Check Engine, TRAC, AND/OR VSC On? Read Me! - Page 2 - Toyota 4Runner Forum

BlackWorksInc · 06-09-2014, 02:02 AM

Quote:

Originally Posted by dustybutler1

I have a 2003 Forerunner 6 cylinder Limited 4-wheel drive 198K miles
I had a dead battery so I replaced it and the tow truck guy said the check engine light would be off and to go take it to AAA to get it inspected. I went to AAA Service and they said I had two error codes that were incomplete and to drive it 50-70 miles, which I did. Still had not cleared but before they did, the check engine light came back on so they reset it. They said the scan shows a 420 code (driver's side catalytic converter) but no other code. So I spent the next couple of days driving it, getting it retested, and same 2 INC codes for Cat and Evap System. I am now being told, not by AAA, that in order to get the Evap System to clear, I have to do a specific drive cycle, certain amount of gas in the tank, etc and I have to eliminate this 2nd incomplete error code to pass the inspection.

So is there some place that has the proper methodology to get thru the INC for the Evap System? Again, nobody has said there is any error code associated with the Evap system. Did it show up since I had my battery replaced? Can a mechanic clear this code or does it just have to reset itself by this proper drive cycle/amount of gas/etc requirement?

I know I need to get 4 new catalytic converters and probably oxygen sensors but the estimates are high and I really just need to get my car to pass this inspection since my registration has expired and I cringe every time I see the police.

Thanks for your time.

Dusty Butler
Durham, NC

I would change the AFR & O2 Sensors first before delving too much deeper into the P0420 if you can afford to at the moment. You would need to find out the EVAP DTC for us because its hard to say as there's more than one EVAP DTC that can set for any number of reasons.

There is a very specific drive cycle to get the monitors to set and its pretty tricky to do in a shop let alone at home. Typically a Toyota capable scantool can force an EVAP test to set the monitor, the rest usually sets within 60 miles of constant driving as long as the vehicle doesn't set a DTC.

Quote:

Originally Posted by Rommel

I have 20 OBD DTC readiness code and I already pulled the battery and plugged it back in. The truck doesn't have a CEL, but does anybody know if it will pass emission test? I'm thinking of replacing the O2 sensor or even the ECM too.

What do you mean "Readiness Code?" many OBDII "Code Readers" show a list of Monitors that show the status of OBDII Readiness Monitors on the vehicle. These are monitors used by the OBDII system and the Smog Technicians to pass or fail vehicles. You will always have them present with either a "Passed or Failed/Incomplete" message and is not directly indicative of a failure

When you disconnect the battery for any short amount of time or the DTCs are cleared via a scantool, the ECM loses memory of the Monitors and has to retest them, this is done so people cannot just clear a DTC and have their vehicles "pass" smog.

BlackWorksInc · 08-17-2014, 09:11 PM

Small bump, I updated a small section of the original post to include brief information regarding the C1201 DTC that sets when an OBDII DTC is stored and turns on the MIL. I have had a couple people ask me what it is and if it is something they should worry about.

On the 4th Generation 4Runners (this applies to a lot of Toyota SUVs, Minivans, and some cars as well) when an OBD-II DTC set and stored in the system, the MIL, TRAC, and VSC lights will always come on to indicate a fault in the OBDII System. If you have an ABS capable scantool you will see a DTC C1201-Engine Control System Malfunction, this DTC is always set when an OBDII DTC turns on the MIL; its the code that shuts off the VSC & TRAC systems and turns on the lights on the dash. Don't be worried about this DTC, when you correct the original DTC(s) that set the MIL on, the C1201 will erase along with the original codes with a scantool.

I also added a small section towards the end explaining what "Current" and "History" DTCs are, not everyone's code reader or scantool will pick this information up; but for those that do this should be helpful in determining where to start diagnostics.

I will also mention that some people may have scantools that indicate "Current" and/or "History" DTCs, these mean that the DTC was set by an issue that is occurring right now (Current) or that the issue has occurred in the past and the vehicle recorded the DTC for later review (History.) Typically only Current DTCs will set a warning lamp and History DTCs will simply show up when you do a health check; its important to know this distinction as you could pull up a History DTC for a problem and end up wasting time and effort trying to diagnose an issue that is not even present.

