Dealers have it now as a one piece unit . Cut and strip wiring close to the resistor . The wiring on the new part is already stripped . Just get a coupla` butt connectors , stick the wire in and crimp it , and repeat 3 more times and you`re done ! Easy peasy ! peace

 

Do you have a part number for that? That sounds easy enough...

 

No , just walked into Ford dealer parts department , told `em what was needed and they got it for me . So glad they did away with the male/female plug and just went with wires . One less thing to go bad .
peace

 

About freakin' time too, the small size of the spades there is what causes the trouble to begin with. Those two are smaller than anywhere else in the system. Part designer/engineer asleep that day.

And yes, the norm is to change both sides of the connector, the harness side spades will have opened up from heat warpage and simply using that connector will melt the new resistor lickety split from bad connection again overheating.

Ahead of them. I rebuilt mine using the same resistor and no connector as well, bulletproof. Been working fine for a long time now.

 

Do butt connectors work well enough to connect the wires or is soldering a must?

 

Soldering and heat shrink would be ideal but if you don't want to go that route try to find the butt connectors with heat-shrink. I would highly recommend them for this application since they will be under the hood and would be subject to moisture. I used the butt connectors with heat-shrink for this same issue on my last focus and never had any problems with them.

 

Connectors have worked fine for me...just over a year now
peace

 

I used them too, working fine. The degree of squeeze you put there has much to do with it. I squeeze mine using vise grips and not a pretty looking connection but rock solid voltage there. If you wimp out to make the connection look pretty, well, you're on your own there. What do you want? Fixed right or pretty?

Soldering would be swell if you are so inclined...............

 

The fans were not running on low speed as they should, so they were going from a dead stop to high speed. This put so much load on the electrical system that it caused the engine to stumble. I had not experienced engine overheating.

My connector was burned up, but the resistor assembly was okay except for corroded terminals due to the heat.

My solution was to (1) cut the casing off of the resistor assembly, (2) drill holes in the spade terminals, (3) wire brush the terminals to clean them, (4) cut off the burned connector, (5) solder on ring connectors, and then finally (6) bolt the ring connectors onto the terminals.

The fans are working correctly now. I'll pull the assembly back off and cover the exposed electrical terminals with JB Weld this fall if it seems this will be a permanent fix.

 

you did a thorough job; keep us posted as to whether it remains reliable long-term.

A possible failure point is the terminals. I suspect that these connectors burn up not due to high resistor temperatures, but rather due to localized heating on the terminals themselves: the rubber seals fail and then the terminals corrode, which increases the resistance (and thus the heat). Grinding the corrosion off the terminals leaves too little copper; again, increasing the resistance (and thus the heat). Drilling holes in them further reduces their volume, further increasing resistance (and thus the heat). It all adds up to less copper, more resistance, and more heat - which brings things back to square one: melted junctions.

 

Thank you for the info. I'll post back on how well this works out.
I found this problem while trying to figure out why my engine stumbled / stuttered when the fans turned on. The stumble was very noticeable when stopped and in drive. I was surprised to find it because I hadn't had any cooling problems. This was a quick fix for me since I had all the items on hand. My engine no longer stumbles with the fans coming on now, but I am still hunting another electrical problem (that's another story).
BTW, I used #6 stainless steel screws, lock washers, and nuts if anyone is curious.

 

The spade size used there is smaller than elsewhere in the fan wiring. It is the cross section from male spade to female that is too small in area, the spades then overheat even with a perfect weather seal. Resistor coil gets really hot too, why it is mounted in fan air flow there. The resistor then radiates heat down through the spades to add to the problem.

 

Thank you amc49. It could be as my_beautious_ZX3 pointed out that the problem starts with the connectors, but I am more with you in believing that the failure process is influenced with the heat from the resistor. It is a chicken and egg thing anyway because once the connector begins to lose its conductivity then it becomes a source of heat that expedites the corrosion / oxidation and eventual total failure. I am going to keep an eye on this and, if it does not exhibit any signs of failing, I will coat the connections with JB Weld to seal everything up.
BTW, the terminals are tin plated brass. I’m sure my_beautious_ZX meant to say brass instead of copper.

