1992 400E California Smog Check and Check Engine Light (CEL) On

[parnelltk]

I have a 1992 400E with 184K Miles on it. The car runs well and starts easily. I need a California Smog Check and have to use a Test Only Station.
The Check Engine Light (CEL) is On Continously (has been for quite a while) and the Smog Check shop says the Check Engine Light (CEL) On will definitely cause the car to fail the Smog Check.

1: How to reset the Check Engine Light (CEL) on the 1992 400E? I was told that disconnecting the battery for a minute or so will reset the light, but no success thus far.

2. Will the Check Engine Light ON cause the car to fail California Smog? This car is always near the limits on the Smog Test. Warming it up thoroughly with some high-speed driving etc. really helps.

3: Does the 1992 400E have the Push Button and LED for getting a trouble code output? How does it work? I have read lots of posts and it is unclear to me how it is setup on the 1992 400E.

Thanks,
Kim