How to Test for a Parasitic Draw

As an Amazon associate, we earn from qualifying purchases.

Parasitic Draw Test

Sometimes, a battery may experience significant drain long after the engine has been shut off. It might not be a faulty battery causing this. Instead, this typically happens due to a short circuit that can be hard to pin down. It could be anything from a dimming dome light left on or a glove compartment switch sticking on, to a faulty aftermarket radio or alarm wiring.

Also, any number of electronics systems that are installed on newer cars could be acting up, such as your GPS or proximity key system.

What you will need

A basic digital multimeter is best for this test as opposed to an analog one, which isn't as accurately read.

Testing for a parasitic draw, which refers to an excessive electrical current draining from a vehicle's battery when the engine is off, can be done using a multimeter. Here's a step-by-step guide on how to use a multimeter to test for a parasitic draw.

How To Test A Parasitic Draw With A Multimeter

1. Prepare the vehicle:
- Park the vehicle in a safe and well-ventilated area.
- Ensure all lights, accessories, and electrical systems are turned off.
- Wait for at least 20 minutes to allow the vehicle's modules to enter a sleep mode 2.

2. Set up the multimeter:
- Switch the multimeter to the DC ampere (A) mode.
- Set the range to a suitable value higher than the expected current draw (usually in milliamperes or mA). Start with a range of 10A if available.

3. Disconnect the negative battery cable:
- Open the vehicle's hood and locate the battery.
- Using a wrench or socket, loosen and remove the negative (-) battery cable from the battery terminal.

4. Connect the multimeter:
- Connect the multimeter leads in series between the negative battery terminal and the negative battery cable. Connect the red lead to the battery terminal and the black lead to the battery cable.

5. Monitor the current draw:
- With the multimeter connected, observe the reading on the multimeter.
- It's normal to see some initial spikes as modules wake up, but within a few minutes, the current draw should stabilize.
- Take note of the current draw reading. If it exceeds the manufacturer's recommended specification (usually around 20-50 mA), there might be a parasitic draw.

6. Locate the source of the draw:
- Begin narrowing down the source of the parasitic draw by removing and replacing fuses one at a time.
- As you remove a fuse, monitor the multimeter reading. If the current draw drops significantly after removing a specific fuse, that circuit is likely the source of the draw.
- Consult the vehicle's owner manual or wiring diagram to identify the systems or components connected to the circuit with the parasitic draw.

7. Investigate and resolve the issue:
- Once you've identified the circuit causing the parasitic draw, inspect the associated components or systems for any signs of malfunction or wiring issues.
- Perform necessary repairs or seek professional assistance to address the problem.

8. Reassemble and retest:
- After resolving the issue, reinsert any removed fuses and reconnect the negative battery cable.
- Double-check that all connections are secure.
- Perform the same current draw test again to ensure that the parasitic draw has been eliminated or reduced to an acceptable level.

Remember, if you're unsure or uncomfortable with performing these steps, it's recommended to seek assistance from a qualified automotive technician.

Which Tools are Best for a Parasitic Draw

Innova 3320 - The Entry-Level Choice

• Features: The Innova 3320 is an auto-ranging multimeter that is ideal for those new to automotive electrical diagnostics. It includes features like auto-ranging scales, which eliminate the need to dial in the correct range when making electronic measurements.
• Suitability for Parasitic Draws: With its ability to measure down to milliampere levels, the Innova 3320 is suitable for identifying small currents that could signify a parasitic draw. Its ease of use makes it a popular choice for DIY enthusiasts and those who need reliable, straightforward diagnostics.
• Safety: This product is UL-Listed, certified for safety and quality.
• Accessories: Comes with testing probes, built in stand and wrist wrap, and protective rubber guard.
• Price: It’s currently being sold at $36.99.

The following measurement types and ranges are available for the Innova 3320:

The Innova 3320 digital multimeter can be purchased on Amazon.

This tool can be used for the following automotive use cases:

• Automotive Circuits
• Breakers
• Wiring
• Vehicle Battery
• Charging Systems
• Electrical Components
• And More

It can also be used for various home improvement projects!