 

The resistor's native heat is not a significant instigator in these melted harnesses or else the melting connector problem would arise during the new vehicle's first summer, rather than after it reaches its half-decade birthday. I give the Ford engineers enough credit to have bench-tested this design prior to signing-off on it; a junior in high school could figure out how to run nominal amperage through a resistor and measure the radiated heat.

I’m sure my_beautious_ZX meant to say brass instead of copper.

nah he didn't. Mine was so corroded that it could have been made of sticks & mud and I wouldn't have been able to tell the difference.

And, welcome to the forum.

 

Thank you for the "welcome" and your sense of humor.

If this repair works or it fails, either way I will post back. If it fails, I see that I can buy a repair kit (pigtail, resistor assembly, and connectors) on Amazon (Dorman 902-219) for $25.78 with free shipping. For right now though, I consider this an experiment as I have never seen one of these repaired this way.

 

Don't coat any connections in JB weld, it has metal powder in it and conducts electricity. If anything, use a dead clear epoxy. Any coloring may conduct. I've used clear epoxy to seal distributor caps when I used to carry spark plug wires out of the sides of ones with top posts. Needed for a custom intake manifold at the time. It worked fine, but I sure got lots of questions on the cap.

 

Thank you for that info! It was a concern that I was going to check into before using it because I have had strange things happen with epoxies before. On one occasion I had coated a thermistor with a clear two-part epoxy that measured infinite resistance at room temperature. I thought it would be perfect for the job, but then I couldn't get the circuit I was building to properly function at higher temperatures (about 175 degrees). I finally found that the epoxy was becoming conductive at elevated temps and of course was affecting the resistance of the thermistor. Further testing revealed that the epoxy became VERY conductive at temps above 200 degrees. Lesson learned!

I am leaving the terminals uncoated for now as a way to monitor the repair under worst-case conditions. Being able to observe the connections while they are exposed to the harsh environment under the hood should tell me a lot about how this method of repair will perform over time.

Again, I know I can replace everything for about $30. I did this repair as a quick fix just to get my fans working properly again, but now it has peaked my curiosity...could this actually work better than the original connector? Hmmmm…

 

Yes it could easily. I covered mine with silicone after done. The snap connectors were changed for positive screw together screws, like 4-40 or close. Used 10 gauge wire. Nothing there except a coil of wire, it by itself cannot go bad. Part snapped back in place like factory. Working fine.

Thermistor may have been affected by no air around it, if it was intended to be in open air radiation that could affect your work too. I had no trouble using the epoxy (Borden) in underhood temps and spark voltage from electronic ignition and a Accel Supercoil. Closest jump point was about 1/8" from ignition wire to aluminum intake. Never jumped there at all. Could be the brand? You never know what's in that stuff...........

 

Sounds like you made a good repair. Do you have a photo posted in another thread perhaps? Again, I am just the curious type. As they say, there is more than one way to skin a cat!

As for the thermistor and epoxy experience I encountered, the design requirements we had from Mazda required that the thermistor be enclosed in a protective case. I had grabbed some epoxy we had in our lab while I was building the prototype…it was not the epoxy we normally used in production. I never used THAT epoxy again! So yes, the strange characteristics were brand specific.

Silicone is great for waterproofing electrical connections as long as it is not one of the room temperature vulcanizing (RTV) types. They release acetic acid and that’s very bad for electronics.

 

Maybe not the later stuff which is low volatility, the smell of vinegar is pretty much gone. Seem to have no trouble sealing up normal 12 volt stuff with it. Maybe sensitive low volt electronics yeah. Although I have 2-3 places now in sensor pigtails where I have patched in small crimp connectors at $.25 each to not buy a $20 pigtail. I drill out the pigtail outer plastic housing for room to install the crimp then flood the inside with silicone to waterproof it. No trouble yet and they have been on there a couple years. It'll be fun peeling that connector apart but who cares. I loathe $20 pigtails, they should be maybe $3-$4. Just like the $4 bulbs you get at parts store that only costs them forty cents a pack. Screw city there.