BlackWorksInc · 07-27-2015, 06:46 PM

Added a brief post note explaining why the VSC & TRAC systems are turned off when an OBDII DTC is set as I have seen this asked a few times and I realized I did not include it in my original post.

cnl390 · 07-28-2015, 03:28 PM

I am not a mechanic, but I can do some repairs on my own, and even if I can't I like to be somewhat knowledgeable when I do take my car to a mechanic. Can you recommend a moderately priced scanner that can be used with an android app. Or is a scanner with it's own read out the best choice?
Thanks

BlackWorksInc · 07-28-2015, 07:54 PM

Quote:

Originally Posted by cnl390

I am not a mechanic, but I can do some repairs on my own, and even if I can't I like to be somewhat knowledgeable when I do take my car to a mechanic. Can you recommend a moderately priced scanner that can be used with an android app. Or is a scanner with it's own read out the best choice?
Thanks

A lot of members like the "ScanGauge" tool, I know others have had good luck with "Chinese Toyota TIS Techstreams" on Amazon or EBay for less than $100 (they work almost as good as the factory scantool.)

If you search the forum you'll find a lot of threads on the topic.

cnl390 · 07-29-2015, 07:51 AM

Thanks. In the past couple weeks the MIL, TRAC, and VSC lights have come on a few times and I have reset them using a cheap bluetooth scan tool and Torque Pro. The lights have come on in the past and after resetting it would be weeks or months before they would come on again.

What scan info do I need to determine if it is a bad O2 sensor or a bad cat?

BlackWorksInc · 12-05-2015, 09:34 PM

Added a small section to address "Pending" DTCs and how they function to the first post.

Another type of DTC category you may see is "Pending", a Pending DTC is part of the "Two-Trip Logic" that OBDII dictates and some other modules use as well. Two Trip Logic means that the problem has to occur twice before the vehicle will set a "Current" DTC and turn on the MIL, a "Pending" DTC means that it has only happened once and the vehicle will not set an MIL on condition until it trips a second time and the DTC matures to a Current DTC (for example a P0420 or P0430 "Current" DTC means that the ECM ran the catalytic converter tests at two different times and returned two failure results, where as a Pending P0420 and/or P0430 means that the ECM ran the test and got a failure once and is waiting to see if it happens again before it sets the MIL and matures it to a Current DTC). Some modules such as SRS and ABS/VSC/TRAC do not use Two Trip Logic and will instead set a warning lamp on the first sign of an issue, these systems are "Single Trip Logic".

flash23 · 01-04-2016, 08:48 PM

Is there any way these lights could be connected to a wheel bearing needing replaced? I have an 06 that has a weird noise that, to me, sounds like it's coming from the rear. I took it to a shop and he said that the breaks didn't have an anti rattle clip, but the noise then went from a squeak more to a grind or something, like something needs lubed? I don't know. You can only hear it going slow, like 5-10 mph.

BlackWorksInc · 01-04-2016, 10:05 PM

Only if the wheel bearing failure somehow damaged the ABS sensor (very rare occurrence with how ours are set-up.)

flash23 · 01-04-2016, 10:46 PM

Thanks for the quick response. My cousin in law seems to think that the noise/lights are relating to my front driver wheel bearing, but I've never heard anything while driving to indicate that I gave one going bad. I was always under the impression that a bad one makes a roaring sound when you're driving.

bergs · 01-05-2016, 07:48 AM

Your cousin might want to consider not giving out automotive advice.

Slowgoat · 01-06-2016, 09:01 AM

@BlackWorksInc

We are lucky to have you here with us at the forum! Great info, and thanks!

Stunna1019 · 03-14-2016, 03:21 PM

I replaced gas cap, did zero point calibration and replaced o2 sensors and my VSC, TRAC and CEL lights are still on? Im not sure what else to do and how to get the lights off and stay off.

BlackWorksInc · 09-12-2016, 09:01 PM

Added a note to the "MIL OFF, TRAC ON, VSC ON" section about '03~'04 4Runners having the odd quirk of losing their ZPC memory from low battery voltage and occasionally from clearing DTCs. Realized I had forgotten to add this long ago when I was talking to a member about this very issue, still need to find a good "how to do ZPC" thread to link.

Elan750 · 10-27-2016, 10:06 AM

THis is a must read for people having emission related check engine lights:

http://www.autoserviceprofessional.c...leak-detective

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