You Must take the exhaust off at the manifold.
The signal and 4-way flashers are located behind the lower dash panel, aprox under the radio. The plastic lower dash panel must be removed to gain access to the flashers.
The spark plugs in a 2003 GMC Sonoma can be changed relatively easily with a socket wrench. However, the spare wheel must be removed from the wheel well to allow access.
If that is the Northstar engine, the intake manifold must be removed to gain access to the starter.
It is above/behind the starter. The starter must be removed in order to access the sensor to change it.
The starter is located under the intake manifold in the rear center of the valley. The intake must be removed to gain access.
The first thing to do is check the starter relay which is below the motor. If that doesn't work, the starter must be completely removed and replaced.
It is inside the bellhousing. The transmission must be removed to gain access to it.
If you are talking about the ignition lock cylinder, the steering wheel must be removed and the column disassembled to access a lock screw which holds the ignition lock cylinder in the column. No key is required for this (unlike all other vehicle manufactures). If you are talking about the door lock cylinder, the door panel must be removed, and the lock cylinder retaining clip must be removed (again no key is needed, which is the same for all manufacturers). If you are talking about the trunk lock cylinder, it is easily accessible from inside the trunk. Those are the only types of lock cylinders in this type of vehicle. There is no specific lock cylinder named key lock cylinder.
on a 5.3L it is behind the starter that must be removed first
you must remove the clutch slave cylinder and line. Then unbolt the starser and install the new one
Under the intake manifold Between the top intake manifold and the engine block. The top intake manifold must be removed to access the starter.
To replace t starter on a V8 Touareg, the engine must be removed. It is not something most people would be willing to tackle on their own.