 

You're right. I guess to clarify myself, I should say that there are RTV silicone formulations out there that are okay to use with electrical circuitry. The really bad ones have the strong vinegar smell. If that odor is missing or very light, it might be okay to use. I just prefer to stay away from RTV altogether rather than to try and figure out which ones will do harm and which ones will not.

 

The strong smell ones will waste O2 sensors pretty quick too. Why the stuff was reformulated.

 

I believe the O2 sensor issue for sure!

I had a really bad experience with RTV and electronics many years ago. I have stayed away from it since that happened.

I have used some other silicone sealants that release methanol and ammonia during the cure process. So far I haven't noticed any problems with them.

 

Since the discussion of what causes the connector to the Focus radiator fan resistor assembly to fail was brought up, I thought I would do an autopsy on my connector.

Photo 1 shows the wiring connector. Notice that the right-hand terminal has sustained more damage than the left. This is comparable with the majority of other photos I have located on the Internet. The resistor connects directly to the right-hand terminal and the thermal fuse connects to the left-hand terminal. That’s the first clue that resistor temperature is playing a role in the failure. More heat would reach the right-hand terminal than the left because the thermal fuse provides some heat buffering. (The item on the right in this photo is the part I cut off the resistor assembly.)

Photo 2 shows the connector cut open. There appears to be no signs of corrosion due to water entry either through the back (around the wires) or front of the connector. Oxidation is apparent on the part that contacts the male terminal. This is consistent with operation at high temperature.

Photo 3 shows the two female spade terminals. Notice that the terminal has four tangs to provide pressure to the part that mates with the male terminal. Also note that the connector is not closed as if the pressure tangs have lost their spring. This may be due to overheating or maybe it was made that way.

Photo 4 shows a washer of similar thickness to the male spade terminal inserted into the female terminal. Contact between the washer and the terminal is only made at the tips right where the pressure tangs are located…a very small area.

Photo 5 shows how I made a repair by drilling a hole in the male terminals and attaching ring terminal connectors as I described in my earlier posting.

I measured 4.55 volts across the resistor with the fans running. The resistor measured about 1 ohm. That means about 21 watts of heat is being generated. Most of that heat dissipates into the air, but apparently a lot must be traveling down through the resistor assembly terminals to the wiring harness connector.

The challenge for any electrical connector under the hood is making and maintaining the required mechanical and electrical connection over a wide temperature and humidity range. A good low resistance connection is mainly dependent on the (1) surface contact area between the mating parts combined with (2) sufficient pressure. This connector appears to be lacking those two key ingredients. In my opinion, this connector is not well suited for this job and is failing due to heat from the resistor. Perhaps in newer models Ford has changed the connector type. Let’s hope!

 

Good write up and explanation!!! Can`t wait now till one of the newer units go bad....the ones with no male/female connections showing , just a pigtail only .
I wanna` see what Ford has done on them to try to solve the problem .

 

That #5 pic should work well like that, mine implemented a bit messier since it melted more but same thing done there. I bypassed and removed the thermal since it doesn't appear to work anyway. Just keep an eye on it, but should be bulletproof. And much cheaper than new part which will melt again.

Excellent, I'm sure others will appreciate the #5 pic to easily illustrate the idea.

They are getting to where they don't care so much about the reliability of the parts, more is being put into allowing parts to go together by hand with no tools used at all and quick. Lots of electrical troubles beginning to show in ALL cars now because of that mindset. Many more fires in cars now than used to be..........

 

I agree that reliability seems to be taking a backseat nowadays. This problem started on my car when I had only about 70,000 miles on it. If I had 170,000 then I would expect things like this to be going on.

I'd like to see one of those new "pigtail only" units. Ford must have realized that they had a design flaw and totally took the connector out of the equation.