Blinking CHECK ENGINE light after reading codes

schspeedster · Post by **schspeedster** » Wed Mar 19, 2008 12:53 am

After connecting connectors under the dash to read codes, the CEL blinks on & off continuously while running & driving. Both connectors are disconnected.

Have tried to reset the ECU by disconnecting negative from battery overnight, starting & idling 15 mins without touching accelerator, then shutting off. Still seems to run OK but CEL blinks contantly.

Codes obtained with black connectors connected:

11 - crank sensor
13 - cam sensor
31 - throttle

http://www.legacycentral.org/library/li ... /codes.htm

Original problem is intermittent cold start problem, usually in 40-50F outside temp range. Cranks for several minutes sounds like its trying to start, weak or no spark. Odor of unburned fuel when it finally starts. Had problem since bought car 3 years ago. Got much worse recently. Changed coolant temp sensor, plugs & wires.

cjc · Post by **cjc** » Wed Mar 19, 2008 4:37 am

have you checked coil pack and igniter?

schspeedster · Post by **schspeedster** » Wed Mar 19, 2008 4:58 pm

Seems to startup and run ok now, would a ignitor or coil failure cause the CEL to blink?

Post by **Legacy777** » Wed Mar 19, 2008 5:57 pm

It shouldn't.

You positive the connectors are disconnected? If so, try pulling the EGI/TCU fuse, pretty sure it's fuse 14.

schspeedster · Post by **schspeedster** » Thu Mar 20, 2008 1:31 am

Besides disconnecting battery and pulling fuse, have connected and disconnected both green and black connectors. With all 4 combinations of green and black open & closed, the engine starts & runs OK with CEL blinking on & off.

Been thru the resets in http://www.surrealmirage.com/subaru/engine.html

At this point the check engine light should start to flash the all clear signal (steady 1/2 second interval flashes). At this point the ECU's memory is cleared

I would assume the all clear signal is supposed to go away on its own?

Does the computer have any non-volatile memory that persists after battery disconnect? Hopefully checking codes doesnt risk permanently damaging the ECU.

Post by **Legacy777** » Thu Mar 20, 2008 5:37 pm

schspeedster wrote:Been thru the resets in http://www.surrealmirage.com/subaru/engine.html
At this point the check engine light should start to flash the all clear signal (steady 1/2 second interval flashes). At this point the ECU's memory is cleared
I would assume the all clear signal is supposed to go away on its own?

You have to disconnect the connectors, but it sounds like you did this....correct?

schspeedster · Post by **schspeedster** » Thu Mar 20, 2008 8:45 pm

Legacy777 wrote:
schspeedster wrote:Been thru the resets in http://www.surrealmirage.com/subaru/engine.html
At this point the check engine light should start to flash the all clear signal (steady 1/2 second interval flashes). At this point the ECU's memory is cleared
I would assume the all clear signal is supposed to go away on its own?
You have to disconnect the connectors, but it sounds like you did this....correct?

Yes, both the green and black connectors are disconnected.

schspeedster · Post by **schspeedster** » Thu Mar 20, 2008 9:01 pm

Used the relearn procedure of starting and idling 10-15 minutes without touching the gas pedal. Havent driven too many miles since. I wonder how many miles of driving or cycles from cold to operating temperature are necessary for the ECU to relearn the settings.

schspeedster · Post by **schspeedster** » Thu Mar 20, 2008 11:20 pm

Went for a half hour drive with full range of speed and throttle position, the CEL flashes continuously. The POWER light that normally goes on at wide open throttle doesnt light.

There has to be another means of resetting the ECU that I have overlooked. Does it require reprogramming with Subaru Select Monitor? Never thought that connecting jumpers to check and clear codes risked permanent damage.

schspeedster · Post by **schspeedster** » Fri Mar 21, 2008 12:01 am

Post by **Legacy777** » Fri Mar 21, 2008 3:30 am

Sounds like something may be funky with your ECU.

vrg3 · Post by **vrg3** » Fri Mar 21, 2008 3:16 pm

The ECU's never supposed to blink the check engine light unless it's in test mode, read mode, or clear mode.

The way these two connectors work is that one end is connected to the ECU and the other end is connected to ground. Is it possible that one end of one of those connectors is touching something else under your dash that's grounded?

schspeedster · Post by **schspeedster** » Sat Mar 22, 2008 3:42 am

vrg3 wrote:The ECU's never supposed to blink the check engine light unless it's in test mode, read mode, or clear mode.

The way these two connectors work is that one end is connected to the ECU and the other end is connected to ground. Is it possible that one end of one of those connectors is touching something else under your dash that's grounded?

Good suggestion. Had to pull on the green connectors to get enough slack to connect them, will have to check for a wire up against a sharp metal edge.

vrg3 · Post by **vrg3** » Sat Mar 22, 2008 6:46 am

Oh. Yeah, if you had to pull hard on them, it seems quite possible that the insulation may have been damaged.

The ends you want to investigate are the read mode connector with the red-with-black-stripe wire and the test mode connector with the orange wire. The other ends have black-with-red-stripe wires and they're the ground side.

schspeedster · Post by **schspeedster** » Wed Mar 26, 2008 6:44 am

Wires: OK
ECU: FAIL
Running good now with the ECU replaced.

schspeedster · Post by **schspeedster** » Thu Mar 27, 2008 7:18 am

Still starts and runs good. Thanks to all for the help!

BTW got a new Legacy 2.5i SE few weeks ago, and am selling the car: http://bbs.legacycentral.org/viewtopic.php?t=35329

vrg3 · Post by **vrg3** » Thu Mar 27, 2008 6:49 pm

Great! I wonder what happened to the ECU though. That's weird. Maybe it got zapped with static electricity or something?

bry · Post by **bry** » Sat Apr 24, 2010 1:43 am

linda's '94 has started flashing the CEL continuously for no reason. runs like a top though....

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Blinking CHECK ENGINE light after reading codes

Blinking CHECK ENGINE light after reading codes

Re: Blinking CHECK ENGINE light after reading codes