code 36, air switch solenoid circuit

the fuel economy on my '93, 4.0, manual, 210k has "tanked". i've got a check engine light. codes, (checked twice)

12- battery disco
36- air switch solenoid circuit, i cannot find any reference in haynes, fsm, 'net, 1 reference here, something regarding a second o2. my '93 has just one, if memory serves(it's raining, i'm a bit reluctant to crawl under it right now).
33-ac clutch, i've put it on a switch
35-cooling fan relay, switched as well
22-coolant sensor or circuit, i assume it is in refernce to the front sensor, which a) is run to an aftermarket gauge, no longer the computer. and b) which i believe is not involved in engine management, the rear one handles that.

any ideas?

I don't know if you have sorted this out by now but the rear temp sensor is for the gauge. The front sensor is involved with engine management and should go to the ECU/computer.

You have only one O2 sensor.

i have, thanks for the response.