Fixed 03 Explorer 4.6 wiring
So today, I decided to tackle the job on my 03 Explorer 4WD 4.6 as well. Along the way, I decided to document the fix since this is apparently a very common issue.
Here's the damage...
Here's the damage when the harness is unwrapped and wiring exposed...
Here's the harness sticking out the drivers fenderwell...
Here's a step by step on how to fix it.
1) Disconnect battery - 8mm wrench
2) Pull one clip out of the flexible fender liner material in the RF wheel well, to expose the side of the AC compressor.
3) Unplug AC Compressor clutch harness connector.
To do this, squeeze the tab on the clip and pull the connector off. This was the hardest part of the job, due to the awkward location of the connector. I was on my back, with one hand thru the fender liner and the other hand up the front of the motor. My legs were under the truck facing rearward, and my right elbow was just above the power steering cooler. Watch the cooler, it's sharp.
4) Unplug the oil pressure sending unit harness connector. Squeeze the tab on that clip to remove also.
5) Remove LF wheel and support the truck with a jack stand.
6) Remove both starter wiring nuts, 13mm and 10mm sockets, 1/4" ratchet.
7) Unbend the harness holder that's right behind the AC compressor, to get the harness out of it. You'll need some sort of tool, because it's pretty strong. I used a door panel clip removal tool. It's basically a screwdriver body with a V shaped chrome end on it.
8) Unbend the harness holder near the oil filter. I found it easier to both unbend it and unbolt it from the front of the motor, two 10mm nuts.
9) Remove the harness holder from the harness and set aside.
10) Pull the harness up thru the left inner fender liner. Note the routing of the harness first!
11) Remove the harness wrap about 6" in both directions from where the damage is. That should be right about where the oil pressure sensor connector harness branches off.
12) Repair the harness.
In my case, the harness had a hole in it, and oil had worked its way into the harness further than you might think. So I opted to remove all the wiring harness wrap from the entire harness that I could get to, clean everything up with brakleen and paper towels, and rewrap everything with fresh electrical tape. I also rewrapped the ends of the harness with cloth tape, just like the factory did.
I also opted to remove a couple inches of bad wiring, and solder in a short replacement section. I made sure to use soldering flux to clean the original wiring before soldering, as it looked dingy. I also heat shrinked the wiring. Don't forget to slide the heat shrink on before doing the soldering! If you use a butt connector, get the good ones that are waterproof and have heat shrink built in. Crimp, heat up the shrink, and done.
13) Reinstall as removed. Be sure to get the routing right before plugging anything back in.
14) Bend the harness brackets with a pair of duckbill pliers, so that the harness is held in a natural position, not kinked. Keep the harness away from everything. I found that the harness was also vulnerable to sitting right on top of some power steering lines, which could rub a hole in the harness over time. So follow the entire harness with a flashlight and make sure you have a fingers width between the harness and everything else at all times.
15) Remove the oil drain slide (three 13mm bolts), and trim some off. Be sure not to trim too much off. You'll have already gaines some clearance by getting the wiring laid out and the brackets bent to a better shape. But I trimmed also, to make sure. Make sure you don't trim so much that the oil drips off the filter housing and onto the ground instead of the slide.
That's it. The hard parts were removing the harness connector on the AC compressor, cleaning the oil that had worked its way into my harness wrap, and getting the harness to feed in and out of the LF fenderwell. That took a couple back and forth trips from the side of the car to under the car. Two people here would have been nice. Putting the connector back on the AC compressor proved hard as well. Push hard until it clicks.
In my case, there were 2 damages done. The white wire w/ red stripe was completely broke in half, and the positive battery cable was cut into, but not much. Since the cable was still mostly there and good, I opted to get out my big heat shrink tubing, unwrap the entire harness, and heat shrink over the damaged battery cable. If the damage was worse, I would have had to replace the + battery cable.
I also took the time to note the wiring and see what all was in there...
Large red cable - positive battery cable to starter
Yellow/blue wire - Starter solenoid
Gray/white wire - AC Compressor +
Black wire - AC Compressor -
White/red wire - Oil Pressure Sending Unit
So in my truck the oil pressure sending unit wire was cut in half. The positive battery cable was cut into, but not badly damaged. However, the two exposed wires could have touched each other, sending 12v into the oil pressure sending unit wire. Who knows what evil that could cause.
Here's the fixed wiring...
And finally all buttoned up...