Test 34, Check IDM Output From EDIS Module
WARNING: This page does not describe the selected car, but rather 11 other vehicles, including the 1991 Ford Ranger, 1991 Ford RV Cutaway, 1991 Ford Pickup, 1991 Ford F-Super Duty, and 1991 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
With key off and ECA connected, set DVOM to 20-volt scale. Push EDIS IDM button at EDIS diagnostic cable connector to breakout box. Crank engine, and measure voltage between breakout box pins No. J30 (EDIS diagnostic cable IDM detector) and J7 (BAT -). If voltage is 5-7 volts, go to next test. If voltage is not 5-7 volts, replace EDIS module. Remove all test equipment, and reconnect all components. Clear Continuous Memory, and check for fault codes.