GMC C1500 Computer Read Codes

Checked All The Fuses Bought A Cam Posisioing Sensor Undid The Ground On The Battery Thought It Might Reset Computer Didnt Find The Inline...

When The Ignition Key Is In "bulb Check" Position, Three Warning Lights Come On And Stay Constantly Lit: Service Engine Soon, Check Gauges...

I Heard There Was A Way To Use A Jumper Wire Instead Of Use An Accual Diagnostic Devise To Get Servise Codes For My Truck I Was Hopeing You...