Behind the drivers head there is a clamp that holds the oxygen sensor harness. It is bolted to the back of the head. this clamp is sharp metal and shorting your oxygen sensor heater wire to ground and blowing the fuse and causing a million codes. You're f'ing welcome.

 

Can this clamp be accessed from beneath the truck? and can you elaborate on the "head".

 

Behind the drivers side cylinder head. Actually by 03 they wrapped the clamps better. so yours may be a bad oxygen sensor heater.

 

Might also check the wiring for the cam position sensor on the front of the engine. The wiring runs behind the bracket for the power steering pump, and can get chaffed.

 

Regarding the blown 40 amp fan fuse, your electric auxiliary fan motor is most likely seized up. Pretty common failure, happened to mine as well. Not a major issue this time of year where you live, but you should investigate it further when you can.


Also, the harness running to the pass. side secondary O2 sensor sometimes rubs through above the frame rail where it's routed around a pipe for the evap system. If nothing else mentioned here turns up anything then check there as well.

 

By auxiliary fan are you referring to the big cooling fan that's positioned between the radiator and the engine? If so I know its still working. After I replaced the fuses I double checked to make sure the fan was still spinning and it was while the engine was idling.

 

No, that's a mechanical fan that is driven by the engine. The auxiliary fan is electric and is behind the grill, mounted in front of the radiator and condenser.

 

So your saying that this fan is linked to fuse #2 or fuse #5? And how do I confirm that the fan is seized? When does the aux fan typically move? All the time while the vehicle is running or only when the engine tempatures reach a certain degree?

 

The 40 amp fuse is the fan fuse, sounds like it's fuse 5. Separate issue from your other issue with the blown 15 amp fuse related to your check engine light codes.


The aux fan only cycles on at higher engine temps, I believe its when the coolant temps hits 210 if I recall correctly.


If you want to check out the fan, remove the grill and then the fan and see if it will turn by hand. Should turn freely, mine was pretty well stuck.


Honestly I would probably fix the short causing the check engine light first, then tackle the fan issue later. In cold weather it's not that critical. Not that you shouldn't fix it when you can.

 

or unplug the wiring to the fan replace the fuse and see if it blows.