Fuel Injectors (Using Lab Scope)

NOTE: For fuel injector circuit testing, see DTCS P0201, P0203 & P0205: INJECTOR CIRCUIT MALFUNCTION (CYLINDERS NO. 1, 3 & 5) or DTCS P0202, P0204 & P0206: INJECTOR CIRCUIT MALFUNCTION (CYLINDERS NO. 2, 4 & 6) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - SEBRING COUPE & STRATUS COUPE - 3.0L article. Manufacturer recommends connecting Test Connector (MB991709) to fuel injector during testing procedure.

Connect lab scope pick-up at fuel injector connector or Engine Control Module/Powertrain Control Module (ECM/PCM) connector. If connecting lab scope pick-up at left bank injector (No. 2, 4 or 6) connector, connect pick-up lead to fuel injector connector terminal No. 2 by backprobing. If connecting lab scope pick-up at right bank fuel injector (No. 1, 3 or 5) connector, connect Test Connector (MB991348) between intermediate 4-pin harness connector B-118 halves. Connect pick-up lead to test connector terminal No. 2 (Black lead) for injector No. 1. Connect pick-up lead to test connector terminal No. 3 (Blue lead) for injector No. 3. Connect pick-up lead to test connector terminal No. 4 (White lead) for injector No. 5.
If connecting lab scope pick-up at ECM connector C-111 (M/T) or PCM connector C-112 (A/T), connect pick-up lead to corresponding fuel injector ECM/PCM terminal by backprobing. See FUEL INJECTOR TERMINAL IDENTIFICATION table.
Start engine and let engine idle. Compare waveform to normal pattern. See Fig 1 . Waveform should be stable with engine idling. If point "A" is extremely small or does not appear, fuel injector solenoid is shorted. Point "B" should extend when engine RPM is suddenly increased. After RPM steadies, point "B" will return to normal. If point "B" is erratic, problems with the ECM/PCM exist.

FUEL INJECTOR TERMINAL IDENTIFICATION

Cylinder No. ⁽¹⁾

ECM/PCM Connector Terminal No. ⁽²⁾

Wire Color

Yellow/Blue

Yellow/Red

Yellow/Black

Green/Yellow

Red/Black

Light Green

⁽¹⁾	All described circuits service fuel injector terminal No. 2. Fuel injector terminal No. 1 is a Red wire for all injectors.

⁽²⁾	ECM connector C-111 (M/T) or PCM connector C-112 (A/T). See Figure or Figure .

Fig 1: Identifying Normal Injector Waveform

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.