1997 Lexus amp draw (1 Viewer)

[dbfrink]

Interesting issue that my mechanic is struggling through currently-
I recently picked up a 1997 Lexus FZJ80, 176k miles. The PO hardly drove it, putting ~20k on the clock since buying it from the original owner in 2005. I paid what I believe to be a good price in spite of a couple mild issues.

One issue was an amperage draw that would kill the battery if left overnight without a trickle charge. The PO added a lot of aftermarket electronics- remote start, kenwood amp and subs, ceiling mounted DVD player for the rear seat, and a Jensen stereo system with a large screen. The battery is 2 years old, and tests very well (it’s been on a maintainer overnight for its entire life).

My mechanic first removed the amp and subs and the remote start because they were pulling a draw. The draw seemed to be about 45milliamps after that, which seemed reasonable. I took it home, same issue, so I took it back in. It has been with the shop for several weeks now, and regardless of what system they unplug- audio, dvd, etc- the battery drains overnight. The amp and remote start have been pulled entirely.

Tried a new battery, still drained.

It’s not a huge inconvenience to leave it trickle charging overnight, but I am ultimately prepping it as a camp vehicle/light overlanding rig and will need the battery to maintain. My long term plan is to add a second battery and solar panels, but want it to be gremlin-free before messing with the electrical system further.

Thoughts? Anything stand out as a next thing to check?

 

[jonheld]

If a draw of 45mA kills the battery overnight, then that battery is faulty.
Typical current draw should be 20 to 30 mA, so 45 is high, but not enough to drain a good battery in a few hours.

Have the battery tested and measure the load again.
Edit:
If you replaced the battery with a new one and it's draining overnight, then your load is quite a bit higher than 45mA. I suspect it was not measured correctly.

 

[leonard_nemoy]

Get a new mechanic, these constant threads about mechanics not being able to solve problems like this blows me away.

Tracking down a parasitic draw like this should be a basic no brainer for any decent tech. Does your mechanic even know how to use a multimeter?

This should be a simple diagnostic proceedure requiring nothing more than knowledge of multimeter use and access to the battery and fuses.

The fact that your mechanic is using the trial and error method of unplugging different aftermarket items and hoping to find the cause of the draw using this shot in the dark approach also makes me think you need to take it to a different tech.

Here is a youtube video that shows the correct way to diagnose a parasitic draw. If your really a nice guy you could show this to your mechanic and teach him how to do his job.

 

[dbfrink]

Get a new mechanic, these constant threads about mechanics not being able to solve problems like this blows me away.

Tracking down a parasitic draw like this should be a basic no brainer for any decent tech. Does your mechanic even know how to use a multimeter?

This should be a simple diagnostic proceedure requiring nothing more than knowledge of multimeter use and access to the battery and fuses.

The fact that your mechanic is using the trial and error method of unplugging different aftermarket items and hoping to find the cause of the draw using this shot in the dark approach also makes me think you need to take it to a different tech.

Here is a youtube video that shows the correct way to diagnose a parasitic draw. If your really a nice guy you could show this to your mechanic and teach him how to do his job.

That is fair.
I do trust the shop owner, who is a friend. He admitted today that he is taking the project over from one of his employees because it should’ve been solved by now.

 

[LandLocked93]

Just a quick check...
Ensure that the cable - connecting the alternator to the battery - is not shorting out on the alternator case.
I found this to be my issue. I have charge and discharge monitors in my truck and noticed a huge draw (>500mA, truck off, key out) after messing with the alternator-to-battery cable, at the alternator-end of the connection. The OEM wrap around the cable's terminal can split on the underside (not immediately visible), causing an arc that should be visible while you move that cable around when the truck is running.
I heat shrinked a couple more wraps around the terminal body and all is good.

 

[TNOverlander]

I too had a parasitic draw when I got my LX450. I’ve had two since having it actually though I don’t think either would drain it overnight. The first was the factory CD changer in the console. Removed cd changer and problem solved. That one has been the problem for a few owners. The next was the factory cell phone stuff. That one I just removed the fuse for the cell phone stuff and left it out. Might be a couple lx450 ones to check.

Ultimately though it’s an easy process with a multimeter as others pointed out. You can also do it yourself even without a multimeter with a small bulb instead of the multimeter (also keeps you from blowing your multimeter fuse if it’s a bug draw). Same method just get a small marker light bulb and pigtail. Bulb will light up bright in series with batter my cable if you have a parasitic draw. When you remove the offending fuse it will dim or go out entirely.

 

[dbfrink]

Appreciate the input.

I didn’t think it should be this tough to track, but frankly, I have steered clear of electrical issues in my wrenching.

Most of my personal wrenching time is spent on my pre-1980 bikes, and since this is my new daily, I figured I’d pass it along to someone I expected to be more qualified.

The shop owner was supposed to work on it this weekend himself. Hoping there’s some resolution by tomorrow, otherwise I’ll just go the trickle charge route til I can sort through it.