Re: strange check engine light

[WEG1192@aol.com]

I did check my soldering. I ohmed every MEMCAL pin back to the particular 
chip pin and checked for cross shorts also. Everything checked good. Field 
service mode is when you jumper ALDL A and B and the SES light flashes the O2 
sensor status to you. Its a neat way to check for good closed loop operation 
in that you can sort of watch your O2 counts. What I don't understand is why 
the jumper gets rid of the problem cause the SES light goes out and the 
engine runs fine until the next crank. My thoughts are that I damaged the 
netres chip with heat and when the ECM checks the netres at startup, it sets 
the code but field service mode somehow overrides the EPROM code. I've driven 
over 500 miles with this chip like this, but I have to have that jumper handy 
every time.     JW
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