Connect with confidence

SET UP
THE TEST.

Choose from 32 equipment and test guides covering electrical, fuel, mechanical, cooling and air systems.

Multimeter workflow

Select the correct function: DC volts, resistance, frequency or current.
Connect the black lead to COM and the red lead to the fused input required by the function.
Back-probe the circuit without spreading terminals; reference the specified ground.
Measure at rest, during operation and under load, recording min/max values.

Before you measure

Never measure resistance on a powered circuit.
Use a fused current input and verify its rating before series testing.
Compare supply and ground at the component, not only at the battery.

Electrical & oscilloscope tests

Power-Side Voltage Drop

Locate resistance in a loaded low-voltage power path. This does not test a circuit’s capacity while it is switched off.

Loaded Ground Voltage Drop

Check whether a low-voltage ground path carries operating current without excessive loss.

5 V Reference Circuit

Check a regulated sensor supply and identify shared-reference faults. A correct reference alone does not prove the sensor works.

Parasitic Draw — Current Clamp

Measure key-off current and sleep behavior without disconnecting the battery. One short observation cannot rule out an intermittent wake-up.

Starter Current and Cranking Voltage

Compare starter demand, battery voltage and cranking behavior on conventional low-voltage starter systems.

Alternator Ripple

Inspect the repeating AC component on a conventional alternator’s DC output. Ripple alone does not identify every charging fault.

Hall-Effect Digital Signal

Check a powered switching sensor’s supply, ground and output. This guide covers a digital Hall implementation, not every Hall sensor.

Variable-Reluctance Signal

Evaluate a passive inductive speed/position sensor during target movement.

Solenoid Current Ramp

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

Relative Compression — Starter Current

Screen for unequal cylinder loading during cranking. This compares cylinders; it does not measure absolute compression or prove all cylinders are healthy.

CAN Resistance and Termination

Check termination and wiring on a confirmed two-terminator high-speed CAN segment. This does not verify communication quality.

CAN Signal Quality — High-Speed Bus

Inspect high-speed CAN physical signaling. A plausible voltage pattern does not prove message content or module function.

Fuel-system tests

Low-Pressure Fuel Supply

Verify fuel supply pressure at the specified point. Pressure alone does not establish adequate delivery volume.

Fuel Pressure Under Load

Check whether supply pressure follows demand when the complaint occurs.

Fuel Residual-Pressure Leak-Down

Measure pressure decay after shutdown. Decay alone cannot identify which component leaks.

Fuel Delivery Volume

Measure fuel quantity delivered over time at the prescribed pressure. Free-flow volume is not equivalent to delivery under pressure.

Port Injector Balance — Pressure Drop

Compare relative flow using equal injector commands and equal starting rail pressure. This is not a GDI or diesel injector test.

GDI / Diesel Rail Pressure — Command vs Actual

Evaluate high-pressure control using scan data without opening the high-pressure system.

Diesel Injector Return-Flow Test

Compare injector return flow using the specified common-rail test method. Return flow is not injected fuel quantity.

Mechanical tests

Cranking Compression — Gauge

Measure cylinder pressure during cranking. Interpretation depends on engine design, temperature, cranking speed and test procedure.

Cylinder Leak-Down

Identify cylinder leakage paths while the piston is stationary at the specified position.

Intake Manifold Vacuum

Assess manifold pressure behavior on a suitable engine. Vacuum patterns are clues, not a unique diagnosis.

Running Compression

Compare cylinder pressure behavior while other cylinders run, using an engine-specific approved method.

Crankcase Pressure / Ventilation

Evaluate crankcase ventilation and pressure under defined operating conditions.

Cooling & air-system tests

Cooling-System Pressure Test

Locate coolant leakage with a controlled static-pressure test. A static pass does not rule out a hot or load-dependent leak.

Cooling-System Pressure Cap

Check cap pressure relief and, where supported, vacuum-return operation.

Combustion-Gas Test — Cooling System

Screen coolant-system vapor for combustion-gas contamination. A negative result may miss an intermittent leak.

Intake Smoke Test

Locate unmetered-air leaks in the selected intake section with regulated smoke.

Boost / Charge-Air Leak Test

Check the isolated charge-air path for pressure leakage without operating the turbocharger.

Exhaust Backpressure

Measure upstream exhaust pressure to investigate restriction. It does not by itself identify the restricted component.