Check the electrical connection at the fan. If you’re tracking down a wiring issue, Eautorepair.net is the better choice. If you have a P1491 Radiator Fan Control Relay Circuit trouble code, this post will help you understand what it is and how to fix it. A/C refrigerant pressure sensor 10. - The vehicle speed is less than 38 MPH. If there was no switched power at the relay, the ignition switch is suspect. Until such time as you can either complete your checks of the circuits or take the car to a service facility, pull the fuse in the fuse relay … Most cooling fans use electric motors that have a moderate to high current draw, and as a result are commonly controlled using relays. This tutorial will help you to diagnose the Pulse Width Modulated (PWM) fan relay on the 1999-2003 Jeep 4.0L Grand Cherokee SUVs and/or the codes P1491 (Radiator Fan Control Relay Circuit).The dealer, at the time of this writing, will charge you $95 (US) to diagnose it. The cooling fan relay is the relay that controls the engine’s cooling fans. Alldatadiy.com, on the other hand, uses the factory diagrams. Look at the markings on top or side of the relay case and locate the two control circuit terminals, which connect to the relay's coil, and the two power circuit terminals, which let electrical current pass to the fan. Check the terminals for an additional power terminal and look where it would be on the relay. Verify the battery positive terminal in the relay block with constant power. Poor electrical connections in the cooling fan circuit 6. Disconnecting the PCM could cause loss of programming and the vehicle may not start unless towed to the dealer for reprogramming. IAT (intake air temperature) failure 8. When coolant temperature rises above acceptable limits, the computer provides ground to the fan relay. Faulty cooling fan 1 3. Additionally, many vehicles have multi-speed fans requiring as many as three fan speed relays for low, medium and high. What does that mean? The bottom of the fuse block lid will usually indicate placement, but if not, look in the owner's manual. Defective faulty fan control relay 1 2. When the PCM attempts to activate the fan and senses the command and the result do not match, the code is set. Faulty VSS (vehicle speed sensor) There are multiple factors that can lead to this error code. Most late model vehicles use an electric fan to pull air through the radiator. A relay kit, our part number CCFKRL, will include everything you need to properly wire up your electric cooling fans, with the exception of additional wiring needed to complete all of the circuits. Shut the engine down and pull the CTS plug again. If the fan operated, check the relays. If the circuit has not closed or the relay has not clicked, the relay is bad. - The vehicle speed is less than 38 MPH. ground switched device using a simple spst relay. + + this will be your new ground switched output. Dodge Radiator Fan Wiring Diagram. Look at the side of the relay for the switched power terminal or just turn the key on. See the schematic printed on the relay itself or consult the schematic in your vehicle repair manual, if necessary. you take on any vehicle. If they prove to be good, check the CTS with an ohmmeter. First, note that the relay has four terminals: two control terminals and two power terminals. The fan relays are nothing but a remote light switch. The cooling fan relay coil receives the Ignition Voltage directly. The PCM (powertrain control module) senses the increase in engine temperature through the CTS (coolant temperature sensor) located near the thermostat. When the temperature reaches about 223-degrees F (value depends on make/model/engine), the PCM will command the cooling fan relay to turn on the fan. This is a generic powertrain diagnostic trouble code (DTC) applicable to most 1996-newer vehicles. Set the … If the above procedure could not find a failure, the probability is that a poor connection to the PCM or the PCM itself is at fault. Let the engine cool and put the ohmmeter on the 200,000 scale. Spin the fan with your finger (make sure the vehicle and key is off). Mount the fan as high up on the core as possible. In most cases, their diagrams are right from the factory manuals. Pull the connector off. Recently, I was driving my 2015 Jeep Wrangler JK Unlimited through a parking lot on a 95 degree day, and after leaving a stop sign, a check engine light flashed on (later I would learn it was a P0480 Cooling Fan Relay 1 Control Circuit), and shortly thereafter my Jeep overheated. So you have to refer to the factory legends to learn the identification symbols and then refer back to circuit diagrams to find the splice and ground locations. C5 corvette electric fan relay wiring to wire an electric fan with a relay arduino controls fan tutorial trinary switch infinitybox 12v toggle switch wiring… Best Fan In Thestylishnomad.Com 13560+ Best Fan Thestylishnomad.Com 2019 That saves a lot of time because you don’t have to refer back to the component locator or circuit locations. Get the BEST auto repair information Alldatadiy.com and Eautorepair.net are professional-grade shop manuals—period. A constant power supply from the battery is present on a terminal in each of the relays. It is a generic code applying to all OBD II (on board diagnostics) vehicles. When … By using a lower voltage signal to control the relay, there is less stress on the rest of the wiring and charging system. Check all the relays in the same fashion to be sure they are all working. The operating components in the cooling fan circuit include the cooling fan fuse, relay, coolant temperature sensor and the computer. Anyone know where the relay for the cooling fan is? The cooling fan relay takes the low voltage signal and internally switches the relay “on” to allow battery voltage to be supplied to the radiator cooling fan. The opposite side goes to the fan. Use a test light to find the hot terminal. Poor electrical connections in the cooling fan circuit 6. 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. Defective or faulty fan control relay 3 4. your question in our FREE car repair forums. This will allow mounting of the fan(s) without compromising the core of the radiator. Faulty VSS (vehicle speed sensor) Repair if necessary and use dielectric grease on the terminals. The schematic will help you also when checking the fan cooling circuit. The reading will be about 2.5. Use an ohmmeter to test that the constant battery terminal and the fan harness terminal have continuity meaning the circuit has closed. P1491 Radiator Fan Control Relay Circuit P1491 Radiator Fan Control Relay Circuit. - The A/C clutch requested. A switched terminal will be hot only when the key is on. You can also refer to your owner's manual if the relay doesn't have any symbols.Resistance Test: 1. The ground completes the circuit to the relay and switches power to the fan. The cooling fan relay is an electromagnetic switch that controls the power supply to the engine’s cooling fans. A malfunctioning cooling fan relay can … If they are good pull the cooling fan relays out. A/C selector switch 9. The radiator fan switch relay may not be supplying power to the fan. There is a problem within this circuit causing the fan to fail to operate allowing the engine to overheat while sitting still or driving at a slow speed. It is always a wise idea to look up the technical service bulletins (TSB) on your particular vehicle to see what type complaints have been coming in to the dealer service department related to this code. It does so by supplying the ground to the relay. (Please call for fan shroud suggestions). Electric fan is responsible for causing air movement around the engine coolant radiator. You just want to know if it's working. Most late model vehicles use an electric fan to pull air through the radiator. If swapping relays still doesn't operate your cooling fan, make sure the relay is receiving power from the computer. Electric Fan Relay Wiring Diagram– wiring diagram is a simplified tolerable pictorial representation of an electrical circuit.It shows the components of the circuit as simplified shapes, and the capability and signal contacts between the devices. Refer to the top or side of the relay to locate these terminals. The amount of air movement caused by the fan is controlled based on the Vehicle Speed, coolant temperature, A/C pressure status, A/C switch request status, and A/C clutch state. Open or shorted fan cooling fan harness 5. cooling fan relay wiring diagram – You will need a comprehensive, expert, and easy to understand Wiring Diagram. With this sort of an illustrative manual, you’ll have the ability to troubleshoot, avoid, and complete your assignments without difficulty. Pull the connector apart and look for corrosion or bent pins. Video on how to diagnose dtc p1491, radiator fan control relay circuit malfunction on a 2003 jeep liberty sport. 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. - The vehicle speed is less than 38 MPH. The vehicle's PCM's function is to act as a ground to operate components, not to supply power. 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