cooling fans are not coming on.
fuses good, fans work when a jumper is used, switched relays around, power to the "fan 1" relay. fans come on when a jumper is placed from position 1 to position 4
Hello, thank you for choosing Just Answer. My name is XXXXX XXXXX X will help with your cooling fans not coming on. It sounds like you have done some good testing so far. We know the fans are good, the relay is good, and the wiring from the relay to the fans is good as well. The only other likely culprits are your ECM or coolant temp sensor.On your Altima, the temp sensor is the same part as the temperature gauge sending unit. The ECM reads inputs from the speed sensor, temp sensor, camshaft sensor, and A/C controls. From there it sends the signal for to the relay to turn on the fan(s). The fan switch/temp sender unit is less than $20. It is worth a try replacing it. However, if that does not solve the problem, your ECM is likely the failed part.I hope my answer is helpful. Let me know if you have any additional questions.Best Regards,Stephen
just replaced temp sensor, sending unit is separate unit. also have a few other issues, would ecm cause the digital clock to go off when i step on brakes?? Did eng swap in the car, previous owner blew motor, believe because the fans quit on him, said it overheated on him and then it quit. where is ecm, would ecm from 97 with same options interchange?
Clock going off when you step on the brakes sounds like a bad ground (somewhere). The ECM is located under the dash, in the center of the car, below the A/C controls. You can access it from the passenger side or driver side.The '97 ECM won't work. In 1996 the engine controls went from OBD1 to OBD2. You would need a '93-'95 with the same part number on the case.
any way to test ecm? other things that would also point to that as issue? will be hard part to aquire just for a "hunch"
You can try to trace wires back from the signal to the solenoid to the ECM harness, you can do this with a multimeter. But, that will only tell you if the wiring is good between the ECM and relay (99% chance it is fine). You could test the ECM by checking for a signal to the fan relay when the engine is warm enough to turn on the fan, or with the A/C on. There are a dozen or more ECMs for your car on E-bay ranging from $40 to $150. I'm sure one of them matches the numbers on yours. Make no mistake, this is more than a hunch. Every other possibility has been ruled out. Were it my car, based on what you have told me, I would replace the ECM.
oh, forgot, if it helps in diagnosing, the fans also do not come on with the A/C, would that narrow it down a little? i am not sure about temp that the fans come on, gauge has never left the middle point on dash but does not read degrees. I have an infrared temp sensor and have been checking it but cant find a resource that tells the temp they are suppose to come on.
Again, turning the A/C on sends a signal to the ECM which sends the signal to turn on the fans. So that lends additional credence to the theory. The fan should come on between 2/3 and 3/4 of a gauge (possibly less). If left to idle the engine temp will eventually climb enough to make the gauge move. The fans should come on between 200 and 220 degrees F (the actual temp will vary with the sensor's sensitivity).
5+ years managing an auto repair shop. Many, many Nissans passed through.