Blown fuse leading to radiator fan. Please help.
December 11, 2010 9:29 AM Subscribe
My radiator fan won't kick on when the car gets hot. I replaced the fusible link and let the car idle for awhile. After 15 minutes or so, the fusible link blew... Need specific advice on how to find the short circuit.
posted by Slothrop to Travel & Transportation (3 answers total)
I had a problem awhile back where my 1995 Ford Escort wagon went completely dead and wouldn't start. It had a likely short circuit. I took it to the dealer and they replaced the ignition switch and the neutral safety switch. I got the car back and moved to another city in another state (Charlotte, NC). Now I drive in a bit more traffic and I noticed that the car would get too close to overheating in really slow traffic. Yesterday, I had some time to work on it and I flushed the radiator with a product from Prestone. I flushed it three times and got lots of gunk out. I was quite happy and left the car to idle for awhile to mix the coolant and water as suggested. After twenty minutes, I check on the car and the temperature gauge was dangerously close to hot again (pretty much 4/5s of the way to the end of the gauge).
This morning I looked in the engine fuse box and the fusible link for the fan was clearly fried. I got a new one at Autozone and put it in hoping to solve the problem. When the temperature gauge started creeping up I opened the fuse box in time to watch the fuse glow bright red and then "Pop!"
I have a multimeter so I could try to check for a short circuit. I have been reading all morning on how best to do this, but I am intimidated as I have generally only worked on mechanical bits with cars. I really want to learn how to fix this (the dealer charged me $1000 for the work they did, which really, really smarted), but I am also cautious about electricity.
I have the wiring diagram for the car in a Haynes manual, but I don't have any experience reading the diagram, so I am a bit overwhelmed by that, too. It looks like I would need to check the wires to the starter, to the ignition relay, to the fan itself, to the engine electronic control module, etc.
From what I've read, I need to
1) Disconnect the positive terminal for safety.
2) Cover the positive terminal to prevent accidental contact (any good recommendations for what to do this with?)
3) Trace wires from the fan itself to the ECU to find bad wires.
3a) Unwrap a bit of wire and hook part of my voltmeter up to the wire and another part to the chassis to make a ground. Look for 12v readings. Should I use a particular lead on the wire versus the ground?
3b) Do I start with the fan or trace backwards from the fuse box to the ECU? Does the blown fuse indicate a particular direction to look for shorts?
3c) Do I need to check wiring in other components? The wiring diagram shows that the starter, ignition relay, ECU and fan are all on the circuit...
3d) If the fan is the only electrical thing not working and the only blown fusible link, does that narrow down what I am looking for?
Sorry for such a long question! Thanks in advance for any leads!