I have a 92 Z-28. After about 15-20 minutes of driving, sometimes my check engine light comes on. I don't particularly push it, usually it happens during a highway cruise, but it doesn't always come on. I'm at almost 120000 miles. Can anyone explain?

 

your computer is setting a code. take it autozone they will read it for free and tell you what code it is setting. sick

 

Thanks

 

The light will go out but there is still a problem present.
jump the two black wires on the aldl connector, turn the key on and count the flashes and spaces.
it will flash code twelve first.
One flash (pause) two flashes (pause) (repeats two more times as it does with all the codes)
code twelve is nothing it just does that to let you know its in diag mode.

 

While were on the topic, i ran a code reader and got code 24 which is for the VSS (Vehicle Speed Sensor); Which explains why the speedo doesnt work in the morning; this is dangerous because In my small town of 10000 peeps we have 100 cops with nothing else to do but catch people going 37 in a 35mph. anyways I should probably get that **** fixed, so does anyone know where the VSS is located/ What it looks like? The Chiltons didnt help. Thanks

 

On the older mechanical gauges it was on the back of the speedo and tach. I think on yours it is where a speedo cable goes into the trans. There is an electrical plug there now and it send signal to the computer.