Car Buyer Experiences mechanical Issue: 2015 Highlander, purchased from a dealership, failed to start after brief periods of inactivity. Upon inspection, a tracking unit was discovered, zip-tied to the radiator fan wiring harness.

Vehicle owners should be aware of potential hidden battery drains: gave a mechanic's cautionary advice. These invisible power-sucking devices could be in your car and they may be the reason why you should consider replacing your battery.

, and Administrator

2025 September 13 . 7:53 PM

2 min read

Car Purchase Issue: 2015 Highlander Refused to Start After a Few Days; Suspicious Tracking Unit... — Car Purchase Issue: 2015 Highlander Refused to Start After a Few Days; Suspicious Tracking Unit Found Near Radiator Fan Wiring Harness

Car Buyer Experiences mechanical Issue: 2015 Highlander, purchased from a dealership, failed to start after brief periods of inactivity. Upon inspection, a tracking unit was discovered, zip-tied to the radiator fan wiring harness.

In today's modern vehicles, hidden devices such as Progressive Dongles and OBD2 trackers can sometimes be the culprit behind unexpected battery drains. Here's a step-by-step guide on how to perform a simple parasitic draw test to identify any potential issues.

Preparation

Ensure your vehicle is fully charged or has a healthy battery before conducting the test.
Gather the necessary tools: a digital multimeter with DC amps and mA ranges, a small wrench for the battery terminal, a short 10- to 12-gauge jumper wire (or booster cable), and a fuse puller.

The Test

Start by opening the hood and blocking the hood latch with a screwdriver to keep the hood physically open while the car "thinks" it's closed.
Remove the keys/fob from the car and close all doors, locking them. Leave the vehicle for 30-45 minutes so all modules go to sleep.
With the vehicle off, unplug the Progressive Dongle from the OBD2 port and perform a baseline draw without the Dongle to measure the battery's normal draw.
Plug the Dongle back in and measure the battery's draw with the Dongle to determine the Dongle's added draw.

Interpreting the Results

The results can be interpreted based on the normal sleeping vehicle's draw (~20-50 mA). If the total draw with the Dongle is ≤ 60-75 mA, it may cause issues if the vehicle is parked for several days; a draw > 75-100 mA may cause issues, and a draw > 150 mA is likely to drain a battery quickly.

Safety Precautions

Never start the car or turn on high-current loads while the meter is in the amps mode and wired in series.
Work on the negative battery cable for safety.
Keep doors closed and dome lights off during the test.

Expert Insight

Timothy Boyer, an automotive reporter based in Cincinnati, emphasises the importance of understanding parasitic draws in vehicles. He researches and restores older vehicles, often incorporating engine modifications for improved performance. Boyer also covers modern cars, including electric vehicles, with a focus on DIY mechanics, tool use and selection, and other topics related to automotive repair.

Many mechanics recommend unplugging unnecessary OBD2 devices, especially in used cars where hidden trackers may already exist. Some insurance companies such as Progressive, Allstate, and State Farm install OBD-2 devices in customers' cars to collect performance or safety data for usage-based insurance programs.

By running a simple parasitic draw test, you can find out exactly what's leeching your battery life and decide whether it's worth keeping.