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-   -   One cause & fix for "VSC TRAC" & "VSC OFF" lights, Zero Point Calibration (https://www.toyota-4runner.org/problems-and-warranty-issues/32818-one-cause-fix-vsc-trac-vsc-off-lights-zero-point-calibration.html)

MicaBlue03 12-10-2007 03:12 AM

One cause & fix for "VSC TRAC" & "VSC OFF" lights, Zero Point Calibration
 
If you suddenly have the "VSC TRAC" and "VSC OFF" lights in your dash, this post may help you fix the problem yourself. The information here applies to 4th gen 4Runners that use the ISO protocol rather than the newer CAN protocol for their OBDII interfaces to code readers, ECU programmers, hand-held testers, etc. The OBDII interface includes several different protocols (methods of digital communication) and they all use the same physical connector, though with some different pins. The connector is located at the bottom of the dash on the driver's side and in the 4Runner it's covered by a small black cap.

4Runners switched from ISO to CAN around 2005 though this information may also apply to newer 4Runners with some modification. That is, newer 4Runners may display trouble codes and reset sensor calibration values in response to the connection of different (than earlier 4Runners) pins together than the ones described below.

Several posters have discussed similar problems, described in several different threads. I'm reluctantly starting a new one, with a more specific title (including the exact name of the two trouble indicator lights), in the hope that searchers will more easily find a solution.

The specific behavior: On startup, the "VSC TRAC" and "VSC OFF" lights come on and stay on. The ABS light may or may not come on. On subsequent starts the lights will come on temporarily as usual (as a bulb check) and then go off. They come on again and stay on as soon as the 4Runner is moved. The "check engine" light does not come on. This behavior begins after the vehicle has been hooked to some sort of OBDII code reader or engine tester or data logger, etc. Though the lights are on, no standard OBDII problem codes are detected by a regular code reader.

Cause: The code reader or other OBDII device has attempted to communicate with the 4Runner using the CAN protocol (involving pin #14) and this has caused the 4Runner to erase the "zero point calibration" numbers in its memory. Without these numbers it can't get accurate information from the yaw rate and deceleration sensors (in the center console near the gearshift) and so it disables traction and stability control functions.

The fix: Perform the "zero point calibration" procedure as described in TSB BR001-04. This procedure can be performed without special equipment such as a hand-held tester or OBDII reader. You only need the equivalent of a jumper wire to short together two pins of the OBDII connector at the right time and the right number of times between switching the 4Runner on and off. More detail is included below, leveraged from my other posts.

Why this doesn't happen every time a code reader is used: The code readers usually use the pins and protocol of the OBDII connector in a specific sequence, trying first to establish communication with the vehicle using the oldest protocol. They then try the pins and protocol of newer protocol standards. Usually the code reader would be successful in its first try at establishing contact with the 4Runner using the ISO 9141-2 protocol, and there would be no problem. However these communications schemes are not foolproof and occasionally the ISO protocol attempt fails. Then the code reader tries newer protocols including CAN (controller area network). It's this CAN attempt, which toggles pin #14 (the CAN data pin) that accidentally tells the 4Runner to erase the existing zero point calibration data. Since the 4Runner (this vintage anyway) can't communicate by CAN protocol the tester re-tries the older protocols again and eventually succeeds in setting up communication by the right ISO protocol. But by then the calibration data has been erased.

The calibration, by the way, is simply a matter of telling the 4Runner VSC/TRAC computer "your yaw rate and deceleration rate are currently zero" and to save the associated values. Then the output from the sensors can be interpreted correctly.

Detail (may be helpful if you're going to do the calibration procedure yourself): The SST (special service tool #09843-18040) specified in the service manual appears to be essentially a Y-shaped test lead and is variously called a "jumper wire" or "diagnostic check wire." It's used in this case to repeatedly connect and disconnect the chassis ground (CG, pin #4) and Ts (pin #14) terminals of the OBDII connector (referred to as DLC3 in Toyota-speak). The connection/disconnection sequence and timing are described in the service manual and in several TSBs. OBDII connector diagram and pin descriptions are in TSB BR005-03.

Since the OBDII connector is at the lower edge of the dash and pointing down (right above your left foot when you're sitting in the driver's seat) it's rather tough to reach in and do the shorting to the appropriate terminals of the OBDII connector with a test lead. Especially since you're supposed to avoid moving or shaking the vehicle when you're doing this. BTW, the OBDII connector usually has a black snap-on cover over it to keep out grit, etc.

Therefore I took a couple of pieces of insulated wire about 24" long each and taped them alongside each other, and stripped both ends. To make the wire fit securely in the (female) terminals of the OBDII connector I soldered a 3/8" length of metal (cut from a heavy paper clip) to one end of each of the wires. I chose a pin size so that would fit securely in the female terminals of the OBDII connector but wouldn't distort them. I used some heat shrink tubing around the solder joint to reduce any chance of accidental shorting.

