My '95 4runner (3litre V6 petrol) is showing a check engine light, but when we pull the codes on the system (with several different models of code scanners) it shows no codes in the system. How can I identify the cause of the light if there are no codes? Any help would be appreciated.

One observation I should add is that if I keep my revs low the light doesn't come on, but once I hit around 3000rpm the light appears.

Thanks

 

kinda sounds like a knock sensor...

have you jumped diagnostic terminals with a paper clip??

 

Spacejunk, thanks for your suggestion. No I haven't tried using a paperclip - I've heard of that but don't know how to do it. Do you know where i can find a thread that explains how to do that?

I would have thought that using an ODBC-II scanner tool would have been more complete than using the paperclip approach as I thought that that was only a backward compatibility approach for the earlier ODBC systems. Might it really show me something different?

 

You don't have ODB2 in your truck. Maybe that's why it won't read. You would have thought it would be backwards compatible though...

To pull codes just short the diagnostic box under the hood the same way the under hood sticker says to do it to set the timing. The CEL light will flash out a code. There should be plenty more information here if you search for it.

 

when you hook up a scanner the light in the dash will blink. count the number of blinks and write them down. A 2 digit number will blink the first number(how many times it blinks on dash) then pause a sec and blink another number. Thats a code. And if you have more than one code it will have a 5sec pause between codes.

 

Thank you all for your guidance. In fact, it would appear that the scanners used by two companies to scan my vehicle are not backward compatible with the ODBC version in my vehicle. By using the paperclip approach I have confirmed a code of 52 - the knock sensor - well guessed space-junk!

again. thanks all for your advice.

 

Yes... props to SJ for an excellent, educated guess.

Now... to fix the problem...

 

Code 52 can be annoyingly persistent. Here's one recent thread on the subject:

https://www.yotatech.com/forums/f116...sensor-184480/

You might also search this forum on "code 52" or "knock sensor".