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Code P0480


Tooler
02-23-2008, 09:08 PM
2004 Buick century,service engine lite on-P0480=cooling fan cotrol circuit malfunction, what and where should I be looking for the problem,Thanks

BNaylor
02-25-2008, 02:00 AM
DTC P0480 is a Cooling Fan 1 Control Circuit malfunction. This DTC sets when the PCM module output driver for that circuit fails the electrical integrity test. Meaning you could have a bad PCM module or maybe something causing a short on the output to Cooing Fan 1. Pull the Cooling Fan 1 relay in the main engine compartment fuse box, reset/clear the DTC, and then see what it does.

Tooler
02-29-2008, 03:30 PM
DTC P0480 is a Cooling Fan 1 Control Circuit malfunction. This DTC sets when the PCM module output driver for that circuit fails the electrical integrity test. Meaning you could have a bad PCM module or maybe something causing a short on the output to Cooing Fan 1. Pull the Cooling Fan 1 relay in the main engine compartment fuse box, reset/clear the DTC, and then see what it does.
Ok I found fan number 1 was burnt up,put a new one in,(new not rebuilt), cleared the code but it came back on,code PO480,i disconnected the feed at the fans,4 wires going in,2 wires going out to each fan, connected wire from battery,fan number 2 turned like it should,when I touched the wires to fan number 1 all it did was spark like a dead short,fan wouldnt turn, reached in and furned fan by hand,rolled easily,looked in the book,(wireing diagram),it shows there are 2 diodes conected,one for each fan,could one of these diodes be faulty and cause a short, now I dont know if the diodes are in the wireing harness from the connector to the fans or if their on the car side, if it aint the diodes then I suppose I got a dud fan motor,but it was brand new,i wish I would have tested the motor before I put it in.

BNaylor
03-01-2008, 11:25 AM
If you have the diode it should should be located in the wiring harness towards the primary cooling fan. As far as diodes in the circuit what documentation are you using?

Tooler
03-01-2008, 06:13 PM
If you have the diode it should should be located in the wiring harness towards the primary cooling fan. As far as diodes in the circuit what documentation are you using?
Update.
Disconnected the wireing harness, 4 terminal plug, 2 wires go to one fan,other 2 wires go to other fan,unplugged both fans,took the harnnes out,put ohm meter on the no-2 side wires,no continuity,(this fan worked) did the same with no-1 fan wires at the plug,had continuity on the meter,there is a diode on each set of wires ,if I dont have continuity on the no-2 side then I should not have continuity on no-1 side either, anyway I cut the rubber coating off the wire were the diode is embedded,one end of diode is connected to the + wire and the other end of diode is connected to the -wire,when I seperated the 2 wires,(they werent shorted out) the continuity on the meter dissapeared,the diode was still connected between the wires,I rolled the 2 wires around between my fingers and sometimes I had continuity and sometimes no,I found a place with no continuity and taped the wires up,again checking and no continuity so I plugged the leads into both motors,ran 2 jumper wires from battery, checked no-2 motor,ran as always,checked no-1 motor,now ran just like the other, thought it shoud be fixed,plugged the connector together,cleared the code(PO480) with my scanner,stared the car,drove it back and forth,everything normal,no service engine light,this morning, started car backed up and he engine sevice light came on,put scanner on,got PO480 again,cleared code, started car, drove 50 feet,engine service light came back on, I am thinking now its the diode thats faulty, what are these diodes for on each fan motor for anyway, fan no-2 is for AC and no-1 is for radiator,I probably need a new wireing harness from the 4 prong plug to the motors, dont know were else to look.

BNaylor
03-01-2008, 08:50 PM
I am thinking now its the diode thats faulty, what are these diodes for on each fan motor for anyway, fan no-2 is for AC and no-1 is for radiator,I probably need a new wireing harness from the 4 prong plug to the motors, dont know were else to look.

Using a diode is common in DC motor circuits not just in automotive use. Generally these type diodes are called flywheel diodes. It is supposed to short out the reverse voltage kick commonly seen in inductive motor loads. You should be able to test the diode with a DMM.

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