What this test proves

Compare electrical current buildup with a solenoid’s command. Electrical evidence alone does not prove correct fluid flow or mechanical output.

Tools

  • Low-current clamp and automotive scope
  • Rated voltage probe if observing driver voltage
  • Circuit-specific specifications

Preparation and precautions

  • Identify the solenoid and driver type before testing. This guide excludes piezo injectors and HV actuators.
  • Secure the mechanism and follow pressure/temperature precautions. Do not apply battery voltage directly without an approved procedure.

Connections

  • Clamp one solenoid conductor. For voltage, use the approved reference or differential connection and a probe rated for inductive turn-off voltage.

Equipment settings

  • DC current with correct clamp scaling. Capture a complete on/off event; use an edge trigger and a range above expected peak. Voltage probes must tolerate the driver clamp transient.

Test sequence

  1. Zero the clamp and capture the specified command.
  2. Compare initial rise, peak/hold or PWM behavior and turn-off.
  3. Repeat with an equivalent working circuit under matching conditions.
  4. Confirm mechanical response or flow using the relevant test.

Expected signal / readings

Current rises as the coil energizes. Some designs show a movement-related change in slope; PWM or peak-and-hold control alters the shape. An inductive voltage transient may occur at turn-off.

Interpreting results

  • A missing movement feature is not conclusive unless the design normally produces one.
  • Low or absent current can result from feed, wiring, coil or driver faults.

Common mistakes

  • Treating every solenoid as peak-and-hold
  • Using an unrated voltage input
  • Assuming electrical activation proves valve flow