Subaru Legacy problem fixed...

Hi all, In the off chance that anybody cares, here is what happened with the Subaru cold start problem that I posted about here a few days back.

After having the repair place attempt to read the fault code with their high tech snap-on scanner and getting nothing and changing the coolant temp sensor, the problem persisted. Still not starting cold, rad fans running, and constant "check engine" light. After pleading here for help, and getting a few good links to Subaru code extracting procedures, I braved the cold yesterday and crawled under the dash to locate the test connectors. According to the procedure, there are 2 wires that you hook together, then turn on the key to get the computer to flash the codes to you. I found and connected them, turned on the key and waited. There was lots of odd relay clicking sounds, for a few seconds, check engine light stayed on, no codes flashed to me, and then the radiator fans shut off! Then the clicking stopped. Feeling bold that something had changed, I turned the key. Engine cranked for a few seconds, fired and purred!! That after a day and a half of sitting out in below freezing weather. Check engine light went out, fans stayed off and the idle dropped as it warmed up. Engine warmed up, rad fans cycled as they should. Back to normal, YEAH!

Feeling a bit reserved, I did not deem it offically fixed until this morning, after a series of cold starts last night and this morning. Every one perfect.

Not sure excatly what happened, but am blaming the temp sensor, and crediting a test-mode-reset of the computer as the final step. That last part is likely BS, but I am not above making stuff up to convince my daughter that I am brilliant (even in the face of evidance to the contrary).

Carl and Michael, thanks again for your responses and ideas. Much appreciated!

AL A.

Reply to
Al A.
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Seems its POSSIBLE your ECU tried to compensate for one or more marginal sensors and was never cleared after the sensors were replaced. I dunno. glad its fixed and hope it stays that way!

Carl

1 Lucky Texan
Reply to
Carl 1 Lucky Texan

I don't have a better explanation, so that's our story and we're sticking to it!

Glad it worked out, and thanks for the feedback. Next time we can claim to be nearer to geniuses, too.

Mike

Reply to
Michael Pardee

Glad you got it figured out

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xblazinlv

It always amazes me what a powerful resource usenet can be, in spite of the sometimes low singal-to-noise ratio. Has only rarely let me down. The amount of collective knowledge and experience is mind boggling if you stop and think about it.

And don't worry guys, I'll back you up on the genuis claim!

-AL A.

Reply to
Al A.

I did not notice your original post, but if you have a bad temp sensor the computer does to adjust for it. As you suspected (not BS), If you replace it, the computer doesn't know about it so you basically have to reset the computer and that's what those two connectors do (or leave the power off).

Glad you got it fixed.

Remco

Reply to
Remco

WOW! So I really AM a genius! Can't wait to tell my daughter. Seriously, thanks for the info. It is nice to know that it was not one of those "voodoo" fixes, I actually did something right. Even if it was sort of by mistake...

I appreciate the follow up.

All the best, AL A.

Reply to
Al A.

It is nice to have a daughter that thinks you are a genius. I remember mine thinking of me as a genius - and remember becoming a total goober around the day she turned 11 :) If that hasn't happened to you yet, brace yourself!! :)

Remco

Reply to
Remco

This is kinda late, but I'll chime in here anyway.

There _is_ another possible source for your problem, one that you may want to investigate if the issue returns, or if you ever experience similar problems on another vehicle. What sometimes will happen, is that when the wiring harness connectors are assembled, one of the mating pins will not be inserted all of the way into the plastic connector block. These pins typically have some sort of spring/retainer that locks them into the block, but if they are not fully inserted, it will not engage. Then when the connectors are mated, the bad pin is free to slide back away from it's mate. Sometimes this is evident right away, and it is fixed before the car leaves the factory, sometimes it waits for years before causing problems, sometimes it plagues the car/car owner with annoying intermittent problems forever.

If something like this were happening with your car, you may well have fixed it (at least temporarily) while you were wiggling the harness around messing with those diagnostic connectors.

Sometimes you can find an offending connector/wiring pin by systematically flexing the wiring where it enters the connector while the engine is running (it'll stall), More often you will need to disconnect, and carefully inspect all of the connectors. Look for a pin that is sitting at a different height from the rest, or try pulling the wires one at a time to see if you can move one of the pins.

Don't ask me how I know this sad story, but it's true nevertheless. Tell 'em you heard it on alt.autos.subaru . . . ;-)

ByeBye! S. Steve Jernigan KG0MB Laboratory Manager Microelectronics Research University of Colorado (719) 262-3101

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S

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