn't, common sense would dictate that.

RACE ON!!!

 

How is what I posted not a question? I have a problem this is what is going on. hmm? And it is real easy to find the year in my profile dlmeyers did, isn't that the point of the profile. I don't have the extra cash to buy a $50 book, these repairs are going to set me back as it is, so I'm getting a little tired of that answer. As soon as I have extra cash I will for sure buy the book, but until then I would like to have my questions answered with something useful, not maybe you're low on brake fluid, or your gas cap isn't on tight. I have noticed a definte downfall in the members here helping out others. Thanks to those who have posted some helpful info.

 

-disconnect your -ve battery terminal fo 30 seconds. this will clear your error codes.

 

How is it? What is it? To this point, this is the only question asked.

And this is the second, and only other question, despite the lack of a question mark. I don't Google, do a search, or do a back ground check on everyone I may attempt to advise. How hard is it for you to post the pertinent, relative, information along with the symptoms? How hard are we to search for your info? How badly do you think we NEED to provide assistance?

The expenditure for the book, probably double your estimate, isn't a luxury for "someday". It is a valuable tool to help you repair your as quickly and economically as possible. Without it you are likely to replace good components that aren't the cause of the problem. A logical, methodical path of organized troubleshooting and parts testing will get your problems solved the cheapest way.

There is a downfall, also, of people that expect help that A) don't ask, and B) for one reason or another, are too lazy to help themselves. Then that have the stones to carp about the quality of the well meaning, free advice. If you had read your manual, some of those seemingly "silly" answers may have more basis in fact than your ignorance can imagine.

RACE ON!!!

 

I'm kind of with CFI-EFI on this one. Your first post you could have put, "I have a 19XX Vette, seeing ses light, used a scan tool to check for codes and there were none." You see, if there is even an intermittent ses light the computer will store the code for later retrieval. Your first post says essentially what I have in quotes, but not quite clear enough. Also, by stating the year of the car we could tell you how to clear the codes. I agree that we shouldn't have to go looking at your profile to find out the needed info. And, nobody anywhere is going to solve your problem on a forum without you putting some time and money (service books, scan tool, fuel pressure guage, etc...) into the solution. I've gotten some great help around here, amazing help actually, but I've also spent lots of my own money along the way. Good luck. Post back with more info on this problem so we can try to help. Does unhooking the battery clear H codes from a '95? I dunno. I do seem to recall that some '95's (maybe all) had the obd II connector under the dash even tho they were actually obd I cars. OBD II for sure you cannot clear codes by unhooking the battery, you need a scan tool or code reader with reset capability.

 

Thanks for the info on the battery, I was hoping to do it without reseting everythough though.

Everyone else here seems to understand that I asked a question, just because I didn't put a question mark doesn't mean anything, sorry but this is not grammar school.

No one ever said you need to do a backround check, all you have to do is look to the left there is a button you can click that will give you a whole profile, not very hard, I do it all the time. Do you have to help others? NO. But then what would be the point of the forum.

Add more to my point a $100 book, even more out of the question at this point in time.

Lets see I posted that I have done a search I have asked the question before with no help, and I have already done what others have advised. Hmm brake fluid does not make a car run rough no matter how you slice it, and a loose gas cap maybe, but that is something you do everytime you fill up, so if you want to call me ignorant, and spend more time arguing with me on little nit picking crap, and not help me or others who are here looking for honest answers not english lessons.

 

You got an H71 and H72 code? Is that possible? I tried to do a code lookup on my scan tool for those on a '95 Vette and it wouldn't let me.

 

Thanks, yes it would be just as easy to post, but once in a while you forget and it is not that hard to look real quick if you have a real interest in helping someone, I have also gotten great help in the past, recently not so much, seems like most everyone is in a bad mood. Your post did not seem so threatening. I have spent money on my own car, more than I would like to, and I have gone out of my way to help others in areas that I do know information, my financial situation right now does not allow me to spend much money just what I need to in order for my to get down the road. And yes my car has the OBD2 connector.

 

I had those codes a long time ago and a previous member told me they had something to do with a ground on the dimmer and something else along those lines, thanks.

 

H means the error code is a History code and no longer exists.

