P0480

P0480 sets when the PCM detects a fault in the control circuit for cooling fan relay 1 -- either the relay coil is open, the PCM ground-side driver cannot pull the coil low, the 12V coil feed is missing, or the relay is shorted. On most modern vehicles the PCM grounds the relay coil to energize it, while a constant 12V feed (usually from an ignition-switched fuse) sits on the other coil terminal. Cheapest first, and this is the cheapest of all the cooling fan codes: pull relay 1 from the underhood fuse box / TIPM / PDC, inspect the terminals for heat damage or pin push-out, and swap it with a known-identical relay (horn or A/C compressor relay is usually the same Bosch/Hella micro-relay part number). Clear codes and retest -- if the code stays gone, you spent $0 and 10 minutes. If swapping the relay doesn't clear it, key-on and back-probe the two coil pins at the relay socket: one should have 12V (the feed), the other should sit at 12V at rest and pulse to near 0V when the PCM commands fan on (you can force fan-on with a bidirectional scan tool, or by raising commanded ECT). If the 12V feed is missing, trace the fuse and the splice. If the feed is present but the PCM-side ground-control pin never pulls low, the PCM driver is failing or the wire to PCM is open. Caveat: cooling fan circuits are the single most common false-failure on GM TIPM-style fuse boxes (Chrysler/Dodge) and on integrated GM underhood bussed electrical centers -- techs replace fans and motors for $400+ when the actual fault was a $25 relay or a corroded fuse box socket.

Vehicle-specific patterns: 2008-2014 Dodge Grand Caravan / Chrysler Town & Country 3.6L Pentastar -- TIPM internal fan relay solder joint cracks, Chrysler TSB 08-001-15, recall later issued for repeat failures. 2007-2013 GMC Acadia / Buick Enclave / Chevy Traverse 3.6L LY7 -- underhood bussed electrical center (BEC) fan relay socket overheats and discolors the plastic, GM bulletin PIP4946. 2006-2011 Jeep Grand Cherokee WK 3.7L -- TIPM cooling fan low-speed driver fails internally, full TIPM replacement only. 2010-2015 Chevy Equinox 2.4L LAF -- fan relay control wire backed out of X50A PCM connector pin 44, GM PIC5784. Estimated repair: $25 to $620.