Triple ISO Tester

Advanced circuit tester for testing
your truck’s ISO 7638 Socket,
Trailer Susie, and ABS Functions


ISOTester is an advanced diagnostic device for testing a truck’s ISO 7638 socket, trailer Susie lead and ABS functions for short or open circuits. By running a simple series of tests the ISOTester quickly identifies fault details and the location (tractor unit, Susie lead or trailer), which is not always easy to locate.

  • Tests truck’s ISO 7638 socket
  • Tests ISO 7638 Susie lead
  • Tests vehicle’s ABS functions
  • Reveals missing/faulty ABS warning light
  • Quick to setup
  • Easy to interpret LED display
  • Powered by tractor unit’s ISO 7638 socket
  • Durable construction
  • UK designed & manufactured

How the tester works

When you plug the tester in, it will test all the pins against each other for live and earth. The tester is to be powered by all the pins except pin 5. If led 1, 2 or 5 are green it means there is a good live above 19.5 volts, but if they are red it means the live is below 19 volts. If led 3 or 4 are green it means a good earth but if they are red it means a bad earth.

Testing the ISO 7838 Susie Lead

The ISOMASTER is plugged into the trailer end of the Susie lead, while the other end of the Susie lead is connected to the truck as usual. The LEDs indicate the test result as per the key printed on the side of the unit.

Testing the truck's ISO 7638 Socket

The ISOMASTER is plugged into the truck’s ISO 7638 socket and the ignition is switched on. If all 5 LEDs light up green this indicates a pass. If one or more LEDs light up red the fault can be diagnosed using the key printed on the side of the unit.


EBS/ABS Sensor and Exciter Ring Tester

For testing and indentifying sensor, gap and exciter ring faults on any EBS/ABS system.


Lightweight, portable and simple to operate

The SensorMaster is supplied with a 1.6m high quality cable and a separate universal adapter for those applications where the standard lead’s termination is not applicable. The SensorMaster comes ready to use straight out of the box.

The SensorMaster is compatible with 90% of applications as standard. It works with any ABS/EBS system made by Knorr Bremse, Haldex or Wabco fitted to any type of commercial vehicle whether it be truck, trailer, bus or coach.

The SensorMaster tests for the following causes of sensor related faults:

  • Correct OHMS resistance
  • Open Circuit
  • Short Circuit
  • Pole ring tooth damage
  • Pole ring mis-alignment
  • Sensor gap measurement


Heavy Duty Power

Portable 24 Volt Power Box with auto light test for testing your trailer electrical system. Designed to enable one operator to test the complete trailer lighting system using the 24N and 24S power sockets, and to test the ABS warning lamp function on the trailer using the ISO 7638 socket.


Self-contained 24 Volt Power Box in robust lockable case, with three switchable power sockets (24N, 24S, and ISO 7638) voltmeter, plus switches and warning lamps to test all the electrical functions on your trailer sockets to the Power Box. Battery-charging lead. The batteries inside the Power Box provide the 24 volt supply, and are re-charged using the battery-charging socket on the side of the Power Box.

How the auto light tester works:

Connect the 24N and 24S sockets to the trailer, then turn on the test switch. The lights will come on one at a time in a pre-set order for 12 to 15 seconds.
When the test is finished, any lights that were in the ‘ON’ position at the start of the test will come back on again.
When the test is running, if there is a short circuit in any of the lights being tested, the box will automatically turn off the power being delivered to that light and go on to the next light in the sequence.
If the trailer lights are wired in parallel, when the test starts both right and left side lights will come on.