Need routing diagram for the serpentine belt on 454 engine,4wd, automatic transmission.

Pick your choice based on what attachments your engine has hung on it, enter this into your computers browsers search box
"serpentine belt on a 1990 chev k 3500 454"

Go to this website and input your information, it is a Dayco site, that will show you the routing diagram. http://www.accessdayco.com/automotive#/1986

Hi, first, keep this diagram around as you will need it to route the serpentine belt when you reinstall it. There may also be a diagram under the hood by the radiator.
Next, follow this link and watch the video that shows you how to replace a serpentine belt...
http://www.wonderhowto.com/how-to/video/how-to-inspect-and-replace-your-car-s-serpentine-belt-267229/
Take care

Fig. Serpentine accessory drive belt routing-3.0L (VIN U) engine


Fig. Serpentine accessory drive belt routing-3.0L (VIN S) engine


Fig. Serpentine accessory drive belt routing-Ford 3.0L (VIN U) engines


Fig. Serpentine accessory drive belt routing-Ford 3.0L (VIN S) engine


Fig. Serpentine accessory drive belt routing-Ford 3.4L SHO engine


Fig. Water pump drive belt routing-Ford 3.4L SHO engine
i wasnt sure what engine you had hope this helps good luck

You didn't list your motor size so please pick the applicable diagram:


Accessory serpentine belt routing—4.8L, 5.3L & 6.0L engines


Accessory serpentine belt routing—5.7L engines with A/C


Accessory serpentine belt routing—5.7L engines without A/C


Accessory serpentine belt routing—6.5L Diesel engines


Accessory serpentine belt routing—7.4L engines


Accessory serpentine belt routing—8.1L engines

There are 2 engines for your Mazda 6, a 2.3 and a 3.0. Below are both diagrams:
2.3


3.0

2.0L Engines
See Figures 11, 12 and 13
The accessory drive belt for 2.0L engines has no provision for manual belt adjustment, since these engines use an automatic belt tensioner. Drive belt slack is taken up by the automatic tensioner.
Movement of the automatic tensioner assembly during engine operation is not a sign of a malfunctioning tensioner. This movement is the tensioner self-adjusting and is required to maintain constant belt tension.
The belt tensioner has a belt length indicator. If the indicator marks are not between the MIN and MAX marks, the belt must be replaced.
Fig. 11: Drive belt routing-2.0L SOHC engine with A/C Fig. 12: Drive belt routing-2.0L SOHC engine without A/C Fig. 13: Drive belt routing-2.0L DOHC engine

2.0L Engines
See Figures 11, 12 and 13
The accessory drive belt for 2.0L engines has no provision for manual belt adjustment, since these engines use an automatic belt tensioner. Drive belt slack is taken up by the automatic tensioner.
Movement of the automatic tensioner assembly during engine operation is not a sign of a malfunctioning tensioner. This movement is the tensioner self-adjusting and is required to maintain constant belt tension.
The belt tensioner has a belt length indicator. If the indicator marks are not between the MIN and MAX marks, the belt must be replaced.
Fig. 11: Drive belt routing-2.0L SOHC engine with A/C Fig. 12: Drive belt routing-2.0L SOHC engine without A/C Fig. 13: Drive belt routing-2.0L DOHC engine