Dear friends, I hope that you can help me, like other times. Thanks in advance for your time and support.

I have a 1988 C4 Corvette. When I purchased it, EGR temp sensor was DISCONECTED, I mean the wire was not attached where it was supposed to do so.

Due to some emmission problems, a year ago I replaced the EGR valve and re-connected again the temp sensor.

Emission problems persisted, so few weeks ago I replaced also the O2 sensor and the EGR solenoid.

At first, no problems, but TODAY, just few seconds after start the engine, the Engine Service Soon light turns on.

So, considering that my car does not have ALDL and I can NOT read codes from ECM, what do you thing that can be the cause?

1) EGR temp sensor switch is the problem from the beginning. Previous owner disconected it just for this. But then, why the SES light turns on only now? I have used the car during a year with the sensor re-connected with no SES light. Can be due to the recent EGR solenoid replacement, that affects the temp sensor readings in some way?

2) It must be one of the last parts replaced by the mechanic: EGR solenoid or O2 sensor. Maybe some contact, or bad connection. The strange thing is that I have driven the car four or five tims since then with not SES light.

3) Can be coincidence, but another part needs to be replaced, for example the MAF sensor.

The only clue that I can provide is that the light appears just after few seconds from start the engine, and at the moment the car has low gas and it has not been started from more than two weeks. Performance and RPM seem normal.

Any idea???

 

Your '88 should have ALDL : http://www.corvettebuyers.com/c4vettes/codes.htm

 

I tryied to search for it it he past and it was missing. Not ALDL, so the community is my only diagnosis tool ;-)

So, any suggestion regarding the Service Engine Soon light?

 

No connector, no bundle of wires, no nothing ?

Maybe another look is in order, otherwise, guessing the code will not be helpful.

Where were you looking ?

 

Did you pull down the hush panel and make sure it's not in there?

 

I have heard of people who found the ALDL connector stuffed in behind the HVAC controller. For some reason people unbolt it from its normal mounting place and then put it inside the dash to get it out of the way.

 

Yeah that connector is there somewhere. As said above, remove the hush panel and it will probly fall down in your face.

 

Ok, I'll try to search for it, but, according to what I tell you, do you have some suggestion about the cause of this SES light?

 

 

To find out what the SES light is trying to tell you, see here:

http://corvettephotographs.com/c4vettes/codes.htm

 

We will all be shooting in the dark with diagnosis until you get the codes. There isnt really any way to check the components that I know of.

Have you pulled the hush panel off yet?