940 Non-turbo

I have this erratic idling, which I've tried all stuff to remedy. Having checked vacuum leak and everything else I thought I check the AMM though I changed that just a couple years back. I unplugged the AMM connector just to see if the car drives better but it rocked constantly meaning that the AMM should by ok.

Now here is the problem. When I try to reset the ECU since the lambda light came on with the removal of the AMM connector, I just could not reset it. For some reasons, when I press the diagnostic unit button (with flyhead in socket 2) once for 5,6,6,7,8,9, or 10 seconds the red light did not come on the second time for the clearance of the fault code. While continuing with my attempt I had to attend to the phone and when I came back, I had to back out because my other car had to leave the garage so I started the engine absolutely forgotton that the flyhead of the Diagnostic unit was still at the no. 2 socket. To make it short, I could not clear the fault code thereafter. Now the fault code continue to read 1-2-1 and the lambda light continue to come on.

Did I or did I not damage the ECU? This is a real expensive item and I really don't know how I'm ever going to get this fix if it is damaged. Already the high fuel consumption has increased my monthly cost. (17mpg).

Laozong

Disconnecting ANY electrical component of the FI or ignition systems is a no-no while the key is on: high risk!. Turn off the ignition. Re-connect everything you disconnected. Disconnect the battery. Leave it for several minutes. Reconnect. Run the error codes again. You should have cleared it.

Thank you for the information. I'll most certainly remember these points when I disconnect anything in the future.

BTW, can a hardened dipstick O-ring cause idle fluctuation?

Thanks.

Laozong

Thanks Steve Once Again.

I only disconnect the AMM because I've read in this Board that the only way to test whether the AMM is good is to disconnect it and see if driveability improves.
I'm at work now and the first thing I get back this evening, I'll disconnet the battery and see if everything turns out all right. Hope nothing is damaged.

Thanks again.

Laozong

Disconnecting and reconnecting your AMM is OK, but only while the ignition is off. Same is true for the battery. Otherwise large surges destroy the circuits.