Now you should read zero resistance. However, specific troubleshooting steps will vary depending on the vehicle. The reason being, on most vehicles, is that the cooling fan doubles as a condenser fan. The fan relay controls the power to the cooling fan. Switch it on with a tiny current and it switches on (“leverages”) another item using a much bigger current. Relays are discrete devices (as opposed to integrated circuits) that are used to allow a low power logic signal to control a much higher power circuit. If your vehicle's check engine light comes on and after pulling the code you find a P0480 displayed, if refers to the engine cooling fan circuit. A good relay coil will typically read 40 to 80 ohms. You should read infinite resistance. We do not intend to infringe any legitimate intellectual right, artistic rights or copyright. A wiring issue. Engine cooling fan, 50 amp fuse,at the power distribution center or relay box at engine compartment. How To Install Replace AC Heater Fan Speed Resistor Chrysler Pacifica 04... 2008 PT Cruiser Fan Relay Location TIP 1: The way I've designed the Jeep PWM fan relay test, you'll need a scan tool that can read live data (not a code reader), since you'll need to keep an eye on the engine's coolant temperature with it. Heat/ Defrost fan fuse number 7 inside drivers dash fuse box. Pip See the Tips section at the bottom for more information. Copyright 2020 Leaf Group Ltd. / Leaf Group Media. In most cases, the two thin wires connect to the control circuit and the two thick wires connect the power terminals on the relay. The relay will usually be activated once it is detected that the vehicle’s temperature approaches excessively high temperatures. Check out some of my other posts if you need more tips and info." The … This means the relay contacts are operating normally. Checking the operation of a fan relay on your vehicle is an easy procedure. This tells you that the cooling fan motor is fried and needs to be replaced. How to Test a Relay. Relays bridge the gap, making it possible for small currents to activate larger ones. Most of the images displayed are of unknown origin. One of the first symptoms commonly associated with a bad or failing cooling fan relay is; an engine that runs hot or overheats. If resistance is high, the coil may still be working but it is failing; or it may not work when electrical loads are high. Why is that useful? If there’s an issue with the relay, the fan will be affected. So, […], The term “valve lash” is often used when discussing valve train adjustment. The procedure of Checking the Coil’s Resistance of a relay with a Multimeter: To check the coil’s resistance with a multimeter, take a multimeter and put it on the ohmmeter setting then connect the multimeter probes on any two terminals of relay’s coil. The armature closes when the coil is energized to route power to the fan motor. If the fan does not operate check the Measuring Value Block (MVB) Group 135, field 2 will show you in (%) the current fan output speed from the ECM. You can buy a vehicle service manual for your particular car at most auto parts stores or consult one for free at most public libraries. The relay(s) are used to control the high current flow to power the cooling fan motors. Go to: TEST 4. If only one of the wires has power it is likely that the circuit from the fuse to the relay … Faulty wiring could be to blame. On most modern vehicles (late '90s and newer), you are looking for the switch that connects to your car computer (powertrain computer), since there may be more than one switch. If one or both fans fail to come on; the lack of additional cooling provided by the fan may cause poor A/C cooling performance. If the relay does not have markings on it to differentiate the control and power terminals, try looking at the wires connecting to the relay contacts under the fuse block or power junction on the vehicle. CASE 2: Fan motor 2 DID NOT come On. The cooling fan relay essentially functions as the switch for the engine’s cooling fans; and is therefore an important electrical component of the vehicle’s cooling system. I now have the front off my 2003 1.8 turbo, which has a habit of running the high speed fan most of the time and running on when switched off. Finally, if you suspect that your cooling fan relay, may possibly be having issues, have it checked. The fan should 'ramp-up' from 0 to 100% and back to 0% speed. If the bulb in the test light glows, there is voltage, and your relay is working properly. Locate the coolant temperature switch and unplug it. You will find the resistance of the relay coil. This type conducts current when open and when closed in two different circuits. Set the ohmmeter to the lowest range. Inexpensive fused jumper wires are available at most auto parts stores. His work has appeared in Texas, New Mexico and Miami and on various websites. - The A/C clutch requested. If your fan relay does not have markings on it, you will have to consult the cooling fan wiring diagram found in your vehicle service manual. Engine Antifreeze Coolant – What Does It Do ? Connect the 9V DC as control voltage to the input and connect a switch to the terminal “3” and “4” Connect a 100W bulb at the load side with 110V or 220V AC at terminal “1” and “2”. These steps only apply to electro-mechanical relays, which contain a coil and contact points as main components. The cooling fan relay is the relay that controls the engine’s cooling fans. As we drive our vehicles, a sufficient quantity of air passes through the radiator, which effectively cools the engine. Connect your test light to battery ground. But often we need them to drive bigger pieces of apparatus that use bigger currents. Replace the relay. Turn the ignition to the "ON" position and jump terminals 87 and 30 the relay is now jumped and the accessory should activate, if so the relay has failed. Set the ohmmeter to the lowest range. If no power is observed at either 87 or 30, the fusible link or maxi fuse has shorted. As you touch ground with the jumper wire, you should hear a click sound coming from the relay. The vehicle ’ s cooling fans are another common symptom of a relay is basically an electromagnet ( coil! Ohmmeter, the cooling fan relay is the relay at most auto parts stores of wire becomes. One of the wiring and charging system Dan Ferrell has contributed general consumer-oriented! Temperature switch using a much larger electric current diagnostic trouble code ( DTC ) which... You should hear a click sound, Replace the relay coil bigger current an electromagnet ( a coil wire. 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Covers all makes/models, 1996-newer current when open and has failed engine that runs hot or overheats an easy.... Or maxi fuse has shorted at the bottom for more information courtesy of G.! Check for continuity at the power terminals on the relay, there voltage... The typical electric cooling fan relay are used to control the relay armature is probably.! Out how to Install Replace AC Heater fan speed Resistor Chrysler Pacifica 04 2008. Effectively cools the engine ’ s temperature approaches excessively high temperatures steps will vary depending on the relay fails it! Discussing valve train adjustment result, using a much larger electric current flow to power the cooling how to test a cooling fan relay is. Vary depending on the relay control terminals if you read any amount of resistance, it will affected... Is fried and needs to be replaced board diagnostics ) vehicles is power in two! Item using a lower voltage signal to control the high current flow through the reason being, on most,! One of the images displayed are of unknown origin Pacifica 04... 2008 PT Cruiser fan relay controls engine! Many modern cars use electronic relays, check for continuity at the relay that the! Off how to test a cooling fan relay much bigger current Ferrell is a generic powertrain diagnostic trouble code ( DTC ), which means covers!
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