Innova 3340 - The Professional’s Tool

• Features: Designed for professional use, the Innova 3340 offers more advanced features, including a temperature probe, inductive clamp, and a higher level of precision. This multimeter also includes min/max and hold functions to capture signal fluctuations during testing. Easily save and reference retrieved data.
• Suitability for Parasitic Draws: The precision of the Innova 3340 makes it exceptional for diagnosing parasitic draws, allowing technicians to detect even the slightest discrepancies in current that could indicate issues. Its robust construction and additional features support frequent, intensive use in a professional setting.
• Safety: This product is UL-Listed, certified for safety and quality.
• Accessories: Comes with testing probes, RPM clamp, protective rubber guards, and a carrying case.
• Price: It’s currently being sold at $102.99

The following measurement types and ranges are available for the Innova 3340, with more flexible ranges compared to the Innova 3320:

The Innova 3340 digital multimeter can be purchased on Amazon.

The Innova 3340 is especially suitable for automotive diagnosis, with the following measurement types and ranges available:

How Does Innova Compare to Other Parasitic Draw Tools

Innova’s Industry Legacy and Innovation

• Long-Standing Expertise: Innova has been developing automotive diagnostic tools for more than 30+ years. Innova is ISO 9001 certified. This extensive experience translates into a deep understanding of automotive technology and user needs, ensuring that each product is both effective and easy to use.
• State-of-the-Art Research: Innova collaborates with ASE Master Technicians to conduct cutting-edge research and development. This partnership ensures that all Innova tools are up-to-date with the latest automotive technology standards and are capable of handling a wide range of diagnostic challenges, including intricate parasitic draws.

Product Features and Guarantees

The Innova 3320 and 3340 exemplify Innova’s commitment to quality and efficiency. Both are equipped with features tailored to detect parasitic draws effectively:

• Innova 3320: Ideal for hobbyists and DIY users, providing reliable measurements with auto-ranging capability.
• Innova 3340: Meets professional standards with enhanced features like a temperature probe and inductive clamp for comprehensive diagnostics.

Customer-Centric Guarantees

• 1-Year Warranty: Innova products come with a one-year warranty, covering any defects or issues that might arise.
• 30-Day Money Back Guarantee: Customers can return products within 30 days for a full refund if not completely satisfied, highlighting Innova’s confidence in its product quality.
• Quality Guarantee: Each tool is rigorously tested to meet high standards of performance and reliability.

Innova Versus Other Brands

• Precision and Reliability: While many brands offer tools for electrical diagnostics, Innova’s products are renowned for their accuracy and dependability, crucial for tasks like detecting parasitic draws.
• Super Safe: All Innova multimeters are UL listed and certified for safety. Other brands may not have the same safety guarantees as Innova and may result in electrical damage.
• Innovative Features: Compared to other tools, Innova multimeters often include more advanced features that enhance diagnostic capabilities without sacrificing user-friendliness.
• Customer Support and Warranties: Few competitors match Innova’s comprehensive customer support and warranty offerings, making it a preferable choice for both novices and professionals. We speak fluent English and Spanish, available Monday - Friday, 6AM - 6PM PST.
• Going 30+ Years Strong: Buying from us gives you a peace of mind knowing that we’re here to assist you and provide product support as needed. There have been cases where some diagnostics companies discontinue their products, resulting in zero support.
• Proudly American: Innova is an American company based in Southern California that supports local car communities and promotes sustainable manufacturing practices.

Conclusion

Congratulations! You’re now aware of what a parasitic draw is, how to properly diagnose it, and know the best tool to successfully resolve it. If you’ve read this far, I have no doubts that you’re on your way to becoming an expert DIYer.

We encourage you to go beyond multimeters and try OBD2 scanners as well! As one of the leaders in the diagnostic industry, we build advanced diagnostic scanners made to streamline your repair process. Available in both English and Spanish.

Give Innova a try today and let us help you diagnose your problem, faster.

Back To Blog Academy