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Current Clamps for Automotive Diagnostics

12 March 2019 14:45

Current clamps are also referred to as clamp-on current probes or Amp clamps in America. They enable you to measure currents without breaking the electrical circuit. Current clamps feature opening and closing jaws that can be placed around a wire (conductor) where a magnetic loop is formed.

Current clamps can either be connected to an Oscilloscope with a BNC Test lead or Multimeter through a Banana Plug Patch Lead. The specification of Current Clamps varies on; Amp Ratings, AC/DC functionality, Jaw size and display system. It’s important to match instrument specification with intended use to ensure accurate and reliable electrical testing.

Here we look to explore and explain why the Current Clamp is an important and versatile instrument that every Automotive Technician should have in there tool box.

Why use a Current Clamp in Vehicle Diagnostics?

Current clamps prevent the need to break an electrical connection, remove terminals or pierce the insulation conductor to carry out circuit testing. This helps improve the working safety of the technician and reduces the time spent undertaking electrical circuit testing. Current can be measured anywhere on a circuit and proves the power supply or the ground reference is active. Testing with a current clamp also ensures that components remain installed and tested in their designated working environment. Testing a fuel pump for example relies on many different factors which would be impractical to create if the pump is removed and tested externally. 

Automotive Current Clamp 600A DC (High Amps)

Vehicle High AMP Current Clamp











Automotive diagnostics relies on accuracy and one of the great skill sets when testing sensors and using different tools is to try and capture the information in the best possible place. If you measure current in a series of events and measure the current once and then apply it to different components then that reduces the amount of moving around and connectivity, saving time and improving cost-effective practices.

Many current clamps offer the ability to adjust sensitivity or attenuation of the clamp for different diagnostic tests. Two current ranges controlled by a selector switch refines the tests and ensures the technician identifies the signal he/she requires to analyse performance of the component under test.

Current clamps offer a safe, cost-effective, simple and accurate way to take current measurements when diagnosing automotive electrics.

Automotive Current Clamp 60A (Low Amps)

Vehicle Low Amp Current Instrument 



Vehicle Diagnostics Applications with Current Clamps

  • Non-intrusive diesel injector tests;
  • Testing ignition coils;
  • Crank Current Testing;
  • Turbo Actuator Current Testing;
  • Ignition profiling;
  • Fuel pump testing;
  • Common rail pressure sensor testing.

Current Clamp Accessories & Essential Equipment 

The current clamp has a wide capability when used for vehicle diagnostics, however it does require additional equipment to perform well. The digital measurement instrument choice is pivotal to how the data is represented and the accuracy of tests conducted. 

  1. Digital Multimeter - The Fluke 87V Multimeter is an Automotive diagnostics favourite which will accurately display clear and simple numerical information. It’s used effectively for quick and reliable routine diagnostics.

  2. Automotive Oscilloscope - Complicated tests like ignition profiling and fuel injection issues are best identified and resolved using a handheld or PC based Oscilloscope such as a Carscope, Picoscope, TiePie, Bosch KTS, Hantek Scope etc.

  3. Fuse Extension Breakout Set - They create a temporary and reliable access point to a circuit by enabling the connection of a current clamp and perform tests on a fused circuit. Read more about Fuse Breakout Extensions.

  4. Automotive Connector Breakout Leads - Experience secure reliable connections and lose the back-pinning probes. Find out why Bosch ACS Breakout Leads pave the new way for vehicle diagnostics.

  5. BNC Test Leads - Convert 4 mm Plugs to a BNC Oscilloscope connection with easily identifiable and durable BNC Test Leads.  

  6. Automotive Plug to BNC Adapter - The PJP 7043-IEC is a toolbox essential and is frequently used by technicians converting connection leads from standard banana plugs to BNC interfaces.