Drove the RX300 into the mountains for a snowboarding trip and had to floor it to get up a steep incline. After flooring it all the lights on the dash lit up and the speedo and tach went to max and back to zero before returning to the speed I was travelling.

When the tach settled back to normal, the VSC and CEL lights were still lit up.

Checked the driving belt and tension , but the belt was tight and not worn. Checked the tension bolt on the driving belt and it was also not loose. There was about 1/4 inch of deflection. Could it be too tight or could the transmission speed sensor need replacement ? Anyone have similar issues ?

Any and all help is appreciated. TIA.

 

You have a 25 or 26 yr old work horse. Sudden increase in power from engine stresses the drive train and the old horse will quickly demise. I would say start shopping for an alternate vehicle, which would fit your need and driving style. RX were meant for soccer moms' needs. For controlling the transmission, you can turnoff overdrive [will kill your fuel economy]. If you just give more gas [more than just feathering but intentionally more gas,, the throttle position sensor will tell the ecu to shift down. RX and many other Lexus are a bit slow in responding but it will. Mashing down should be reserved for emergency situations.

Do you have a check engine light ON? Why I ask is that the lights you mentioned are also companion lights for number of CEL causing errors.

If not, then they stand for tires not spinning evenly. Nothing to do with engine belts, but actual tire to road contact. When you mash the gas pedal, you would have noticed your steering wheel try to turn on its own and that is a because the front wheels are not spinning in unison. [search torque steer]. Also the friction of the tires to the road is expected to match, but with sudden surge in power, coupled with tires conditions and the contact patch results in un-even rotation.

Salim

 

Salim[/QUOTE]

There was no snow or rain on the ground and the road was free of debris so loss of traction was not a problem. I've had this happen on multiple occasions when accelerating quickly, not "mashing" on the pedal.. and the flooring in this case was gradual, I eventually met the floor. I know I have an old car and drive it as such.

Any car, old or new shouldn't be flashing like this at any point in the drive. I was hoping to see if this was a common occurrence and if there was a fix for the issue other than buying another a car. Appreciate the feedback.

 

Without CEL, RX is simply detecting a wheel rotation difference. Although as a passenger you may feel there should be 100% traction, but there will always be a slip when there is abrupt change in power to the wheels.

If under normal driving the lights do no turn on then here are the things you can do to reduce the occurrence of the problem:

1. Check if all tires are the same [or match the opposing tires]. Same tread and condition.
2. Check inflation level ... 32psi is recommend but you can go down to 30 to improve traction but fuel economy will suffer.
3. Invest in tires with better traction ... they generally have shorter life span ... 20K miles or so.
4. Borrow or test another RX and try to have identical situation [having the same tires may be the hardest].
5. In a safe area turn off the traction and see what the vehicel nanny is doing. You will now experience the actual slippage. [Be careful, the vehicle will react unsafely and the onus will be on you to control]

You may disagree, but it seems what you experienced is typical of RX and for almost most Lexus models.

Salim

 

You've got a CEL so start with reading the codes

 

Yup , read it in the past and got a po500 for vehicle speed sensor malfunction. It'll clear on its own if I don't get on the gas too hard.

So it could be abs wheel speed sensor or the transmission speed sensors on the trans.

I'll run a live diag on computer to see which speed sensor is malfunctioning.

 

After live readings it's clear that the abs wheel speed sensors are fine. I replaced the transmission sensors for $10 a price and that didn't solve it either. Not sure what else could be causing the issue.

Maybe Salim is right about the functionality of an old system and this being common among Lexus models in this generation.

 

If you've got a P0500 do you also have an ABS light on? This was my experience: https://www.clublexus.com/forums/rx-...725-p1730.html
It was quiet for a few years and then happened again a few weeks ago, possibly because of all the snow. Cleared the ABS and DTC codes as described and it went away. No problems since.
I'm guessing the No. 1 vehicle speed sensor is the driver side front.

 

That's the thing, there is no ABS light that comes on and I did a live test of the wheel speed sensors, they all work properly. I'm thinking it's a wiring issue. The only lights that come on are the CEL and VSC and it lasts about 4 hours of driving and goes away on it's own if I don't gun it or floor it from a stop.

 

Which Autel scanner is that? Does it graph live data? It would be interesting to see how consistent the reported wheel speeds are as you gun it, floor it, and brake.

 

I think it does graph data, if not I could just use the live screen as a reference. All the sensors were operating pretty efficiently and consistently when underload and when off load.

 

Also gonna try just cleaning all the sensors of dust and debris and unplugging them and plugging back in to make sure the connection is solid.

 

I was on the wrong path .. I thought there is NO CEL.

If CEL is the issue [ignore other warnings]. Read CEL codes. Clear CEL.

Drive normally for a few days and if CEL pops up read again. Diagnose/trace the root cause of the CEL.

If after few days of driving no CEL, then stress <at your own risk> and ignore other warning signs and if CEL lights up, do a code read and diagnose/fix.

Once CEL [which typically is emission [there is more but back in mid 90's emission was reason to mandate OBDII port]

Not sure if I mentioned it, but having a good 12v battery and good alternator are a must before chasing faults. [I chased a ghost issue which was ABS related for 18months till I repaired my alternator]. Check battery hold-down and clamps. Sudden linear motion does not sit well with a loose heavy battery and causes strain on battery terminals and leads.

Salim