Where do I pinpoint test the relay trigger voltage for the cooling fan relays?
2000 Crown Vic Police Interceptor. I'm not a Ford electronics guru so please excuse my terminology if it's wrong. My radiator cooling fans quit working! I jumped the cooling fan high-current voltage wires for both the low and high speed relays to verify that the fan operates on 'low' and 'high'. This was done at the relay sockets, to verify that I have high-current voltage at the relays and that the fan works on both speeds. OK good. Both of the relays are getting the ground trigger from the PCM (verified with multimeter and scan tool - when scan tool says low fan is on, I get ground at the relay ... when scan tool says fan is off, I get open ground). PROBLEM: neither relay is getting the low-current voltage to the coils to complete the circuit. From what I can tell by the schematic, the coils of both relays get their voltage from the same source point, which is why neither of them work. Can you tell me where to start tracing backward to find the open circuit? What I need are the actual physical locations to probe. For example, if you say, "check for voltage at the XYZ relay and also at test point 123" ... please tell me the physical location of XYZ relay and where test point 123 is found in the engine compartment. The voltage wires to the relay coils are solid red and disappear into miles of split-loom tubing :-) Am I on the right track or just totally shade tree certified? Thank you in advance!
Possible bad temp sensor
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