1988 Service Engine Light On
 

My 88 has 6600 miles and obviously doesn't get driven much and I'm the original owner. Service engine light has been coming on for quite some time but because I don't drive it much I've let it go. What do I need to find out what code is in memory? Should I take it to the dealer or is there some way I can find out what's wrong and then decide whether I need the dealer to fix it. I should mention I try to change the gas out each year but sometimes it gets smelling like varnish, could that be the problem, someone told me it was probably the O2 sensor but I'm lost. Sometimes when I drive it kind of hard the light will go off but it's soon back on after car sits for a while. Thanks for any help.

If you have a laptop computer I'd recommend Tunerpro (Free) and a USB ALDL cable @$60. Much more powerful than a handheld unit and much easier to review your logs after the fact. Another choice for reading the ALDL datastream is WINALDL. You will still need a ALDL cable but this will also allow you to read codes, and datalog the info using your laptop computer as well.


http://tunerpro.markmansur.com/
http://winaldl.joby.se/
http://ALDLcables.com/


Good Luck! :thumbs:

See this link for a way to retrieve the Diagnostic Trouble Code using just a paper clip. For best results troubleshoot any DTC's using the correct Factory Service Manual for your vehicle or post them here and someone should be able to advise.

http://tinyurl.com/2e5abh3

:iagree: Paper clip works well

I have diagnostics for each code on one of my sites.

http://members.shaw.ca/corvette86/

Thanks, this is the kind of help I was looking for. I will check it out.

I tried the paper clip trick and got error code 42 so now I'll be checking out the electronic ignition module wiring hoping to find a loose wire or bad ground.

Bad knock sensor ???

You know that from error code 42? I thought this had something something to do with electronic spark timing.

Bypass Connector left disconnected after last timing adjustment?

Sorry, I misread your post as code 43. Follow Ray Quayle's advice. :thumbs:

With 6600 miles I'm not sure there's been a timing adjustment or if so its been quite a while but where do I look for the bypass connector? Obviously showing my ignorance but can you point me in the right direction, thanks.

Then this probably isn't the case, but often this is forgotten after a tune-up/timing adjustment and it is a quick and easy check that can cause a code 42. It is a single place connector, a tan wire/black stripe. Should be between the driver side valve cover and brake booster/master cylinder coming out of a wire bundle.

I checked and don't know for sure if I know exactly which wire you're talking about but there isn't any loose or disconnected wires in the area you mentioned. Does it plug up into the drivers side of the distributor? Another question, if I purchased the cable to connect from the diagnostic plug to my laptop would I get more info that would help identify the problem or would I just find out the error code 42?

Here is a photo of the connector. See the attached write-up for additional details. You should have a Factory Service Manual if you plan to work on your Corvette yourself. In the mean time take a look at the Code 42 PDF that Agent86 sent you.

My recommendation is that you should invest $60 in the ALDL connector and the free ALDL diagnostic software. While it will not tell you how to solve your problem (use the FSM for this) it will make it a lot easier to get your error codes than fiddling around with a paper clip and trying to count flashing lights.

Well it's been 9 years since I last reported this problem and now I've got 7248 miles on my 1988 Corvette convertible. I want to see if I can track down the problem causing my intermittent "check engine light" code 42. Where is the ignition module located, is it under the dash on the passenger side? Any help is appreciated. Thanks.

Sounds to me like you need to find a local shop that specializes in Corvettes or bring it to your local Chevy dealer.

I will assume at some point in the 9 years the battery has either dies or been disconnected... did the code go away and come back? If not, try it.

Code 42 is a frustrating one as it can have multiple causes in the ignition circuit.

https://cimg2.ibsrv.net/gimg/www.cor...aa1b6f78da.jpg
I believe the 88 Corvette's still had the coil in cap system. This exploded view should help you locate it. You can take the ICM out and have it tested at your local Auto Parts chain store of your choice.

Indeed that Tan/Blk wire is one of the wires coming out of the LH side of the Dist. If you open the wire bundle into which it runs you will find the connector that must be opened to set base timing.

The ECM is located under the RH dash. To access/drop it remove the hush panel, remove the two screws under the panel edge and lower the ECM.