check engine light VS. clock?

gandcrepaircenter · 04-16-2009, 08:31 PM

Hey gang,
My wife's 98 4runner had a check engine light on, before she could bring to my shop, the light went out. She noted that the clock was blank, then came back. Now the clock has quit again but the check engine light is not on. Are these related???

Thanks, Robert

jdmccright · 04-17-2009, 10:55 AM

The two events should not be related. The clock has nothing to do with the engine's operation, sensors, or emissions. It only serves as a constant reminder that you're late for something. The clock in my Cam will fade in & out as well, so it may be a simple wiring issue.

The check engine light usually lights up immediately when a problem is detected but can also be lit on some systems based on what's called "two-trip detection logic", meaning that if the same issue is detected during two successive engine starts/operations, the code will be stored and the CEL will light up. When the problem being detected is no longer present or doesn't meet the two-trip detection requirement, the light will go out but the code may still be stored in the computer memory. Many auto parts stores will read your codes for free using a code scanner...check it out for any stored codes and have them cleared from memory.

The most likely reason for the CEL coming on is a missing, loose or faulty gas cap. But also check your gauges for any out-of-normal readings, especially oil pressure, engine temperature, and voltage...not necessarily in the RED, but a reading that isn't where it usually should be. That is a sign of some larger impending problem. Have the wife keep a closer eye on the gauges to see if anything creeps up. Hope this helps!