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Check engine light and no codes

Posted: Thu Dec 20, 2007 3:34 am
by Tim Catton
I have a '94 Legacy wagon w/auto, about 210K on it. Recently the Check Engine light came on and stayed on, cooling fans run all the time, car appears to still be running fine. I hooked up the green plugs under the dash to read the codes as per my Haynes manual and the check engine light just stays on, I can hear solenoids clicking. I disconnect the plug, fire it up, no light, no fans, back to normal. Until the engine gets up to operating temperature and then the light comes back on. Any ideas? Will I hurt anything on this car to drive it like this?
I don't know if it has anything to do with it but just prior to this happening the speed-o-meter started going out on me and I had to disconnect it until I can find a replacement.
I live in a small town in NE Minnesota and the local shop here doesn't have a code reader that will read this car and the closest dealer is about 120 miles.

Posted: Thu Dec 20, 2007 3:48 am
by vrg3
Hooking up the green plugs isn't how you read the codes. Read the stickies in the relevant forums here and you'll learn how to pull the codes.

Nice work giving us all the relevant information, though -- when you pull the codes you will get a code 33, for the vehicle speed sensor. The VSS is built into the speedometer, so with the speedometer disabled the ECU gets no speed signal. I guess it just doesn't care until the car is warmed up because the primary use for the VSS is deciding whether or not to run the cooling fans when the engine is warm; if you're moving fast enough it doesn't bother.

So I wouldn't worry about it. The ECU's failsafe mode for code 33 should be to run the radiator fan whenever coolant temperature is above 200 degrees. So you should be fine until you can fix the speedometer. Keep an eye on your temperature gauge just in case, though, of course.

Posted: Thu Dec 20, 2007 4:42 am
by Tim Catton
Thanks. I read the stickies and scanned through some of the forums. Is there some other way to pull codes other than building a scan tool? I don't have a laptop that I would be able to hook it up to.

What is the green plug for, the one Haynes says to connect and read "check engine" flashes?

Posted: Thu Dec 20, 2007 5:12 am
by vrg3
You need to use the black connectors to read the codes. The green connectors are used for active testing or to clear the codes.

Posted: Thu Dec 20, 2007 5:13 am
by magicmike
go here
http://www.surrealmirage.com/subaru/engine.html
the green connectors are for an advanced code check or something like that. dont use them. use the black ones by your right knee under the dash. connect with the key off and then turn the key to the on possition but dont start the car. then count the flashes.