'02 Check engine / TRAC OFF / VSC TRAC warning lights

Just bought a '02 4Runner and the check engine light and TRAC OFF / VSC TRAC lights came on just after a little bit of driving (they're constantly on, but don't flash).

I wonder if it could be related to another issue I've experienced with the brakes?
When braking at low speeds, just before stopping, the braking is very abrupt and the car shakes. It feels like when you drive on snow and the brake booster kicks in, it's the same noise and feeling. It comes and goes.

Where do I start troubleshooting? What can I check myself before taking it to a mechanic for a diagnosis?

 

First thing, make sure you're not seeing a stored code(s).
Either pull the EFI fuse for a minute or so, then re-install it, or pull the negative lead off the battery for a minute or so.
Drive your truck in a number of situations. IE: a slow, easy drive in town, a nice fast highway drive for 10 miles or so, long, easy acceleration hard, fast accelerations, long, gentle stops, hard fast stops, etc.

If the CE light comes on again, read out the code(s). If you need to, take it to a auto parts store. Most will provide you with a code reader for free.

The code(s) may well tell you the problems with the TRAC lights, and the troubleshooting procedure. Check the FSM.

Does this help at all?
Pat☺

 

Like @PhantomTweak says, try a code reader. I am no expert but for what it's worth, I've had those warning lights several times. (I have a 2001 SR5). Each time, it has been P0171 Toyota Fuel System Lean Bank 1. Not sure if this accurate, but my mechanic said when vsc warning lights go on with check engine, it's unlikely to be an actual TRAC issue but a way to make sure you don't miss the warning lights. Good luck and I'd be interested to know what you find.

 

Check the gasket on your gas cap, if it is crack replace the gas cap , it happened to my 2003 sr5, I replace the gas cap and the lights did not came back anymore, start with the cheapest remedy

 

My 2001 had this for years, and was identified as an evap code (same as the gas cap problem mentioned by sergie). I did everything from replacing the gas cap to O2 sensors, and finally gave up. Drove with those lights on for maybe 5 years or more.

One day, I was filling the tank, and heard some splashing. Looked under the truck to see gas flowing over the top of the tank. Here’s what I think happened: I religiously would fill up all the way into the filler neck to maximize my Kroger fuel discounts. I think years of doing that degraded the fitting between the tank and filler neck, eventually resulting in a break that allowed air in just like a bad gas cap would. Might also have contaminated the charcoal canister. Anyway, we drove it like that for over 100,000 miles. Not that I recommend doing that.

 

Thanks for the responses, here is the report that I got:
P0441 - EVAP System Incorrect Purge Flow Detected
It looks like a vacuum switch for the EGR valve.
I haven't noticed any issues with surging or rough idle etc. Should I just replace the EVAP vacuum switching valve? Looks like a $50 part and an easy job...

 

Yeah, I just replaced my entire EVAP system from the front of the tank back. Lots of hoses and lots of cracks. Easiest is to just get an entire charcoal cannister from TOYOTA, it has all new valves and hoses. Replaced everything in the tank. All Gaskets and Valves. Finally fixed my EVAP code for good. That was after I tried my gas cap. I think the issue was the gasket for the evap valve in the tank. But the hoses on the charcoal cannister were ready to give it up anyways.

OK, so this is REALLY REALLY bad to do. No one EVER do this.

1. It can fill up your charcoal cannister with fuel and ruin it.
2. Gas must have room to expand. Being a closed system, unlike classic cars, gas expansion when there is no air in the tank, in a modern fuel containment system, just blows out gaskets.
3. Gas is a solvent and over time extra exposure can mess up the rubber gaskets.

 

So he was close. If a code us thrown that even REMOTELY could affect the TRAC/VSC systems, they are disabled and the lights thrown. When I mean "remotely affected" it looks like TOYOTA determined that anything connected to those systems, if it is in fault, will cause the ECU to disable them. So since the ECU is connected to pretty much everything, a fault in the ECU (like the EVAP system) is going to trigger them to be disabled.

So he was right in that it's almost never anything to do with the Trac/VSC systems.

 

Hey,
I just replaced my battery after it died. The check engine light is gone now. Should I assume it will return again or could it be that the light came on just because the old battery was bad?

 

Electrical problems can be very odd. Your evap code is one that I don't think I see often so I would say that you may have fixed that issue. It may be indicative of a weak valve and may come back too.