VSC/ABS Lights On, MIL Light Not On - No Codes?

Hello,

A couple weeks ago all 4 of the traction/vsc/abs lights came on in my 2005 v6 4Runner. The MIL/check engine light never came on. I took it to 3 autoparts stores and none of them could find any codes. I unplugged the battery (dumb mistake?) overnight to see if that would clear anything up. In the morning I plugged it back up and the same 4 lights were still on, they were on immediately as if it didn't even have to *think* about whether they should be on. I was expecting the lights to be off then come back on later once they detected the issue again. But this was instant. I don't know, just took me by surprise.

So here I am two weeks later, been driving it hoping the lights would turn off because maybe it was some bad fuel or something. No such luck. I ordered a mvci cable and installed Techstream to look for codes myself.

Running the health check shows no issues on the "Engine and ECT" and "Cruise Control" ECUs. When I looked at the available list of ECUs, "ABC/VCS/TRAC" and "Tire Pressure Monitor" were both marked as "ECU not supported or not responding". So I went over to the CAN Bus Check section and saw "Skid Control (ABS/VSC/TRAC)" was listed there. I didn't see an option to do a Health Check here, but did see a place for DTC codes. I saw no codes listed.

Any ideas what could be going on? I figured it wasn't the infamous gas cap since there was no MIL light, ever. And I may have mistakenly cleared all the DTC codes when I disconnected the battery, but its been 2 weeks and many miles - why are there still no codes?

Edit: I have checked all blade fuses I could find and they were fine. Tried zero point calibration and even though I got the lights to blink and *appear* to go through all the steps of the calibration, the lights remain on.

It’s most likely the brake light switch failing. Common problem , there’s a few threads on here with more detail.

lightfreak said:

It’s most likely the brake light switch failing. Common problem , there’s a few threads on here with more detail.

Click to expand...

Just went out and checked that switched. It has continuity between two posts in the open position and continuity between the opposite two post in the closed position. Just to be sure I took the switch apart, cleaned all the terminals, applied some dielectric grease, and retested and reinstalled. Started the 4runner and the lights remain on. Gave it a few minutes, turned it off then back on and the lights are still on.

Is there another way I need to test this switch?

Bought a new "stop light switch" today anyway. Installed it, the lights were still on.

Topped off the brake fluid reservoir (it was about 3/4 full) thinking maybe it detected low fluid. Still the lights were on.

Did the zero point calibration one more time and that didn't work either.

However, during the calibration I noticed the ABS and VSC lights were blinking in a rhythm. The abs was 3 blinks, a pause, then 1 blink. The vsc was 4 blinks, a pause, then 3 blinks. Did some reading and this is apparently a code meaning ABS 31 VSC 43. From what I've found, 31 refers to front right wheel speed sensor and 43 is just a side effect of 31. So I checked the front right (passenger?) speed sensor with an ohm meter and it was reading around 1200 but was very jumpy - a sign that its going bad? Then I tried the drivers side just for the heck of it - no reading - infinite resistance or whatever. So I'm going to try replacing these to see if that helps.

Any aftermarket ABS sensor recommendations or does everyone here go for OEM?

Also any ideas why this doesn't show in techstream?

I think you've nailed it. My money is on the drivers side reading OL. If the lights come on without having to "think about it", it's most likely not seeing resistance back from the sensor. Same as if it were unplugged. I just had this issue with the drivers rear sensor, only my problem was with the harness.

You can never go wrong with OEM. It might cost a little more up front, but only having to replace it once and peace of mind know it'll fit is worth it to me.

The code is coming from the abs or body controllers, I do t remember which. Tech stream is reading codes from the engine controller

Wanted to follow up on this and say that both the right and left front wheel speed sensors were bad. I forgot that about a year ago I replaced the front wheel bearings and tore up the OEM sensors in the process of removing them.
Instead of going back with OEM sensors, I got some cheap ebay sensors. So they lasted about a year, but were also 1/10th the cost of new OEM sensors. So I'm actually OK with that. But this time I went ahead and put the money out for OEM sensors, so heres to hoping they last the next ten years.

After replacing the sensors the lights were still on. I did a zero point calibration and that turned all the lights off. We had just gotten some snow the day before so was a perfect time to test and verify all the abs and vsc systems were working again.

Also, I wanted to list the ohm readings of the good and bad sensors just for reference if anyone ever needs the info:

Both new OEM sensors read 1750 ohms
One of the bad sensors read 1200 but bounced around a lot. A few days later it was reading 450.
The other bad sensor read nothing or infinity, however you look at it.

Also know that typically after you make the repair, you can drive it around, maybe a couple hundred feet in both directions, and the lights will go out.

Just want to add for noobs like me, check the brake fluid level first like Jonnie Blaze mentions. I had an ABS light on, the "brake" light on and the swerving car symbol on my 2013 4runner, but no DTC present. Added brake fluid and drove about 1/4 mile and lights went off. Need to check brake pad wear now. Dave