After plugging the two pins into the OBDII connector (with the other ends held apart) I was able to hold the other ends of the two wires in my hands and touch them together at the appropriate times to connect the pins of the OBDII connector. I had a helper in the passenger seat to read the instructions from the TSB to me in sequence.

This is not very hard to do, and one need only be careful. It's easier to do with the Toyota OBDII tester, of course, and would only take 5 minutes. You might be able to get your dealer to do it gratis, but you might also be charged some minimum labor hour rate.

BTW #1: Doing the sulfur TSB or others that require the replacement or reprogramming of the engine computer or the VSC computer will also require this calibration.

BTW #2: I verified that when the lights are on the VSC and traction control are indeed inoperative. ABS is working, though.

BTW #3: Shorting other pins (such as #13 Tc) at the right time can cause the appropriate dash indicators to blink in sequence to reveal trouble codes other than the OBDII ones. A generic OBDII code reader won't give you this data, and you need the service manual (physical or online) to make sense of it. I believe there is a specific code to tell you that the zero point calibration data has been lost, but I didn't look for it.

BTW #4: In the 4Runner of this vintage the OBDII connector pins populated are 4, 5, 7, 9, 13, 14, 15, 16

[Sorry about the long post, but I wanted to include the kind of information I'd want if I encountered this problem and wanted to feel comfortable fixing it myself]

Falkon 12-10-2007 04:55 AM

1 Attachment(s)
Thanks a bunch MicaBlue03.

Glad you could clarify the alternatives to some of the special tools - SST. Could you show a picture of how your wires were plugged into the DLC3, please?

To further assist with your writeup, I have attached the TSB, BR005-03, you mentioned in your script. A schematic of the DLC3 unit indicating the required pins TS and CG with the re-calibration instruction is shown on page 7 of the attached TSB.

Good Luck.

Falkon 12-14-2007 07:42 PM

I tried performing the Zero Point calibration the other day on my T4R and observed that when I touched the CG & TS wires 4 times per the TSB instruction, that, both my ABS light and the VSC Trac light began to flash. I continued regardless and completed the procedure but my lights are still on (VSC TRAC and VSC TRAC OFF). I have repeated the calibration several times but no luck. Any ideas please?

kgray01 12-17-2007 12:46 PM

Had the same thing happen
 
Just had the same thing happen. Driving and out of the nowhere the 2 VSC lights and the check engine lights came on. Took it to the dealer. Just got the call and it was the driver side catalytic converter that was bad. Still covered by the factory, but would of been $1,100+ if it was coming out of my pocket. CRAZY.

Falkon 12-17-2007 03:40 PM

VSC TRAC & VSC OFF Lights
 
Finally got mine sorted out and will very much like to thank everyone in this forum, you guys are great.

The Stealership was insisting that my Yaw Rate Sensor was bad and needed to be changed at a cost of $885 (parts only). I showed them a hard copy of the TSB but they also wanted to charge $133 for the Zero Point Re-calibration regardless if it was going to be helpful or not. :confused:

So I got a contact of one ex-Toyota Service Tech who now has his own shop, took my T4R to him and, in less than 5minutes, he got everything sorted at zero cost. Amazing!! had to give him something for beer though which he reluctantly obliged.

Took my ride out for a spin and the VSC now works again like a charm. phew!!!!:D

MicaBlue03 12-18-2007 02:23 PM

I can't figure out why a bad catalytic converter would cause the stability/traction control to stop functioning, but others have reported this as well. That doesn't seem like good design on Toyota's part.

The bad converter does turn on the check engine light, though, and that reminded me of advice I've heard from several sources: If you've got the check engine light on, read the standard OBDII trouble codes and look at that stuff first.

Code readers of several types are getting cheaper, and I think it's a good idea to have one if you're going to do much of your own work or if you hope to learn more to protect yourself from incompetent or dishonest service departments. If you've read the code yourself you can sometimes stop the service folks from selling you a load of something you don't need. Also, the code readers can often be used to reset the check engine light to see if the problem was a isolated event.

The regular code readers can't do everything that the Toyota-specific testers (typically at dealerships) can do. That includes programming new keys and reading or resetting a bunch of Toyota-specific parameters. Fortunately some of that Toyota-specific stuff can be done by manipulating pins of the OBDII connector and watching lights in the instrument cluster. Instructions are in the service manual, and you can get temporary access through alldata.com if you don't want to buy those expensive volumes.

