First, I just wanted to say what an awesome forum! This is such a great resource especially for those of us new to Corvette ownership.

My service engine soon light came on and I've seen in other threads that you can pull the engine codes to find out what's up and was wondering how to do that?

 

See this link:



For best results when you have a question always mention the year of your C4, there is a lot of variation between 84 and 96.

 

If you have a laptop computer you can download free ODB disgnostic software from the Internet. You can purchase a ALDL cable for $65 to connect your Corvette's OBD connector (located under your steering wheel) to your laptop and read your codes. You can also use a paperclip to read the codes manually using the dashboard flashing method. See the attached write-up.

Let us know if you still have questions after reading the write-u.

 

Thanks so much for the help pmihaltian. I realize this has probably been asked before and I appreciate your taking the time to respond about this and including the attachments.

And for toptechx6, yeah, sorry, I'll try to remember to include the year in future posts.

 

This is the way I check codes on my '94.

On a 94-96 you can check the codes with a paper clip as follows:

You short pin "12" to pin "4" and turn the ignition switch to "On" without starting the engine.

The speedometer will display any codes using the same protocol as the 1990-1993 model but there are some changes in the designation for the modules plus additional modules are added:

Module "1" is still the CCM module.

Module "4" is now called the PCM module (Powertrain Control Module) because automatic transmission computer control was added to Engine Control Module in 1994.

Module 7 (on the 1996 model only) is the RTD module. (This is the Real Time Dampening module which replaced the Selective Ride Control module in 1996).

If you would like a listing of the codes please let mw know,

Module 9 is the ABS/ASR module number from 1994 through 1996.
Finally, Module "A", the DERM (Dynamic Energy Control Module --- (the air bag control module) will be requested to show any codes.

Just like the 1990-1993 display, you read the codes on the speedometer (big) and read the module number on the trip odometer (small).

A series of dashed lines for instance “ - - -“ indicates no more stored codes for that module.

A code showing as “C12” for the CCM module (module #1) means no codes are stored. So C12 is a good thing to see.

Again, you can cause the codes to repeat by turning the ignition off for five seconds and then back on.

Turn the ignition off and remove the short to restore normal operation.

To clear the codes,

1. With ignition "off" ground terminal #12 of the DLC (use bent paper clip to connect pin 4 to pin 12)

2. Turn ignition "on".

 

Looks like I have low manifold air pressure. What causes this and how do I fix it??????? Mine's an 87.

 

What code did it show? If it was a 34 the low manifold pressure error is for a 1984. 34 for an 87 would be for the MAF.

34 Mass Air Flow Circuit (1985-1990)

34 Manifold Absolute Pressure Low (1984)

 

Hmmmmm, OK, looks like it's the Mass Air Flow Circuit. So, what's the up with this and thanks for taking the time to help out with this.

 

http://members.shaw.ca/corvette86/Code%2034.pdf

 

Great thread!

 

as a junior member and first time vette owner... there are several in here that are extremely helpful and it is much appreciated. al