Automotive Test Lamps and Multifunction Testers

Frequently Asked Questions About Automotive Test Lamps and Multifunction Testers

The following frequently asked questions address key points regarding the use of automotive test lamps and multifunction testers. They explain which electrical tests can be performed, what the limitations of their use are, and how these devices differ from multimeters and other diagnostic tools.

• What is a multifunctional automotive test device?

  A multifunctional automotive tester is used for quick troubleshooting in a vehicle's electrical circuits.
  
  Depending on the model, it can be used to check polarity and continuity, verify ground connections, and test the functionality of relevant electrical components.
  
  In addition, voltage or ground can be applied selectively via the test probe.

• What can be tested using an automotive test lamp or a multifunction tester?

  Typical applications include testing the following:

  • Cables and wiring harnesses
  • Fuses
  • Switches
  • Relays
  • Diodes
  • Lamps and lighting
  • Fuel pumps
  • Power window motors
  • Ground connections

  This allows many faults in traditional vehicle electrical systems to be pinpointed directly on the vehicle.

• What is the difference between an automotive test lamp and a multimeter?

  A multifunction tester is particularly well-suited for quick functional, polarity, continuity, and ground tests, as well as for selectively activating compatible electrical components.
  
  A multimeter, on the other hand, provides specific measurement values for electrical quantities such as voltage, current, or resistance.
  
  For a comprehensive diagnosis of automotive electrical systems, these two testing devices can therefore complement each other effectively.

• What voltage ranges do AZ 172 and AZ 173 cover?

  The AZ 172 is designed for electrical systems ranging from 6 to 24 V.

  The AZ 173 has an operating range of 12 to 24 V.

  For vehicles with a traditional 6-V electrical system, the AZ 172 is therefore the appropriate model.

• Can the AZ 172 also be used in classic cars with a 6-V electrical system?

  Yes. The AZ 172 has an operating range of 6 to 24 V and can therefore be used for appropriate tests on standard 6-V vehicle electrical circuits.
  
  The respective vehicle and component specifications must be taken into account.

• What is the difference between AZ 172 and AZ 173?

  Among other things, both devices allow for polarity detection, continuity testing, ground testing, and functional testing of suitable electrical components.

  The most important difference lies in the voltage range:

  • AZ 172: 6–24 V
  • AZ 173: 12–24 V

  The AZ 173 also features test point illumination and an audible polarity indicator.

• Can the testers be used to determine polarity?

  Yes. Polarity is indicated by a red/green LED.
  
  With the AZ 173, polarity is also indicated by different audible signals.
  
  This makes it easy to quickly determine the electrical potential at each test point.

• Can relays be tested using a multifunction tester?

  Yes. Relays are among the typical electrical components that can be tested using AZ 172 and AZ 173.
  
  In addition to the continuity test, voltage or ground can be applied to suitable components to check their function.
  
  Before testing, the pin assignment, operating voltage, and permissible current draw must be known.

• Can fuel pumps or window regulator motors be tested directly?

  Suitable electrical components, such as fuel pumps, window regulator motors, relays, or lights, can be supplied with voltage or grounded using the multifunction tester.
  
  This makes it possible, for example, to determine whether the component itself is functioning properly or whether the fault lies in its power supply or wiring.
  
  The technical limits of the tester and the respective component must be observed.

• How can poor ground connections be identified?

  AZ 172 and AZ 173 enable the testing of ground connections in conventional automotive electrical circuits.
  
  This allows, for example, broken or faulty ground connections to be pinpointed more quickly.
  
  A suitable multimeter can also be used to quantitatively assess a voltage drop under load.

• What does the resettable 7.5-A thermal fuse mean?

  AZ 172 and AZ 173 are equipped with a resettable thermal fuse rated at 7.5 A.
  
  It protects the tester in the event of an overload or short circuit and can be reset after tripping.
  
  However, this protective function does not replace the need to observe the permissible current consumption of the component under test.

• Can a short circuit be detected using a multifunction tester?

  The test device can assist in troubleshooting suitable conventional vehicle electrical circuits and, for example, respond via its protective circuit in the event of an overload or short circuit.
  
  However, a systematic short-circuit diagnosis must always be performed while taking into account the specific circuit, the wiring diagram, and the vehicle manufacturer’s specifications.
  
  Voltage must not simply be applied to control modules or sensitive electronic signal circuits for this purpose.

• Can AZ 172 and AZ 173 be used in control units?

  No. AZ 172 and AZ 173 were developed for use in conventional automotive electrical systems.
  
  They are not intended to apply voltage or ground to control modules or sensitive electronic circuits.
  
  For such diagnostic tasks, appropriate measurement and diagnostic equipment must be used.

• Can the testers be used for CAN bus diagnostics?

  AZ 172 and AZ 173 are not intended for the actual diagnosis of CAN bus communication lines.
  
  To test CAN bus systems, use appropriate diagnostic tools, multimeters, breakout boxes, or oscilloscopes—depending on the specific test task.

• Can vehicle inspection lights be used on electric and hybrid vehicles?

  Use only on suitable low-voltage circuits within the specified voltage range and in accordance with the vehicle manufacturer’s specifications.

  AZ 172 and AZ 173 are not high-voltage testers and must not be used for work or measurements on high-voltage systems.

  High-voltage systems in electric and hybrid vehicles require measuring and safety equipment specifically designed for this purpose.

• Can the testers also be used to test trailer lights?

  The 6-meter-long connection cable allows you to reach electrical test points that are farther away.
  
  This makes it possible, for example, to test the appropriate circuits in a trailer’s lighting system.
  
  Specialized trailer and tow vehicle testers are also available for systematically testing a trailer or a trailer receptacle.