A common problem with Rangers and Explorers alike seems to be the antilock brake system, whether it's 4WABS, RABS, or front ABS. My Ranger is equipped with 4WABS, so these guidelines will be based around that. Please do note that these are not definitive numbers and simply a baseline to help you pinpoint your problem.
As always, I, nor fordrangerforums is responsible for the decisions you make. Be safe, check your work, and good luck.
First, you will need some tools.
A laptop
an OBDII to USB cable which can be obtained on ebay for less than 10 dollars in some cases. Mine is the ELM327.
A multi-meter with probes (preferably digital)
and a piece of free software from FORScan.org. It is a windows beta EXE and is completely free.
Before we crack out the software, we'll first check a few things with our multimeter. Take your keys and turn the ignition to the 'run' position without starting the engine. It's safer that way, else you may get burned while under the vehicle.
If your vehicle has front wheel ABS, look behind the bumper for a pair of connectors, round in shape. Each one has two pins, and look like this.
Facing forward with the vehicle, unplug the right-most connector, or leftmost if you're on the passenger side. Set your multimeter to DC volts and measure the voltage coming out of the vehicle's harness. You idealy should see around 2.5 volts. If you do, proceed to the next step.
Take the plug and measure it's resistance, setting the meter to 2000 ohms. The front sensors should measure around 400 to 500 each. My driver's side sensor measures at 490 ohms, and the passenger side reads 420 ohms. If there is an infinite amount of resistance, replace the sensor. You can keep your bearing if you like.
Now, if your Ranger is equipped with rear ABS, crawl to the rear. Follow the driveshaft to the differential. At the top you will see a cable coming off the top.
*Not my picture*
Unplug this and measure the voltage coming off the cable. Again you should see around 2.5 volts. If you do, proceed to measure the current of the sensor. This sensor will measure considerably higher. Mine measures coincidentally at 1911 ohms.
No matter what you're equipped with, make sure all your connections are clean and tight. Use some contact cleaner if the problem doesn't go away.
<sidenote>
There is no way to reset the codes without software. Don't waste time disconnecting your battery. The ABS system conducts a self test every time the ignition is turned on.
</sidenote>
Now if you still have the problem, use your new software, laptop, and obdii cable.
Again, turn your key on to the run position without the engine running and establish the connection to the vehicle.
Now click the clipboard and you should see a variety of tests, including the ABS test. Run the 'on demand' test for the ABS system. You should hear a click or two and the ABS light may flash.
The software will then briefly come back with your results. If no code is found, the light will cease to burn. If there is a code, it will reveal it to you for further inspection.
Your code should begin with the letter C and a few numbers and will tell you what the problem is.
As an example, say your code comes back as C1230. It will tell you that there is a problem with the rear sensor, which could be caused by but not limited to, a short to power, short to ground, disconnected cables, or the sensor is flat out junk. If this is the case, inspect the cables, sensor, and the connection between them, replacing any components if necessary.
A tip: If you wind up with a whole host of codes in the DTC chart, restart the software and turn the key off, then back on. Rescan. More often than not these codes are
false.
Here is a screenshot of what I ran into.
A tip: If you know someone who has a ranger similar to yours, see if they'll let you test their sensors with your multimeter and compare the results to yours.
Now a couple of you may be wondering what caused my ABS light. Well, it turns out the driver's side harness had been damaged, severing the wire. It was as simple as resoldering the wire.
I'll be wrapping that in some loom to protect it.
Good luck!