17/06/2026
Ford Ranger - ABS light on.
This was another one for 4D Automotive Solutions Ltd today.
This Ford Ranger has been plagued with an ABS warning. The vehicle has been to numerous workshops with no real resolution. Simon asked us to take a look as it has previously has a sensor but is no different.
Once we got the vehicle into the workshop, we read the codes and confirmed the fault. Next, we got the multimeter out, and volt drop tested the Left Front sensor. We found there was only a 0.5v drop across the sensor. Then we disconnected the sensor, and the voltage jumped to 3.5v. Unsure whether this is a 5v or 12v system, we tested the opposite wheel, this confirmed it should be 12v.
Armed with this information, we went back to the offending wheel. We reconnected the meter and started to wiggle the wires, we found the voltage jumped to 5v. However, this still isn't enough, and this told us there is a high resistance somewhere.
The next step now, was to resistance test the circuit. So, we disconnected the ABS unit and gained access to the back of the plug. With the sensor disconnected, we tested the resistance of each wire between the ABS unit and speed sensor. We found that one wire had a good value of 0.5 Ohms. However, the second wire had a whopping 40 Mega Ohms (40 Million).
With the information we had, we offered the owner a few different options.
Option 1: Replace the harness with a new one (this would be parts & labour intensive and very expensive).
Option 2: We could start to pull back the wiring harness to find the exact point of failure and repair (again very labour intensive and expensive).
Option 3: Not the nicest looking repair, but definitely the most efficient. We could cut the wire at each end and then add our own wire in place (overlay the wire). This saves hours of labour and is ultimately the cheapest and probably the most reliable repair (without replaceing the entire loom).
Armed with the information, the owner opted for option 3. This is the most cost effective method and usually the preferred method by most owners. So, we cut the wire, and added a new length between the ABS unit and sensor. Once the repair was made we retested the system and found a full 12+ volts at the sensor.
A quick road test confirmed the fault was fixed and no more warning on the dash 👍.