DTC 71 LCD Dimming Circuit Shorted to Battery Voltage or the CCM circuit is bad.

DTC 72 LCD Dimming Circuit Open or Shorted to ground.

Basically what happens is the CCM monitors the circuit.

1) Ignition is on
2)Head lamps or Parking lamps are on
3)The Dimmer on the Headlight switch is not set for 0% or 100%

DTC 71 sets because the CCM does not see the signal line go Hi over a certain time frame.

DTC 72 sets because the CCM sees the signal stay low for a certain time frame.

The manual says possible causes are bad connections at the CCM connector, Radio Control head connector or the connector on the back of the A/C Heater Control Head.

This is what was posted by another member, I just now ran the car, and when the SES light comes on at idle the rpm go up about 200 and the cooling fans kick on. While the SES light is on the car has no power when you get on the gas, but rev's freely while parked. But when the light is off, it's like there is nothing wrong at all. So is there anything that could cause these symptoms without storing a code, and only be intermittnet?

 

Brich, I think you're a little confused w/ the troubleshooting procedure...I can't speak with 100% certainty to your 95, because I have a 90 but the procedure should be similar..... You have an SES light on when the car is down on power, but the codes you are pulling are CCM (BCM in your case) codes...BCM codes do not flash an SES light, they are indicated by "SYS" in your dash display..SES lights are ECM-PCM related....Two different systems..Problems in the dash should not cause a power loss...Let the dash display cycle past the first codes until you get ----, then read any codes flashing in the next module #4 ( these are numbers on 1990), these are your SES codes...Do this when the car acts up as Vader said and you should get an idea of where your problem is...

 

1- yes, the majority of '95's have OBD2 connectors, but all '95's are OBD1 compliant. So if u have an OBD2 connector, you just short pin4 and pin12 and turn on ignition and read the codes on display.

2- yes, disconnecting the battery on any '95 WILL clear your error codes. This is not up for debate, I've done it many times on my '95.

3- i rarely ever purchase FSM's for my cars, mainly 'cuz i usually sell my cars after 1 or 2 years. So for me, buying an FSM is not cost effective. IMHO, the information which i can obtain from Forums like this, and the many other Web sources is far more useful than any FSM, but you have to be savy enough to weed out the BS. But for all you believers of FSM's....I salute you for sharing your info. with me over the years..

4- if an SeS starts flashing, momentarily or continuously, an error code should be stored.

 

Maybe grammar school is where you ought to be. Please highlight , mark, or quote which sentence, question mark or not, that contains the question.



And all YOU have to do is A.) Use your year in your screen name; B.) include it in your avatar; C.) your POSTED signature; or D.) Simply, out of common courtesy, mention it in the text of the post. It makes a lot more sense to insinuate that *I* am lazy, because *I* don't want to go to the extra effort to do YOU an even larger favor by looking for what you could have, and should have, provided, with less effort.



It is likely, if you haven't done it already, that you will WASTE money on this repair that could have gone to buy the book that would have saved you the money.



I HAVE tried to help. Reread my first post. Ignorance is a state of knowledge. If you haven't studied a factory service manual, and don't know how the gas cap ties in, then that is ignorance. That is not name calling. It is a statement of fact. If you don't like the facts...CHANGE THEM. You are going to have a tough time learning anything, while you still know it all.

RACE ON!!!

 

BRICHC4,
Do your best to listen to CFI-EFI, or at least pay attention to what he is saying. His knowledge will get the problem solved for the lowest cost. Nobody wants to spend money on wild goose chases.

When you ask for help, it’s always wise to do your best to help others help you. If the person who has the knowledge to help you needs to “dig” for too much information, they may not offer.

In this case CFI-EFI is trying, even if you don’t think he is. Even without actually helping with your Corvette problem, he is giving you some excellent advice for your future issues

 

exactly, there aren't any codes being stored when the car is down on power, the codes present are non-related. I have let it run through all the modules and all I get are ---.

 

I did use the 4 - 12 pin, and thanks on the battery disconnect, I'll do that, and you have to do that when the car is not running correct? so then are you able to use a scanner when the car is running, so I can read when the light is on?