Need some help with electrical issue(s) in my focus

MattJ03

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Mount Dora
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FL
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United States
What I Drive
2004 ford focus SE 2.0l
#1
Can anyone give me some advice?
I am unfortunate enough to own an absolute lemon of a 2004 ford focus with the 2.0l zetec motor.
About a month ago, i was driving down the road with the car running fine and suddenly it just died. I came to find out that it blew the 20A maxifuse (F#9) responsible for the "engine management system". It won't crank at all without that fuse, so after towing the car home with a strap and looking around for any issues i found that the connection for the fan relay resistor was completely chunked. Melted and corroded. Took it out, replaced the fuse, and the car ran fine again so I didn't think anything of it. This was ~3-4 weeks ago. This past sunday night, I was driving down the road again with the car running normally, and the same thing happened. Popped the hood, and I see that the same fuse is blown again. Tried replacing the fuse again twice, and it blew them both as soon as I turned the key to acc. I spent HOURS looking for any exposed/bad wires, shorts, grounds, anything, and the only lead I have is the fan relay resistor. I managed to repair that relay temporarily today by scraping off the melted plastic and corrosion, JB welding the connector back together, and zip tying the wire to the resistor so it wouldn't come off, just until the new ones come in. Did that, replaced the fuse, and once again the car ran fine. Took a drive up to my local ford dealership to get a refund for the resistor I had ordered from them, because i found the resistor and the connector online together for the same price. Backing out of the dealership's parking lot, the car died again as soon as i put it in reverse. Restarted the car, and it ran fine again. I chalked it up to my battery being a little low since it was dead, and i kept driving because i had to stop at the gas station. Because i figured my battery was low on power, I left the car running. Upon attempting to back up and leave the gas station, once again the car died as soon as i put it in reverse. After that, the car wouldn't even crank and i had nothing but my gauge cluster lit up like a christmas tree. Tried jumping it, no crank. Checked every fuse, all fine. Checked the fan relay resistor, still connected. Checked every relevant resistor, and still nothing but some clicking coming from the fuse box. Had to have a friend come pick me up after 2 hours at the gas station spent on the phone with my insurance company/waiting for a tow truck. Any clues what could be causing all these issues?
 

Handy Andy

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#2
The Resistor to drop the speed of that fan, is ABOVE the fan, in the typical circuit - this means...

The Relay sends power THRU the Resistor FIRST, then it goes thru the FAN.

The opposite should have been done - by Ford, but you can "jumper" the resistor - and install the Resistor on the opposite GROUND leg of the Fan - or just do away with it completely. That fan will be noisy, but it will do the job it's there for.

The Opposite would be - place the FAN on the hot side to the battery and relay - with the Relay being "grounded" on it opposite leg.

This way, the fan is powered but the circuit is completed only when the relay is on, grounding the circuit to complete it.

Then the Relay for the low-speed side - the one that uses the resistor - this would not happen because the resistor is on the grounding side of the circuit - so if a catastrophe were to occur to the resistor assembly - the fan DROPS current thru itself first then the resistor - so the FAN would run (High speed or not at all) but the fuse powering it wouldn't be sacrificing itself all those times and the Fan would still run in High speed when that function is needed. (Fuse didn't blow)

But - the problem with the resistor - it is used to drop current so the fan runs slower during the times that the Fan NEEDS TO run - this saves the relays the fan and the power from the battery supply (charging system e&c) - so to do away with it is not recommended but if you can put the resistor on the Fans ground leg, and run a Relay to BYPASS the resistor (act as a short) when needed - then the Fan will run high speed as needed - low-speed all else.

That works for Hot climates, cold winter not so much.
 


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