Engine cooling fans not turning on?

MKMOTORGROUP

MEMBER
2006 CHEVROLET AVALANCHE
5.3L
V8
4WD
AUTOMATIC
171,000 MILES

Low speed fans not turning on. I've checked all the relays, fuses. Hotwired the fans to make sure they work. Checked every wire from fan to relay box for continuity. Checked for power and ground. Connected my launch tool. Codes p0480 only. Control circuit 1. After that went into bidirectional and commanded to power the fans. Works only on fan command 1, 2 and 3. If I command to power relay 1, nothing happens. Also, the left fan will work at full blast with A/C on. Otherwise, it would go past 230 degrees and still not powering on. Tried almost everything. Just wanted to make sure if it is the computer or now. Thank you, guys.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,758 POSTS

Hi,

If the power supply is good, the relay is good, we have ground for the relay, and there are no wiring issues, it's time to start testing.

If you look below, I attached the directions specific to the P0480. There is a chance the PCM may have failed, but the directions need to be completed to make that determination.

Take a look through them and let me know what you find. I realize parts of the diagnostics have already been performed, but make sure all bases are covered.

Let me know what you find or if you have questions.

Take care,

Joe

See pics below.

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