Circuit Description
The ignition relay, also called the EFI relay, provides ignition positive voltage to the control module and other engine control components anytime the ignition is ON. One side of the coil of the EFI relay is always grounded. The other side of the coil receives 12 volts from the powertrain control module (PCM). When the coil is energized, a magnetic field closes the switch side of the relay, supplying power to the following engine components:
| • | The fuel pump relay, also called the circuit opening relay |
| • | The heated oxygen sensors (HO2S) |
| • | The mass air flow (MAF) sensor |
| • | The evaporative emission (EVAP) control system solenoids |
| • | The idle air control (IAC) valve |
| • | The powertrain control module (PCM) |
Diagnostic Aids
Check for any of the following conditions:
| • | Check the resistance of the EFI relay. There is continuity across terminal 1 and terminal 2. The resistance across terminal 5 and terminal 3 is infinite. |
| • | The EFI relay electrical contacts may be pitted or sticking. Replace the EFI relay if tapping gently on the relay or wiggling the relay causes a change in the relay's operation. |
| • | The performance of the EFI relay may be affected by temperature. Check the EFI relay after sitting outside overnight and after running the engine 30 minutes. |
| • | If the EFI fuse opens during cranking, check for a shorted fuel pump/circuit. The EFI relay supplies current to the circuit opening relay that supplies power the fuel pump. The circuit opening relay is energized during cranking and when reference pulses are detected by the PCM. |
An intermittent malfunction may be caused by a fault in the EFI relay electrical circuit. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions .
Use the following relay cavity table in order to locate the correct cavities to probe during diagnosis. The table layout corresponds to the cavity layout of the relay block.
Relay Cavity Identification | |
|---|---|
Switch Load | |
Switch Power | |
Coil Power | Coil Ground |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
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This step will verify the ground path for the EFI relay circuit.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics | |||
Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | ||
2 | Test for an open in the EFI fuse. Was an open fuse found? | Go to Step 10 | Go to Step 3 |
3 |
Did the EFI relay click when being reinstalled into the fuse block? | Go to Step 4 | Go to Step 5 |
4 |
Does the test lamp illuminate? | Go to Step 11 | Go to Step 7 |
5 | Probe terminal 1 of the EFI relay on the fuse block side using a test lamp connected to ground. Does the test lamp illuminate? | Go to Step 6 | Go to Step 8 |
Does the test lamp illuminate? | Go to Step 12 | Go to Step 9 | |
7 | Repair the open or poor connection in the ignition positive voltage circuit between the EFI fuse and the EFI relay. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 14 | -- |
8 |
Did you find and correct the condition? | Go to Step 14 | Go to Step 13 |
9 | Repair the open in the ground circuit between the EFI relay and G103. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 14 | -- |
10 | Repair the short to ground in the EFI fuse circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 14 | -- |
11 |
Did you find and correct a wiring fault? | Go to Step 14 | Go to Step 12 |
12 | Replace the EFI relay. Did you complete the replacement? | Go to Step 14 | -- |
13 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | Go to Step 14 | -- |
14 | Operate the vehicle within the conditions under which the original concern was noted. Does the system operate properly with no DTCs? | System OK | |
