The speed sensor is located in the fan clutch. The fan clutch has a eletrical harness that goes to it, its controled by the engine computer. You may want to check the wiring going to the fan clutch to see if there is any damage, but most likely you will have to replace it. The wiring harness is located on the drivers side top of the radiator
. To replace the clutch, you have to take off the fan shroud, its a tricky job on this truck and you can damage the radiator if you are not careful. You will also need a fan clutch wrench to take it off the water pump
Here is a bulletin for GM on the code. you can inspect it, if there is no damage, then you need a new fan clutch, not a cheap part or repair.
#05-06-02-012B: Service Engine Soon (SES) or Check Engine Light On, DTC P0480, P0526/P1481/P1484 Set (Replace Engine Cooling Fan Wiring Harness) - (Oct 19, 2006)
|Subject:||Service Engine Soon (SES) or Check Engine Light On, DTC P0480/P0526/P1481/P1484 Set (Replace Engine Cooling Fan Wiring Harness)|
|Models:||2004-2006 Buick Rainier|
| ||2002-2006 Chevrolet TrailBlazer, TrailBlazer EXT|
| ||2002-2006 GMC Envoy, Envoy XL|
| ||2005-2006 GMC Envoy Denali, Envoy XL Denali|
| ||2002-2004 Oldsmobile Bravada|
This bulletin is being revised to add DTC P1484. Please discard Corporate Bulletin Number 05-06-02-012A (Section 06 -- Engine/Propulsion System).
Some customers may comment that the Service Engine Soon (SES) or Check Engine light is illuminated. This condition may be intermittent and upon investigation, the technician may find either DTC P0480, P0526, P1481 or P1484 set.
This condition may be caused by the cooling fan harness chaffing against the plastic guide it routes through. This contact may damage the insulation of the wires enclosed in that harness.
Replace the engine cooling fan harness using the procedure listed below.
- Remove the cooling fan. Refer to the Cooling Fan and Shroud Replacement procedure in the Engine Cooling sub-section of SI.
- Place the cooling fan assembly on a bench.
- Disconnect the harness electrical connector from the cooling fan clutch.
- Remove the harness from the plastic guide while feeding the wires out of the slot.
- Before installing the new harness, wrap the affected area on the wires with electrical tape to keep the protective sleeve in place. Be sure to keep the tape approximately 25 mm (1 in) away from the connector so the wires can be fed into the slot.
- Feed the wires into the slot and install the harness to the plastic guide.
- Connect the harness electrical connector to the cooling fan clutch.
- Install the cooling fan. Refer to the Cooling Fan and Shroud Replacement procedure in the Engine Cooling sub-section of SI.
Harness Assembly, Engine Cooling Fan Wiring