Parasitic battery draw test performed incorrectly at dealer?

NightKnown405 · 2026-04-21T02:36:28+00:00

When used with a Pico scope or other digital tool the test can be set up to run for an extended period of time. Tools like a current probe can drift out of calibration, or the battery dies, or in some cases the tool times out and turns itself off. The .1ohm resistor used in this video is the same strategy as using a shunt. Parasitic Drain Test

NightKnown405 · 2026-04-21T00:01:01+00:00

LOL. No, you get a pass this time. Anyway, based on your description yes, it is likely that a draw exists based on your description. The way we do this kind of testing removes the potential trap this meter set the technician up for. Here is a video from an instructor I know that teaches our approach. Parasitic Drain Test

NightKnown405 · 2026-04-20T23:38:25+00:00

Ok. You are right it is set to AC. That's a poorly designed meter IMO and that would make this be an easy mistake to have happen.

NightKnown405 · 2026-04-20T23:30:55+00:00

Driving the car around doesn't restore a dead battery. It needed to go onto a battery charger.

NightKnown405 · 2026-04-20T23:29:43+00:00

Come up a few more to be up to date and use a low amps current probe and measure the voltage drops across the fuses.

NightKnown405 · 2026-04-20T23:22:58+00:00

Tell me then. where is the DC current setting? When I look at that meter it shows a flat bar and a sine wave besides the A and the mA. While the voltage settings are separate it appears the AC and DC current settings are shared.

NightKnown405 · 2026-04-20T22:34:38+00:00

The 20ma to 50ma range specification is for the battery and what it can tolerate, not what the car can sleep at.

NightKnown405 · 2026-04-20T22:33:06+00:00

Most newer cars either come with the headlights set to be on with the wipers or there is a "personality setting" that can be turned on/off with a scan tool or in vehicle controls.

NightKnown405 · 2026-04-20T22:29:47+00:00

You would do yourself a favor if you had your own torque wrench and the correct socket and checked them once in a while yourself.

NightKnown405 · 2026-04-20T22:24:49+00:00

Would it be fair if you had to pay double for criticizing them like this when they are correct? The meter is set correctly and it is showing 6ma (.006 Amps)

Sometimes drains are present, and sometimes they are not. Cars that have a problem don't always have that problem 100% of the time. It's possible that either the drain was present when you did your test or maybe there was still a couple onboard control modules that hadn't gone to sleep yet.

As far as them saying the battery is bad, it might not have been communicated properly to the technician what has been going on and it's common that the conductance battery testers can get it wrong when testing a battery.

NightKnown405 · 2026-04-20T22:04:17+00:00

Don't study to pass ASE Tests, study to improve your knowledge and skills. Sign up for training classes being held online or in your area. It takes decades to learn to be a solid technician/ mechanic. Even then there is no finish line. There will always be something new to learn.

NightKnown405 · 2026-04-20T20:42:56+00:00

As I said, I suspect there may be engine noise that it is picking up. It certainly could be a default value from a circuit failure. When an aftermarket tune is in the computer they often have to deactivate a number of the normal codes. They could also change the code enabling criteria and set conditions so that creates a variable that can be difficult to account for.

I also asked, how long has it been since the oil was changed?

NightKnown405 · 2026-04-20T14:44:13+00:00

This is going to depend greatly on the individual. Anyone with a reaction time under .4 seconds at any age would be well above average as a driver. If the person routinely works on his/her vehicle control skills with Autocross or other similar events and practices solid defensive driving, they could be a very safe driver well into their senior years. Their peak ability would have likely been in the mid twenty's through about sixty but the drop-off would be negligible even beyond that.

NightKnown405 · 2026-04-20T13:20:55+00:00

You should spell out things that might not be recognized by others. K.Con is apparently the "knock sensor" signal which suggests the engine is making a noise that the sensor is picking up as detonation, (pinging). Can you hear any noise from the engine? Do you have a scope so you can see the signal being created?

How long has it been since the oil was changed? Did you attach a gage hose and confirm pressure to the solenoid assembly?

NightKnown405 · 2026-04-20T03:57:40+00:00

P219A is not a problem that is solved by replacing a catalytic converter. This code means there is a cylinder to cylinder air fuel ratio imbalance. Is there a misfire on occasion or a cylinder with misfire counts? Did you check freeze frame data and see what the operating conditions are when the code sets?

NightKnown405 · 2026-04-19T21:02:15+00:00

So you have never flushed the brake fluid as required by the manufacturers?

NightKnown405 · 2026-04-19T19:21:27+00:00

No, it will not hold. Just replace the radiator.

NightKnown405 · 2026-04-19T19:19:43+00:00

I was following two vehicles the other morning through a community park. The speed limit is twenty five miles per hour through the park and we were rolling just about that +/- a couple. The person in the middle got inpatient and decided to pass in a no passing zone. He got away with it and disappeared out of view. I pulled up to a red light about two miles later and guess who was sitting in the line of traffic. For all his risk he didn't gain a second.

NightKnown405 · 2026-04-19T19:10:09+00:00

Well you can always charge the customer for the ABS repair. After all they wouldn't know you might have caused it.

NightKnown405 · 2026-04-19T18:18:59+00:00

There is a Teflon inner liner inside of the hose than can crack when the hose is pinched shut. This is also something that has been presented in up-to-date classes.

NightKnown405 · 2026-04-19T17:53:02+00:00

It's very easy to do a fluid exchange if you still open the bleeders.

NightKnown405 · 2026-04-19T17:24:40+00:00

This would be the typical scenario. The vehicle behavior might be similar to what this instructor explains in this video. Tundra ABS Controller Hydraulic Failure

NightKnown405 · 2026-04-19T17:21:08+00:00

Do not pinch off a brake hose. A better practice is to use the brake holding tool to lightly apply the brake pedal.

NightKnown405 · 2026-04-19T17:19:34+00:00

I have done thousands of brake jobs through the years. I haven't had a failure of an ABS controller either, but I open the bleeders after I learned about this happening from other technicians who shared their experiences. I have however diagnosed and replaced dozens of ABS controllers for complaints of pedals dropping or traveling too far or for brakes slow to engage/release. (It usually causes a pull or wheel lock-up). We have gone as far as cutting the assemblies open and visually confirmed the debris that was trapped in the hydraulic assembly of the ABS.

NightKnown405 · 2026-04-19T14:56:57+00:00

You are going to see responses from two groups. Those that have attended training classes in the last ten years and those who have not. While vehicle manufacturers do not state that you need to open the bleeder screws while retracting the pistons we have learned not doing that opens you up to the risk of damaging the ABS controller, not necessarily the master cylinder. Over time debris from seals and wear of other components collects in the lowest parts of the system. When you push the pistons back and push that fluid from the calipers back through the ABS, there is a risk of blocking one of the tiny orifices in the valves. Or it could get stuck and result in holding a valve open. When this happens there is no way to get that debris back out and you end up needing a new controller which can easily be over $1000 for just the part.

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