VSC light will not reset

[tim hunter]

Hello

I have an 02 SC430 and have used the usual paperclip procedure (jumping between the Ts and CG pins) many times to reset the VSC light, over the years.

However, I now have the two VSC lights, and the ABS light on, and the reset is not working.

So, while the car was off the road over winter I had all four ABS sensors out for cleaning, and replaced the front nearside which broke during removal. It also had new rear discs.

After reconnecting the Battery I now have these three lights.

If I add the paperclip and turn on the ignition, the lights stay on and do not start to blink.

I borrowed a professional Snap-on code reader, which found no codes in any system in the car. All the dash lights went out too.

However, as soon as I drove it the VSC lights came back, and first touch of the brakes brought back the ABS light.

 

Any suggestions? Hard to proceed with apparently no error codes at all!

 

Regards

Tim

[oldjoe]

had the same ,turned out to be front O2 sensor off side (uk). A broken connection on the plug connecting loom to sensor lead. Have also seen same fault be a faulty sensor.

[Mihanicos]

The skid control ecu is normally connected to the instrument cluster via CAN and multiplex communications. If the VSC is off, the indicator light will come on.

Check the communication system, the multiplex communication system, the ecu connector, the VSC switch and the harness connection between the skid control ecu and the VSC switch.

Battery voltage should not fall below 10 v.

For the ABS light to stay ON, the skid control ecu connectors are disconnected from the skid control ecu.

A malfunction of the ecu control.

An open circuit in the harness between the instrument panel and the skid control ecu. 

To locate and identify the fault, you need the techstream to perform various tests and measurement and to retrieve all the codes. The freeze frame is a great help and it will guide you with additional codes pertaining to the time before and during the fault occurrence.

Chris.

 

 

[tim hunter]

thanks for the replies.

Next I tried a zero point recalibration - which successfully cleared the lights. However, half a mile down the road, they came back on again.

Josef - how did you conclude it was an O2 sensor? My OBD reader displays real time graph data for all four sensors, and they appear to be responding as they should.

 

Chris  - do you have any procedures to actually do any of the diagnostics you suggest please? I got a techstream adapter and software from the web last year, but never had much success making it communicate with my 2002. Do you have a known version that may work?

 

Thanks and regards

Tim

[Mihanicos]

I have the MongoosePro by Drew technologies of America. This gives access to dealer level diagnostics, programming, software updating etc. This is approved  by Toyota and it can read all models from 1992 to date, irrespective of market destination.

I think that some techstream versions available on various websites have limited features.  

Snap on have excellent diagnostic tools whose performance varies according to model.

From what you are saying, it seems that the VSC module may have failed. Check the resistance of each abs sensor and their connectors to the car harness. Make sure the contacts are clean.

I assume that all your tyres have exactly the same size, if you have different size tyres this will trigger the ABS light and may be VSC light too.

Chris.

[tim hunter]

thanks for the reply. All tyres are same brand and almost new.

I am tending to think it is ABS related, since that is the work I did on the car over winter. Both front sensors were very reluctant to be removed and I broke the left one, which is replaced with a new Holstein unit. The right side was also very difficult and looked okay, but I wonder if it was damaged. Anyway, I just ordered a new one from Rock Auto. Should be here is a week or so, and we shall see then. Odd that the Snap-On code reader showed no ABS issues though - which I tested specifically.

Best regards

Tim

[Mihanicos]

Ok, measure the resistance of the abs sensors and check that the slots opoosite the sensors are clean and their gaps are even. Remove any rust or anything sandwitched in between any gap. The resistance values should the same for each pair at the front and for the rear. A small difference between the front sensors resistance and the rear is acceptable. 

If the VSC module is damaged, it will light up the ABS and the VSC.

Chris.

[tim hunter]

Hello again

  the ABS sensors were removed over the winter for cleaning because the ABS was kicking in under gentle braking at 10mph. Dirty senders are a common cause of that. The rears were covered in iron filings - presumably bits of disc surface and pad. They came out easily, were cleaned and put back. Both fronts were very very stuck, but looked clean when removed.

Anyway, the second front sensor arrived the other day and is now fitted - so that's both fronts are brand new and matching brand. I did the zero point reset and all lights were out. Half a mile down the road, and they all came back on again. Also, after driving twenty miles or so, and restarting after a rest, the brake warning light is also on now. The car drives and stops absolutely fine.

