Trac And Engine Light On - Error Code 51 ?

[AppleJack]

I've got a 92 SC400 with the trac light on and check engine light on. Doing the wire jump on the diagnostics I get a error code 51. From what I can read this indicates a switch condition signal. Note: I've noticed rough cold starts if the car sits for 48 hours.

1. Does anyone know what switch condition signal means?

2. How to trouble shoot the cause any further?

3. Is there any harm in driving for several days with the trac and engine light on?

pleeeaaase help,

:cries:

and thanks in advance!

[AppleJack]

Good morning, Help - C'mon - Any takers on this error code 51??

I've tried clearing this alarm by disconnecting the battery and/or fuse ... but still have the trac and engine light come on after a few minutes of driving. I'm putting badly needed new tires on tomorrow and we'll see what happens then. Is there any point to do a brake line and transmission fluid flush ...?

I'm dreading going to the dealer - and you all know why - $$$$

[AppleJack]

Ok - here's the status. New rear tires - and still have problem. Although now I notice it's the check engine light that comes on first and then the trac light follows...

Also, after resetting today, it was gone and then while going down the highway I put the A/C on - and instantly the check engine and trac light came on ... Anybody have ideas how to trouble shoot this (error code 51)?

[lexus082]

Well according to that code it stands for Code 51-- "Switch Signal" I'm not sure what that is exactly. You may be able to call a mechanic and ask them if nobody responds with more detailed info about what a bad "Switch Signal" is. Sorry I can't be of any further help.

[backyard_famer]

I have a similar problem on my '01 ES300 with 125k miles.

Just came on tonight. Check Engine and Trac Off lights. Did you ever get a respone on the error code 51?

Did you go to the dealer?

Thanks,

backyard_farmer

[AppleJack]

Nope - not really. I've been meaning to take it in to the dealer - perhaps in the next day or so .... I got a feeling it's going to be a bit of a cluster whereby they poke and check for some goofy signal and end up with 2 hours labour and who knows what component (or loose wire?) they come up with ...

Gee - can you sense my sarcasm and cynicism ...

Will share if I get good feedback.

[TSP-MIKE]

One of your throttle position sensors are bad. There is one for the Traction Control, and one for the throttle. It's probably the one for the throttle. If you have someone with the same car, switcht them out and see if the problem goes away. If you don't have any one to switch out, i will try to tell you how to check it with a voltmeter.

Mike

[AppleJack]

That sounds probable. It was actually the traction light that originally came on - and then minutes later the engine light.... But after a week or so - they both came on together after getting reset each time ....

Quick question - I'm pretty hands on - is it fairly straightforward to remove and reposition the new sensor into place... ?????

thanks,

[TSP-MIKE]

Should be 2 screws for each sensor, unscrew pull out the sensor and screw the new one in. I don't think it's adjustable.

Mike

[AppleJack]

Well, got the results from the lexus dealer - and get this ... apparently the error code 51 which I obtained form the "wire jump system" didn't register for them.

Instead they found 3 new error codes - #24 (air intake temp sensor signal), 28 (no.2 oxygen sensor signal), and 31 (vacuum sensor signal). YIKES - signal issues! and probably related to one another. Now I've got some homework to do because I know there is lots of info on these already on the network and I can see the dealer running this up to $1000 in no time. Anyone who knows of these are welcome to share their thoughts.

thanks

[AppleJack]

Well, I cleaned the MAF (wasn't very dirty - just a bit dusty),,, and now code 24 and 31 are gone (fingers crossed).

Now I'm left with only code 28 - main O2 sensor signal. I get very consistent results here when it comes on.

Basically, after 5-10 minutes of driving it comes on... and then after shutting down and re-starting check engine light it will beon if still warm, but if more time is allowed for cooling (20 - 30 mins) then it will start without the check engine light on (but code still in ECU of course). Curious if this implies anything such as faulty wiring or ground, ... rather than the sensor ? before I spend the money on the sensors ...

Also, I looked and looked, and looked somemore - is there a tutorial somewhere on how to change the O2 sensors?

[AppleJack]

Still only throwing code 28 (passenger side O2 sensor). Dealer wants $300 for sensor and $200 for install. I'd rather get Denso or Bosch myself for less and install ... but not sure where wire and harness go through floor. Do I need to rip up the passenger carpet and will I have access to the connection? I'd feel better with some words of advise before I venture into this ...

thank you,