Caution...vsc/trac Disabled.

[wwest]

During the recent snow and ice storm here in the Seattle area I noticed that my 2001 AWD RX300, 60,000 miles, was not "acting" quite right. In situations where the VSC/Trac would have normally activated they did not. So I did a couple of "test" runs in an empty parking lot and sure enough the front wheels would spin free with the engine RPM rising accordingly. Also "throwing" it sideways did not result in VSC activation, only the little instrument light (no beeping) on indicating a skid.

No real problem as I soon had tire chains on all four.

Last week I contacted the service advisor at Lexus of Bellevue who proceeded to advise me, profusely, that the VSC/Trac system will always be operational unless an indicator is lit on the instrument panel indicating otherwise. When I persisted he insisted that it was probably working and I wasn't familier enough with its actions to know.

So I fired off an email to customer_satisfaction_inquiries@lexus.com.

In response I was told to contact a dealer.

Over the weekend I got out the shop manuals and discovered that the ABS was indicating codes 31,32, and 33, apparently a temporary or intermittent failure of both front wheel speed sensors and one rear wheel sensor, and VSC was indicating a code of 43, ABS control failure.

According to the manual the ABS will continue to work with these codes but it was unclear, undefined, as to what the result would be with the VSC code 43.

So I contacted Lexus of Seattle and after a long discussion I was told that a VSC code 43 would result in the VSC/Trac system being non-functional but that there should have been a VSC failure indication on the instrument panel. The Lexus Lexus technician suggested that I might have inadvertently ignored the failure indication for enough drive cycles that it would have extinguished.

I'm quite sure, VERY sure, there was never an indication of VSC or Trac failure on my instrument panel for multiple drive cycles. When I suggested that the firmware might be flawed in that no indication was displayed the technician allowed that the 2001 was the first year of VSC/Trac implementation on the RX series but refused to speculate further.

He did tell me that the wheel speed sensor faults could result from ordinary wheelspin that occurs in low traction conditions.

So I have cleared the fault codes but have not yet been able to test the VSC/trac system for operational capability.

[RXHound]

WW, thank you for chronicling your experience with the VSC. I was wondering how to check to see if it is really working as I never see any indications on the instrument control panel and one rarely if ever has it function in normal vehicle use, unless in icy weather. I would guess the 2003, that appears to be the third year of this feature, has any upgrades available.

I rarely get to test mine, as you did in a parking lot in snow, but I plan to do so as soon as the snow arrives.

[wwest]

WW, thank you for chronicling your experience with the VSC. I was wondering how to check to see if it is really working as I never see any indications on the instrument control panel and one rarely if ever has it function in normal vehicle use, unless in icy weather. I would guess the 2003, that appears to be the third year of this feature, has any upgrades available.

I rarely get to test mine, as you did in a parking lot in snow, but I plan to do so as soon as the snow arrives.

Other than the "groaning" or "rat-a-tat" of the braking, which aren't really always audiable, the indicator light and beeping sounds are the only way to tell if the system has activated. Since the indicator goes out and the beeping stops as soon as the VSC/Trac ceases operation it is sometimes hard to tell that it has activated absent having someone else to watch the instrument panel while you concentrate on driving.

[gp1200x]

If you can clear the codes and they do not reappear and your light is off, then your system may be operating, but if any sensor code exists (reappears) after resetting it and the light is on, that system will shut itself down. Any malfunction of a sensor or the ECU itself could cause an accident so the system cannot activate if a current sensor error is active.

This is the only vehicle I have ever owned that had an ABS failure, every other vehicle never had any problems...

and I am not a big fan of ABS since it some circumstances it takes the control of the vehicle out of my hands

[wwest]

If you can clear the codes and they do not reappear and your light is off, then your system may be operating, but if any sensor code exists (reappears) after resetting it and the light is on, that system will shut itself down. Any malfunction of a sensor or the ECU itself could cause an accident so the system cannot activate if a current sensor error is active.

This is the only vehicle I have ever owned that had an ABS failure, every other vehicle never had any problems...

and I am not a big fan of ABS since it some circumstances it takes the control of the vehicle out of my hands

Haven yet had any re-occurance of failure indication so I have checked the underlying diagnostic codes. I'll do that next oil change. Insofar as VSC/Trac is concerned to the best of my knowledge I've only had VSC activate one time unexpectedly and traction never. All other times were in conditions wherein it was expected and "prepared" for mentally.

Personally I have always felt that ABS should NEVER activate unless the VSC sensors indicate that the vehicle is not following my desired direction of travel.

[wwest]

20F on the eastside of Seattle and all roads are quite throughly iced over.

This morning as I pulled the RX out of the garage and down our driveway the traction portion of VSC was hard at work. A short distance down the road I had to back up a slight incline but the RX was no go even with traction control active and the rear wheels driving. After a very short period of trying to back up the incline the CEL came on along with VSC fault indication.

Now I had no traction control as an assist and all I could do was spin the front wheels.

So I got out and disconnected the battery for a slow count of 30 and sure 'nough the fault indications were off and I was able to more gingerly, with traction control now again active and clearly being of some help, back the RX up the incline and be on my way.

For the moment I suspect the CEL was/will be the result of a too lean mixture, itself resulting from the extended period of engine dethrottling by the traction system. I'll hook up this scan gage after I get back home this evening and post the results.

P0500 "Vehicle speed sensor"

Apparently the yaw sensor/accelerometer was used to compute that the vehicle wasn't moving as fast as the speedometer was indicating.