Finally, I also have a Bank 1 Sensor 1 fault code on the Lambda, which appears after around 50 miles. That sensor was replaced last year because of the code, but it is still recurring.

All very frustrating really.

[Mihanicos]

F For the ABS light to remain on this may be due to :

Air in ABS unit.

The skid control ecu connectors have bad contacts.

There is a malfunction in the skid control ecu.

There is an open circuit in the harness between the instrument cluster and the skid control ecu.

Check the CAN  communication between the instrument cluster and the skid control ecu.

If you decide to remove the skid control ecu, disconnect the negative cable from the Battery and wait 2 minutes before proceeding. This will prevent airbag deployment.

For bank 1 sensor 1, check the wiring and harness to it, clean contacts and make sure the wires in the connectors are secure and not damaged. These sensors last for a very long time, the problem may be in the circuit.

Chris.

[oldjoe]

On 4/8/2021 at 12:13 PM, tim hunter said:

thanks for the replies.

Next I tried a zero point recalibration - which successfully cleared the lights. However, half a mile down the road, they came back on again.

Josef - how did you conclude it was an O2 sensor? My OBD reader displays real time graph data for all four sensors, and they appear to be responding as they should.

 

Chris  - do you have any procedures to actually do any of the diagnostics you suggest please? I got a techstream adapter and software from the web last year, but never had much success making it communicate with my 2002. Do you have a known version that may work?

 

Thanks and regards

Tim

found the info on Lexus World, it seemed to be quite common. Another thing to check are the reluctor rings on the rear. take out the sensors and check the state of the rings by looking in through where the sensor fits. Make surse they are not worn down, even partly. Can be a bit of a job to replace, had mine done by Rich (lexusman) on lexus world.

[Mihanicos]

Intermittent faults are very hard to find. To find any fault, you need the detailed circuit diagram of your car showing all the connectors, their location and their wiring. A good diagnostic tool should be able to read all the codes too so you have a very good idea what you are looking for.

The principle of operation of the various components in this case is normally the same with most models of the same production years.  My car is a different model to yours.

From what you are saying, you seem to have a bad intermittent connection  in the circuit of the system. Check for damage to the wire harness connecting the various equipment of this circuit, especially where any body or mechanical repairs have been carried out in the past. Check also the ground connections of the equipment involved, main ecu, skid control ecu and car chassis. Make sure that all connectors have clean contacts and all pins are straight.

Chris.

 

 

[Repair1]

Hi ,I had vsc,abs,and take warning lights on when I put diagnostic on it ,it came up with both rear abs sensors faulty ,bought a set off eBay fitted them problem solved

[Mihanicos]

 Thank you very much for the update. I am sure you will enjoy to the full driving a very fine car engineered to the highest of quality and precision.

Chris.

[tim hunter]

Hello again.

 So, this afternoon I borrowed a Snap-on OBD tool, and now see 

..

I was also able to take the car down the road and watch graphs of the signals from the wheel sensors in real time

..so clearly the brand new front left is not working at all, and the rear left looks a bit dodgy too.

I now have the front wheel off and the ABS look disconnected - it all looks absolutely fine and the connector was in firmly.

With the ignition on I get 2.3V at the connector coming from the car. The resistance on the sensor is 1.5 ( on the 20k Scale) - which is exactly the same as the old right front sensor I still have in the workshop.

Other than blindly installing another new front, and a new rear, not entirely sure where to go next.

[Mihanicos]

From the codes you get, the most likely cause is a momentarily open circuit in the sensor circuit in question. Check that there is continuity in the faulty sensor's circuit from the sensor to the skid ecu. Check the harness, sometimes the insulation of the wires is good but the conductors within are cut open . Check the connectors for clean contacts and firm fit.

Another possible cause is the reluctance ring in question, make sure the surface facing the sensor is smooth, free of dirt and oil and that it seats squarely on its seat. Remove any debris and rust filings from there.

Another possibility is the skid control ecu. Check all connectors thereto are clean and firm. Check their contacts are free of corrosion and dirt.

Chris.

[tim hunter]

Thanks for the reply. I have no idea where the skid ECU is mounted, or what it looks like. Are there any illustrations or instructions anywhere?

