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SVT Shelby GT500
Radiator fan troubles and the fix
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<blockquote data-quote="SCGallo2" data-source="post: 14889784" data-attributes="member: 160791"><p>Cooling fan problems… round two:</p><p></p><p>My low and high speed radiator fan modes had been working well since my last post above. In the spring, I installed a 180 degree thermostat and adjusted the fan trigger temps to 196*F for low and 202*F for high with my handheld tuner, since my new thermostat now regulated engine coolant temp at 186*F at cruising speed. Two weeks ago, after my car sat in the garage for a few weeks, I took it out for a drive and noticed that my low speed cooling fan was not activating, high speed was coming on at 202*F as programmed. I scanned for DTC codes and there were none. I replaced the low speed fan circuit relay and after more testing, found that the low speed fan was working intermittently, still no DTC codes. So I figured the radiator fan resistor was going bad, even though I had replaced the cooling fan and resistor with a 13/14 fan assembly early last year. Ordered a replacement from Tasca for around $30 shipped, installed it, and no change, still intermittent low speed fan. Scanned once again for fault codes and got P0480, low speed fan circuit fail. Went online to HELMINC.com to access PCM troubleshooting procedures and followed the troubleshooting chart which has you check for operating voltages and open and shorted circuits with a multi-meter. I have a career background in aviation maintenance and electronics, so I have no fear of electrical wiring. I ended up isolating a 40 ohm resistance load (should be less than 5 ohms) on the PCM low speed fan relay “command ON” wire: PCM Engine connector pin 7 to low speed cooling fan relay pin 2 (#86 on the relay). I opened up the fuse box in the engine bay and did not find any issues with the wires or connections. So I cleaned the terminals inside the fuse panel and reseated the jack screw connectors on the bottom of the fuse panel. I read the wire for continuity again and this time got 0 ohms, which indicates a good connection. Bottom line: bad electrical connection in the fuse box, and I had done no recent work in this area which would have induced this failure. Took the car for a couple of long test drives in 90 degree heat, and everything worked perfectly.</p><p></p><p>Here are the parts and part numbers for the components I replaced:</p><p></p><p>[ATTACH]44073[/ATTACH]</p><p></p><p>The fuse box can be disassembled by disconnecting the + battery cable wire and loosening the four jackscrews in the center of the fuse box. You DO NOT have to remove the relays or fuses during this procedure; they can remain in place in the upper assembly:</p><p></p><p>[ATTACH]44074[/ATTACH]</p></blockquote><p></p>
[QUOTE="SCGallo2, post: 14889784, member: 160791"] Cooling fan problems… round two: My low and high speed radiator fan modes had been working well since my last post above. In the spring, I installed a 180 degree thermostat and adjusted the fan trigger temps to 196*F for low and 202*F for high with my handheld tuner, since my new thermostat now regulated engine coolant temp at 186*F at cruising speed. Two weeks ago, after my car sat in the garage for a few weeks, I took it out for a drive and noticed that my low speed cooling fan was not activating, high speed was coming on at 202*F as programmed. I scanned for DTC codes and there were none. I replaced the low speed fan circuit relay and after more testing, found that the low speed fan was working intermittently, still no DTC codes. So I figured the radiator fan resistor was going bad, even though I had replaced the cooling fan and resistor with a 13/14 fan assembly early last year. Ordered a replacement from Tasca for around $30 shipped, installed it, and no change, still intermittent low speed fan. Scanned once again for fault codes and got P0480, low speed fan circuit fail. Went online to HELMINC.com to access PCM troubleshooting procedures and followed the troubleshooting chart which has you check for operating voltages and open and shorted circuits with a multi-meter. I have a career background in aviation maintenance and electronics, so I have no fear of electrical wiring. I ended up isolating a 40 ohm resistance load (should be less than 5 ohms) on the PCM low speed fan relay “command ON” wire: PCM Engine connector pin 7 to low speed cooling fan relay pin 2 (#86 on the relay). I opened up the fuse box in the engine bay and did not find any issues with the wires or connections. So I cleaned the terminals inside the fuse panel and reseated the jack screw connectors on the bottom of the fuse panel. I read the wire for continuity again and this time got 0 ohms, which indicates a good connection. Bottom line: bad electrical connection in the fuse box, and I had done no recent work in this area which would have induced this failure. Took the car for a couple of long test drives in 90 degree heat, and everything worked perfectly. Here are the parts and part numbers for the components I replaced: [ATTACH]44073.vB[/ATTACH] The fuse box can be disassembled by disconnecting the + battery cable wire and loosening the four jackscrews in the center of the fuse box. You DO NOT have to remove the relays or fuses during this procedure; they can remain in place in the upper assembly: [ATTACH]44074.vB[/ATTACH] [/QUOTE]
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Radiator fan troubles and the fix
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