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s5 FC with aftermarket Efan won’t turn on and engine is overheating . Have changed thermostat , fan works when connected directly to 12V. Bought replacement 5 pin relay but still won’t turn on. Get 12.5 volts to pin 87 with ignition off, all other pins 0 volts . Pic below is volt readings with ignition ON. 12.2 volts to pins 87 85, 11.8 volts to pins 30 86 ????. Thermoswitch was installed into water pump back and can see two wires under alternator going to relay wire loom
with out seeing the full set up of wiring for the fan it is hard to tell what is wrong. i would check the wires to the thermo switch first. one should be grounded. and the other will go the relay trigger should be # 85. take the trigger wire from the thermo switch to the relay and ground it with the key on or engine running. fan should turn on. if it does it is the thermo switch or it is not grounded good. if the fan does not turn on it is the power supply wire from the relay to the fan
So I cut the two thin grey wires coming from the thermoswitch and twisted the two wires together on the right in the picture. These go to the relay. Ignition on , Fan did not turn on
I made a connection ( white wire) from the fan orange wire directly to the pin in the relay that gave 12.2 volts with ignition on and ground the fan black wire directly to the battery. Fan turned on with ignition . Can I tape up this setup to temporarily run the car or is it an electrical hazard ie (spark , fire etc. ). Also fan did not turn on with existing ground wire going into the relay. When I opened the insulation on the fan black wire and made a connection directly to battery -ve fan turned on
Got fan running with existing relay base hot wire to fan by running a separate ground from fan directly to battery and using a new relay plug and leaving the thermoswitch wires cut and grounded. Fan now turns on with ignition and I can at least drive it until it goes back into storage for the winter . Issue appears to be the ground in the relay . With this setup those two wierd 11.8 volt readings in the base ( pins at 9 and 12 o'clock) with ignition on changed to 0 volts.
09-07-23, 02:14 PM
