It's because the button. The 275-1556 is a momentary push button which is better for this application. With the button you have, you need to push it on for 3-4 sec and then push it back off to start reading the codes.

I mean, you need to close the circuit for 3-4 sec to ask the module for codes but the circuit needs to open back to start reading the codes.

If you hold the circuit closed for 10 seconds, you delete the first code.

Try pressing the button for 4 seconds and the pressing again to open the circuit and start reading.

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Juan
1995 E320 Sedan
2008 Ford Escape
RC Helicopter