Fuel Injectors (Using Lab Scope)
NOTE:
For fuel injector circuit testing, see DTCs P0201-P0206: INJECTORS NO. 1-6 CIRCUIT MALFUNCTION under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article. Manufacturer recommends connecting Test Connector (MB991348 and MB998464) to fuel injector during testing procedure.
- Connect lab scope pick-up at fuel injector connector (right bank), intermediate connector (left bank) or Engine Control Module/Powertrain Control Module (ECM/PCM) connector. If connecting lab scope pick-up for right bank injectors (cylinders No. 2, 4 and 6), connect pick-up lead to fuel injector connector terminal No. 2 by backprobing. See FUEL INJECTOR TERMINAL IDENTIFICATION
table.
- If connecting lab scope pick-up for left bank injectors (cylinders No. 1, 3 and 5), connect pick-up lead to fuel injector intermediate connector terminal No. 2 (Yellow/Blue wire, cylinder No. 1), No. 3 (Yellow/Black wire, cylinder No. 3) or No. 4 (Green/Red wire, cylinder No. 5) by backprobing. See Figure
. Intermediate connector is located at left rear of engine, below intake manifold plenum.
- If connecting lab scope pick-up at ECM (M/T), connect pick-up lead to corresponding fuel injector ECM/PCM connector 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. |
Terminal No. |
Wire Color |
| 1 |
1 |
Yellow/Blue |
| 2 |
9 |
Yellow/Red |
| 3 |
24 |
Yellow/Black |
| 4 |
2 |
Green/Yellow |
| 5 |
10 |
Red/Blue |
| 6 |
25 |
Light Green |
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.