1998GMC SIERRA stock amp location - 1998 GMC Sierra

I would suggest you spice the wires back to stock harness by male and female connections and tape over them with black tape then get a stereo install kit that includes a wiring harness ( cost about $20 maybe or less) for the year of truck you have... it will plug right to your stock harness ...never just cut stock stereo wires from stock plug it will be more of a headache than you think trust me I've installed all my own stereo system been there done that... good luck

Under the seat most time back pass if u got a back if not try front pass side good luck

Two wheel drive? Remove driveshaft,flywheel cover, three bolts from flywheel to converter, disconnect trans. lines from case, cable, harnesses, trans. bolts.

most times either attached to the backside of the radio or somewhere close by behind the stereo in the dash

use a scanner to help you identify the problem. You have identified the fuel injection system as being the problem by introducing has into intake during cranking. The fuel injection is signaled by the crank and cam position sensors. check for dirty or loose connections at these sensors.

http://troubleshootmyvehicle.com/gm_fuel_injector_4.3L_5.0L_5.7L/spider_fuel_injector_1.php

most 03 sierra's don't have one

Not sure I understand your question. Did you buy a harness adapter for GMC, or are you trying to just cut the connector off the factory radio and solder it to your CD player? If the latter, below is the color code for your factory wiring.

1994 GMC Sierra C1500 Car Radio Wiring Schematic
Car Radio Battery Constant 12v+ Wire: Orange
Car Radio Accessory Switched 12v+ Wire: Yellow
Car Radio Ground Wire: Black/White
Car Radio Illumination Wire: Brown
Car Stereo Dimmer Wire: Gray
Car Stereo Antenna Trigger Wire: N/A
Car Stereo Amp Trigger Wire: N/A
Car Stereo Amplifier Location: N/A
Car Audio Front Speakers Size: N/A
Car Audio Front Speakers Location: N/A
Left Front Speaker Positive Wire (+): Tan
Left Front Speaker Negative Wire (-): Gray
Right Front Speaker Positive Wire (+): Light Green
Right Front Speaker Negative Wire (-): Dark Green
Car Audio Rear Speakers Size: N/A
Car Audio Rear Speakers Location: N/A
Left Rear Speaker Positive Wire (+): Brown
Left Rear Speaker Negative Wire (-): Yellow
Right Rear Speaker Positive Wire (+): Dark Blue
Right Rear Speaker Negative Wire (-): Light Blue

sounds like the accuator is bad , it cost 65.00 at auto zone and an easy install!!

any tire dealer can provide this info.

There is a Relay for these in the Fuse Box under the Hood. Replace that Relay and you should be Good.