Diagnostic Aids

When making measurements on a wiring harness, both a visual inspection and a continuity test should be performed. Inspect terminal connector pins for damage and corrosion, when directed to remove a connector.

Spark timing adjustments are not possible. Timing is controlled by the EDIS module with input from the ECA.
When checking voltage drop to GROUND, circuit must have a voltage drop of less than one volt.
Battery voltage (VBAT) is any voltage reading within 2 volts of actual battery voltage.
Spark timing will vary at idle due to feedback spark strategy used to control idle speed.
DO NOT connect positive lead of EDIS diagnostic cable to battery or connect cable to VR sensor until directed to.
SAW and IDM signal detectors in EDIS diagnostic cable will not work unless diagnostic cable battery leads are connected to battery.
When using DVOM to measure DC voltage always connect positive lead to BOB terminal A(+) and negative lead to A(-).

CAUTION: DO NOT use a 12-volt incandescent (high voltage) test light to test circuit signals, as it will load the circuit and may cause incorrect measurements or faulty EDIS/ECA operations (engine stall).

NOTE: When using PINPOINT TEST procedures for the 4.0L EDIS (Aerostar & Ranger) system, see Fig 1 & Fig 2 .

Fig 1: EDIS Ignition System Wiring Diagram (4.0L Engine)

Courtesy of FORD MOTOR CO.

Fig 2: EDIS Diagnostic Cable Diagram (4.0L Engine)

Courtesy of FORD MOTOR CO.

4.0L EDIS PINPOINT TEST INDEX

Result		Pinpoint Test & Step
No Start
No Codes		A1
Continuous Memory Code 14 (PIP Signal At ECA fault)		A1
KOEO Code 16 (IDM, GND and IGN GND at EAC fault)		A1
KOER Code 18 (EAC/EDIS fault)		A1
"CHECK ENGINE" Light Stays On During Engine Cranking		A1
Engine Runs
Continuous Memory Code 18 (IDM To ECA Circuit Fault)		B1
Continuous Memory Code 45 (Coil Fault)		D1
Lack Of Power Or Poor Fuel Economy		C1

DO NOT connect ECA to EDIS diagnostic cable. The 60-pin connector on this harness may be connected to a Breakout Box (BOB) only. If ECA is connected to EDIS diagnostic cable it may be damaged. Some tests may require a second BOB (ECA BOB) to be connected to ECA 60-pin connector. When a second BOB is used, ECA should be disconnected at all times. Never connect ECA to BOB when performing EDIS diagnostics.

DO NOT bring a fluorescent trouble light (drop light) close to vehicle ignition system wiring. If key is on and VR sensor is disconnected, light may cause EDIS module to fire ignition coil.