*Automotive Rant* - and blogspot is messing with my paragraph formatting... great!
This little light is a vast irritation. Sunday it came on, then went off. Came on again. Went off again.
So I get out my trusty diagnostics tool (thankfully on the older Toyota's all you needed was a paperclip) and discern the trouble code by reading the morse code of flashing dash lights... Code 71!
Go to the greatness that is the Internet and look up the code to find that it is my EGR system. So I unplug and replug the connector to the EGR system, I notice that there is some bare wire showing (filing this information as a possibility of the problem). I disconnect the neg. battery cable for a few minutes to clear the code, and then fire up the truck. HEY the light is gone! Hooray!
Two days later it turns back on.... So now the list of things running through my head are: tank of bad gas (the whole things started a few hours after filling up), bad temperature sensor wire (as observed earlier), EGR valve stuck open, or bad ECU.
For now I have disabled the EGR valve (by simply blocking off some vacuum tubes with screws), which has definitely increased the performance of the truck (leading me to believe that the entire valve is bad). Of course this doesn't make the check engine light go off, since the temperature sensor has nothing to do with the actual operation of the EGR valve.
So if the light continues to stay on after my next fill-up, I will be shoving a resistor into the plug to at least get the light off, and then order the 2 parts necessary to fix the system, at a price of over $200.
Of course, I could leave the system jimmy-rigged with a resistor and plugged hoses, but that may cause a problem with engine temperature in an engine that is already known for having heat-related head gasket issues. Plus it's bad for the environment...
Sometimes I love working on my truck, but this is not one of those times.