09-27-2004, 01:23 PM
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Join Date: Jan 2004
Location: Minneapolis, MN, USA
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Issues resolved (1981 Corolla sensor light)
After posting on this forum and alt.autos.toyota (the newsgroup was very helpful), I've got the light out. For the 1981 Corolla there is a small white box (about 1" x 0.75" x 0.5") at the end of blue, yellow, and red wires leading from the main wiring harness by the drivers left foot (US models). I think this normally hooks onto the top of the panel with the speaker grill on it (there's a metal clip on the side of the box), but in my car it had fallen behind this panel making it tough to find (I had to unbolt the panel to get it out). The box has a cap that flips open and reveals a slide switch. Moving this switch to the other setting that it is currently in resets the sensor light for another 30,000 miles.
Note that in this pre-electronic version of the Corolla this is not a "check engine" light. It is an oxgen sensor reminder light that is not connected to the emissions computer at all, but is only connected to the odometer. It is not reporting the actual sensor condition and resetting the light does not exclude having to test the sensor. I finally bought a copy of the 1981 Toyota Corolla service manual (the pricey one put out by Toyota) to find out how to properly test the sensor. There's one or two parts to the vacuum system that need to be temporarily disconnected, then it's a matter of using a tachometer to help run the engine to 2500 rpm and using a voltmeter to test for output from a special test connector up near the brake and manual transmission fluid reservoirs.
I don't know about Chilton's, but the Haynes manual fails on the oxygen sensor. They don't mention it at all in the index, and in reading the manual cover to cover the sparse mention doesn't include any information on how to test the sensor or reset the light (unless you're good at figuring out things from wiring diagrams). This is a disappointing omission since it is within the capability of a person who can do things like change their own sparkplugs, and is is something that is guaranteed to come up every 30,000 miles.[
1981 Corolla Wagon, 5-speed, 159k miles-- my winter wheels
1981 Corolla Wagon, AT, 125k miles-- my summer wheels
** I replaced a horn. Isn't that mod. enough?