Circuit Description
The PCM will enable an injector on the intake stroke of each cylinder. Individual cylinder fuel control is referred to as Sequential Multiport Fuel Injection (SFI).
Ignition voltage is supplied directly to the fuel injectors. The PCM
controls each injector by grounding the control circuit via an internal switch
called a driver. The primary function of the driver is to supply the ground
for the component being controlled. Each driver has a fault line which is
monitored by the PCM. When the PCM is commanding a component ON, the voltage
of the control circuit should be (refer to
Injectors
for schematic) low (near 0 volts). When the
PCM is commanding the control circuit to a component OFF, the voltage potential
of the circuit should be high (near battery voltage). If the fault detection
circuit senses a voltage other than what is expected, the fault line status
will change causing the DTC to set.
The PCM will monitor each injector circuit for the following:
| • | A grounded circuit. |
| • | An open circuit. |
| • | A circuit shorted to voltage. |
| • | An injector that is open. |
| • | An injector that is shorted or has low resistance. |
When the PCM detects any of the above malfunctions, a DTC P0200/P1222 will set and the driver will be disabled.
Conditions for Setting the DTC
| • | Engine operating. |
| • | Ignition voltage greater than 10.0 volts. |
| • | The PCM detects the wrong voltage potential on any injector driver circuits for 4.0 seconds or more. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the Malfunction Indicator Lamp (MIL) when the diagnostic runs and fails. |
| • | The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and/or Failure Records. |
| • | The injector will be disabled for the entire ignition cycle. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail. |
| • | A last test failed (Current DTC) will clear when the ignition is cycled and the diagnostic runs and does not fail. |
| • | A History DTC will clear after forty consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | PCM battery voltage is interrupted. |
| • | Using a Scan tool. |
Diagnostic Aids
| • | If an injector is disconnected while the engine is operating and a DTC P0200 sets, the injector driver will be disabled for the entire ignition cycle. |
| • | When the injector driver is disabled, an engine misfire will be apparent and a misfire DTC will set. |
For intermittents, refer to Symptoms .
Test Description
Number(s) below refer to step numbers on the diagnostic table.
-
Determines if a malfunction is present. For any test that requires probing the PCM or a component harness connector, must use the Connector Test Adapter Kit J 35616-A. Using this kit will prevent damage to the harness connector terminals.
-
There are two ways to isolate a malfunctioning injector circuit:
-
Check injector connections before replacing the injector. A faulty connection will cause a DTC P0200 to set.
-
Checks for an ignition feed circuit that is shorted to ground.
| • | DTC P0300 indicates a misfire is present. So if an injector DTC is present at the same time a misfire DTC is set, use misfire event counters to locate the cylinder that is misfiring. |
| • | If no misfire DTC is present, Start and idle the engine while monitoring misfire event counters. If a misfire is present, the misfire event counters will increase for a cylinder that has a misfire. |
Disconnecting the PCM will allow using the DVM (J 39200) to check continuity of the circuits. This will aid in locating an open or shorted circuit.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
Are any of the Misfire Cur. Counters incrementing? | -- | |||
Using a scan tool, monitor the Misfire Hist. Counters on the Misfire Data List (There are a total of 8 counters. One counter per cylinder.) Do any of the Misfire Hist. Counters indicate a number other than 0.0 counts? | -- | Go to Diagnostic Aids | ||
4 |
Important: This step is only for B, D and Y cars. Proceed to step 5 If the vehicle is not a B, D or Y car. Are the injector fuses OK? | -- | ||
5 |
Does the test light illuminate? | -- | ||
Does the test light blink? | -- | |||
7 |
Did the terminal need replacing? | -- | ||
8 |
Does the test light illuminate? | -- | ||
Using a DVM (J 39200), measure resistance of each injector that is powered by the fuse that was open. Does any injector measure less than the specified value? | 11.6 ohms | |||
10 | Repair the injector ignition feed circuit to isolated injector. Refer to Repair Procedures in Electrical Diagnosis (8A Cell 5). Is the action complete? | -- | -- | |
11 |
Is the injector driver circuit open? | -- | ||
12 | Repair injector driver circuit for an open. Refer to Repair Procedures in Electrical Diagnosis (8A Cell 5). Is the action complete? | -- | -- | |
13 | Repair the grounded ignition feed circuit to the injectors. Refer to Repair Procedures in Electrical Diagnosis (8A Cell 5). Is the action complete? | -- | -- | |
14 | Repair intermittent short to ground in the injector ignition feed circuit. Refer to Repair Procedures in Electrical Diagnosis (8A Cell 5). Is the action complete? | -- | -- | |
15 | Replace the faulty injector(s) that was isolated. Refer to Fuel Injector Replacement . Is the action complete? | -- | -- | |
16 |
Important:: Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | -- | |
17 |
Does the scan tool indicate that this test ran and passed? | -- | ||
18 | Using the scan tool, select Capture Info, Review Info. Are any DTCs displayed that have not been diagnosed? | -- | Go to the applicable DTC table | System OK |
