Check engine light problem

[kingskippy2001]

I have a 1990 FULL size Chevy Blazer. It has a stock TBI350, 700r4 and a stock tc. I have a 6" suspension lift, 38" TSL's. I know my gearing is off some so I run it in drive instead of overdrive. Everytime I drive it for more than about 5-10 miles I get a check engine light. Any idea what that is?? I have also noticed a sensor (I THINK) hanging fron the driver side of the tranny/tc area. Is that a speed sensor?? What does a speed sensor look like? What does it do? Do I need it? If so how do and where does it go? Thanks for any help you may give.

 

[Thunder]

You need to check for trouble codes to find out what is wrong.
Does your speedometer work. If not that may be the VSS that is dsconnected.
If you dont Now how to check for trouble codes heres how:http://www.troublecodes.net/GM/
The data conector is under the dash next to the steering column

 

[dsmd58]

i hope im not hijacking when i ask what gears are you running? why do you say you need to run in drive and not OD? i just put 38's on my rig with 4.56 gears, do you know of a problem that i dont?

 

[kingskippy2001]

I only have 3.73's in it right now. I need 4.56 like you have.