First off, I haven't had time to fully troubleshoot these issues, because of the holidays and other reasons. And today I'll be driving my Highlander to Florida for a couple of weeks, so I won't be able to troubleshoot it until I get back.

Several weeks ago, I had the ABS light come on in my Tacoma after a rough off-road climb up a very rocky and steep hillside. When I got to the bottom and unlocked my rear locker, the ABS light stayed on instead of going off like it normally does. Disconnecting the battery for a while and reconnecting it did no good.

Last week, I noticed my check engine light was on too. The truck runs fine, except for a slightly slow idle at 500 RPM when in gear, which I think it's been doing for a while.

Then a few days later, when not running and the headlights off, I noticed that when I would push the brake pedal, the instrument panel lights would come on, as well as running lights, although a bit dim. With the headlights on, truck running or not, everything else looked fine. That is, until I noticed my right side brake light was burned out.

I replaced the burned out right side brake/tail light bulb a couple of days ago. The mysterious panel light/driving light issue went away. Although I'm an industrial electrician/instrumentation/controls tech and understand electricity very well, I'm having trouble understanding why.

At first I thought there might have been moisture in the bulb socket, causing a connection between the tail light positive and the brake light positive that allowed just enough current to flow that the other lights dimly lit. But that's not the case.

The mystery gets even more mysterious...

Yesterday, I noticed that both the ABS light and check engine light are now off. And all I did was replace the right side tail/brake light bulb.

I don't have a code scanner for it, but I'm thinking of buying one after I get back from Florida. Until then, does anyone have any experience with this sort of thing?

 

for codes: go to an auto-parts/napa/o'rielys/zone store. they can check it for free.

 

You have been away from simple DC circuits to long.

What happens most times is something is trying to ground back through the tail light circuit could also be going through the ABS circuit as well.

Have a good trip to the land of the ORB`S

 

Yes, I considered that once I realized that there may very well be a common cause. Just like I considered the possibility of moisture in something like a bulb socket causing the instrument panel glow with the brake lights on, since at the time I had no reason to suspect a common problem causing the ABS light and the check engine light. Further troubleshooting would require me getting back home from vacation.

 

Yea, but I'd rather have my own code scanner for times when there's no auto parts place handy.

And the auto parts guys often don't know what they're talking about. Like, for instance, if a code shows an O2 sensor sensing a lean mixture. They'll often try to sell you an O2 sensor rather than see if there's another problem actually causing a lean condition. Because O2 sensors are often actually working right.

 

then you need a bluetooth obd2 scanner from e-bay. they are cheap (less than 10 bucks) and easy to use. if you have a smartphone, download any obd2 scanner app(s) and read the codes. if you want to use a computer, you'll need a bluetooth usb adapter (less than $5) and have the computer in range of the car (laptops work best for obvious reasons)

also, you can ask the auto parts store guy for the codes, write them down, and search online later. if you want a truly free way to look up codes.