My CEL comes on after I drive a few seconds in the morning and if I stop and turn the engine off to check the diagnostic code I cannot because by turning the ignition off it resets and the light no longer comes on.....drive again a few more seconds and its back on. This only happens for a little while, and after driving a few miles I can turn off the engine and the light will not come back on and is OK the rest if the day...... the next morning, same thing starts all over ..... any ideas on what it might be?


90' 4runner 3.0 v6 4wd

 

Just wanted to add 1 more thing........ the light never comes on when the engine is started or when just idling..... it only comes on when it is being driven.


90' 4runner 3.0 v6 4wd

 

This will be interesting to hear what response you get. My CEL comes on also when accelerating. The difference is, mine comes on whenever you accelerate, not simply the first time in the day.


Very odd.

 

You can check the code even with the light off, in fact that is the normal case: http://www.off-road.com/toyota/tech/codes/index.html

 

Thanks 4Crawler, but as soon as the engine is shut off it seems the computer "forgets" why the CEL light was on and no code is stored so nothing shows up doing the diagnostic check......


90' 4runner 3.0 v6 4wd

 

OK, that was not clear in your original post. Maybe the backup power to the ECU is intermittent and it really is forgetting the code.