Intermittent Overnight Draw on a Vehicle With Aftermarket Electronics

Why 38 mA at ten minutes means nothing:

• Body and telematics modules can take 20-60 minutes to go to sleep. A reading taken during that window is measuring normal activity, not a fault.
• The 780 mA at two hours shows something is waking or failing to sleep later - and the 30 mA on other mornings shows it is intermittent. A single snapshot cannot characterize an intermittent draw; it can only prove the problem exists at that instant.

Conditions to control:

• Fully charge the battery first. A battery at a low state of charge can itself trigger telematics wake-ups and module keep-alives, which manufactures the very draw you are chasing.
• Key fobs out of range, all doors and the hood closed or door switches simulated without opening anything, no scan tool connected, no chargers attached to the battery during the measurement.
• Use a meter or probe that can log, and verify its low-range accuracy against a known load before trusting milliamps.
• Record battery voltage versus time alongside current so a voltage decay curve can be tied to the draw events.

Plan:

1. Baseline with logging. Connect a recording low-current meter or a current probe with logging, set a trigger above the acceptable threshold (typically 50 mA, confirm against the manufacturer's spec), and leave the vehicle locked overnight or for several hours. The goal is a timestamped event, not a snapshot.
2. Reproduce on command if possible. Check whether the draw correlates with anything - a fob being moved, a door being unlocked, the dash camera's parking mode, or an app being used.
3. Isolate the aftermarket first, non-invasively. Pull the fuses or in-line connectors for the dash camera and remote start. If the event persists, they are not the cause and you have not cut a single wire. If it disappears, you still must prove which of the two, and whether the install bypassed a module sleep signal.
4. Fuse voltage-drop mapping. With the draw active, measure millivolt drop across fuses - this identifies the branch without pulling fuses and waking the network. Pulling fuses resets modules and can erase the evidence, so do it last.
5. Document each step with time-stamped readings, because the fault may not repeat on the day you are testing.

Conclusion: the telematics module is the load, but not necessarily the faulty part.

A module that wakes on a schedule or on an external trigger is behaving as designed. Before condemning it:

• Check battery state of charge and capacity history. A marginal battery (5 years old, or repeatedly drawn down) can cause the telematics unit to wake on low-voltage events. The measured 660 CCA against a 700 rating on a warm battery does not prove cold performance - test at the rated cold temperature or load-test properly.
• Check for a software update or known issue for that module; a reflash is cheaper than a module and is often the actual fix.
• Verify the vehicle's duty cycle. A vehicle driven 10 minutes a day cannot replace what the telematics keep-alive consumes, and that math, not a failed part, may be the whole story.

Then:

• If the wake-ups persist after the battery is proven good and software is current, replace the module and re-measure with the same logging method.
• Re-verify total draw after the repair, and reinstall the aftermarket equipment one item at a time, re-measuring after each. The aftermarket installs were ruled out as the current cause but can still mask a return of the fault.
• Write the before-and-after milliamp numbers on the repair order.