All this applies to the pre-CAN bus 4Runners. I don't know if things changed after the bus protocol switch--maybe others who have the service manuals can enlighten us.

chiplee 02-02-2008 01:30 PM

Quote:

Originally posted by Falkon
I tried performing the Zero Point calibration the other day on my T4R and observed that when I touched the CG & TS wires 4 times per the TSB instruction, that, both my ABS light and the VSC Trac light began to flash. I continued regardless and completed the procedure but my lights are still on (VSC TRAC and VSC TRAC OFF). I have repeated the calibration several times but no luck. Any ideas please?
same thing happened to me. Before trying the calibration I could reset the ecu and make the lights go off. After the calibration the lights stay on even after reseting the ecu. strange. The test went exactly as described in the tsb but the abs light came on

V8Limited4wd 02-10-2008 12:21 AM

I just did this and it worked perfectly! I'm so glad I didn't have to take it to the dealer for them to mess with it and probably charge me for it.

kurt_dogg 02-27-2008 04:46 PM

What if the lights only come on intermittently?
 
I have these same symptoms of the VSC TRAC/VSC OFF (only) lights coming on.

They only seem to come on & stay on during a very cold start, as in, 1st thing on a good Canadian winter morning. Ironically when the VSC is needed most. Of course I can re-start & the lights do not stay on again because the truck has warmed a little, but who wants to do that all the time.

What is the relationship between cold starts & the VSC system disabling itself?

kurt_dogg 02-28-2008 12:43 PM

I sent an e-mail to the dealership describing this issue & here is there response:


[QUOTE]We are aware of a problem with the VSC during freezing temperatures, however doesn

MicaBlue03 03-24-2008 12:18 PM

kurt_dogg, it sounds to me like the system isn't getting good data from the yaw/deceleration sensor when that sensor is really cold. The sensor is in the center console and can cause the traction & stability control to be disabled, though ABS likely still works.

It could be a bad sensor unit (they're both in the same package) or it could be an electrical connection that's intermittent at cold temp.

Short of tearing into the vehicle to check the sensor and wiring, it does seem like a good idea to check the diagnostic code(s) when the problem has occurred, or perhaps to try the zero point reset. It could be that there is some long term drift in the sensor and when it's cold its output is skewed enough to cause the computer to flag it as bad and show you the lights.

If you have access to the repair manual set it has procedures to short pins on the OBDII connector to cause lights to flash in the cluster to give you some of the Toyota-specific diagnostic codes. That could tell you if the problem is bad data from the yaw/deceleration sensor or no data, or something else entirely.

Espino66 07-19-2008 12:42 PM

One cause & fix for "VSC TRAC" & "VSC OFF" lights
 
Thanks so much for the advice for fixing the "VSC TRAC & VSC OFF" lights problem on a 2004 4Runner, 875000 miles. The dealer quoted around $850 for a yaw accerleration sensor and $300 labor. The dealer insisted that my sensor is bad and must be replaced. Even after I told them that the vehicle only needed the "Trac zero point calibration" precedure. I showed them the bulletin that specifys the procedure and they would not budge.

My problem started after I purchased a 2007 Camry and pretty much park the 4runner. I decided to drive the 4runner one day and it would not start. I used a cheap jumper cable (use good quality jumper cables) that somehow shorted out and blew the ECU fuse on the 4Runner. After I recharged the battery, the check engine, VSC TRAC & VSC OFF stayed on and the vehicle would not go more than 10 -15 mph. I called the dealers and they wanted $90 just to run diagnostics. I went Auto Zone and they run a diagnostic for free. That is how I found out that the ECU fuse was bad. I replaced the fuse and the "check engine" light problem was fixed but the VSC TRAC & VSC OFF were still on. I went to the dealership and they were fully convinced that the problem was the yaw & accerelation sensor and it must be replaced and I was quoted $1200.

Today, I used speaker, about 18 inches long, and followed the direction very crefully and closely in TB and fixed the problem in about 5 mins. It is easy. They key is to follow the direction very closely and you can perform the "Trac zero point calibration" . Thanks again for the information. It save me $1200. One can only imagine the number of people who pay taht sum of money needlessly. It is a rip off to say the least.

rbmatl 10-07-2008 06:10 PM

Thank you
 
Kudos....I just came over from a Jeep Cherokee. Used 04,,,VSC and Trac lights came on after an emissions test that used the ODB. Stelership wanted $110 to do the zero point calibration. Took 2 minuites with speaker wire. You guys are worth the price of admission.

rook 10-07-2008 10:00 PM

We need to make this a sticky.

PezDSpencer 10-14-2008 01:20 PM

A debt of gratitude
 
Thank you MicaBlue03!!!

Followed your instructions and all is well.

I can keep my kidney as opposed to trading it for a new yaw sensor.

Thanks again!!

Jason D
Northampton, PA


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