I will check the electrical connections, though the fact I have voltage at the connector for the ABS sensor would suggest that the harness is ok?

[Mihanicos]

A google search I just did has a few detailed answers for its location and how to access it. There are also quite a few suggestions how to troubleshoot problems related to it.

The abs sensor terminals on the skid ecu should marked according to their location, FR ( front right ), RR ( rear right ). By disconnecting each abs circuit one at a time you can do a continuity test for each circuit. Try to find the harness through which they run. Check for any damage caused over time. There should be some connectors along the route. Make sure you discnnect and reconnect them. It is very common to develop contact resistance due to oxidation, humiditidy thus causing problems.

Compare all the readings you get from all abs sensors so you can decide how to proceed to find the fault. As you take measurements, move the relevant cables and watch for any sudden changes. Make sure you cure the cause.  

You have a very nice car which reflects your taste for fine cars built to the highest quality and precision. It is worth all the time and effort to keep it in perfect running order. I nearly bought one, the only reason I opted out for the GS was the back seats, no room even for children to sit.

Chris.

[tim hunter]

Thanks again for your continued interest

This is now FIXED!

The more I thought it through, the less likely it felt to be an ECU/wiring failure - the car worked fine when it was parked in September, and the only thing that had changed since then was the front ABS sensors.

I took another good look, and the problem was immediately apparent:

 

The new sensor had not seated down properly when I nipped up the fastener, and I had - stupidly - not noticed at the time.

In fact there was a big ridge of corrosion at the top of the bore in the mount that was stopping the o-ring compressing into place.

Always check the obvious mechanical stuff first!

I cleaned it all up, did the full zero point reset one more time and took it for a few miles down the lane. All lights have stayed out, at last.

Tim

[Mihanicos]

I am very happy to read the good news ! Happy motoring!

Unfortunately I always go for the most complicated case and overlook the obvious!

Chris.

[GOLDENGIRL]

hello 

I too have had this nightmare and sadly cant get through MOT with VSC light on.   I am looking to replace the brake servo but struggling to get a part for my 2006 model.  There are Mk 1 parts for the 2002 / 2003 model available at lexusbreakers.co.uk

 

hope this helps

 

I am intrigued at what you say about paperclip ...... tell me more 

[tim hunter]

The procedure is pretty well documented on the web, with several clips on youtube, of somewhat varying quality. Here is the actual procedure, taken from the Lexus manuals. It looks daunting, but is actually straightforward and can be done in a couple of minutes. I use two paper clips, one in each of these pins:

..and just touch them together when needed..

Performing Zero Point Calibration WITHOUT using Diagnostic Computer
1. If the vehicle is equipped with A/T, ensure that the shift lever is in the "P" range and the parking brake is applied. If the vehicle is equipped with a M/T, ensure that the parking brake is applied.
2. Turn the ignition switch ON.
3. Using a paper clip or auto wire, repeat a cycle of short and open between terminals Ts and CG (Pin 12 and pin 4) of DLC3,(16 pin Data Link Connector located under the steering wheel side) 5times within 8 seconds.
4. Verify that the VSC indicator light is lit indicating the recorded zero point is erased.
5. Turn the ignition switch OFF.
6. Be sure the terminals Ts and CG of DLC3 are disconnected.
7. Turn the ignition switch ON.
8. Check that the VSC warning light goes off about 15 seconds after the ignition switch is turned ON.
9. After ensuring that the VSC warning light remains OFF for 2 seconds, turn the ignition switch OFF.
10. Connect terminals Ts and CG of DLC3 using paper clip or auto wire.
11. Turn the ignition switch ON.
12. After turning the ignition switch ON, check that the VSC warning light is lit for about 4 seconds and then starts quick blinking at 0.13 second intervals.
13. After ensuring the blinking of the VSC warning light for 2 seconds, turn the ignition switch OFF.
14. Remove the clip from terminals Ts and CG of DLC3.
15. Drive the vehicle for at least 5 minutes to confirm Zero Point Calibration is complete.

 

That will put all your dash lights out - but they may return as soon as you drive the car, unless you fix the underlying problem.  In my case it was the badly fitted front sensor - and I also need to replace both rear relector rings. The sensors were covered in shavings. This is also well documented if you do a search.

Good luck.

Tim