Fuel System - Circuit Opening Relay Diagnosis. Geo Prizm 1996

For 1990-2009 cars

Schematic Reference: Refer to Engine Controls Schematics

### Circuit Description

When the ignition switch is turned to the START position, the circuit opening relay will be energized to allow the fuel pump to operate and pressurize the system. The fuel pump will continue to operate if the powertrain control module (PCM) receives an ignition signal when the engine is started The fuel pump operates as long as the circuit opening relay is energized by the PCM. When the circuit opening relay is de-energized, the fuel pump will stop operating.

### Diagnostic Aids

A restricted or leaking fuel feed pipe or hose will cause an Engine Cranks But Will Not Run conditions. Check fuel sender assembly connections inside of the fuel tank for poor connections. Refer to the Fuel Pressure Test.

An intermittent malfunction may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connections before component replacement.

If the engine starts while cranking and then stalls when key is placed in the run position. The fault may be in the Circuit Opening Relay Control circuit or, the PCM may not be providing a ground.

### Test Description

The numbers below refer to the step numbers in the diagnostic table.

1. The OBD System Check 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.

2. If the fuel pump fails to run, then the fault can be isolated to either the circuit opening relay control circuit, circuit opening relay, or fuel pump.

3. This test will verify whether the PCM is grounding the Circuit Opening Relay.

4. This circuit is only activated during cranking. If this circuit is opened the Circuit Opening Relay will still function properly.

5. This circuit is only activated during cranking. If this circuit is opened the Circuit Opening Relay will still function properly.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check

2

1. Turn the ignition switch ON.
2. Using a fused jumper, momentarily backprobe the PCM connector cavity C1-14 to ground.

Important: The fuel pump should run while fused jumper is connected.

3. Listen for the fuel pump to run.

Does the fuel pump run?

--

Go to Step 3

Go to Step 4

3

1. Using a test light connected to battery voltage, backprobe the PCM connector cavity C1-14.
2. Crank the engine and observe the test light.

Does the test light illuminate?

--

Refer to Fuel System Diagnosis

Go to Step 19

4

1. Disconnect the circuit opening relay.
2. Using a DMM, probe connector cavity 3 of the circuit opening relay (harness side).
3. Measure the voltage while cranking the engine.

Does the DMM read within the specified value?

--

Go to Step 5

Go to Step 6

5 | Using a test light connected to battery voltage, probe connector cavity 5. Does the test light illuminate? | -- | Go to Step 8 | Go to Step 7
6 | Repair the open between the circuit opening relay connector cavity 3 and the PNP switch (A/T) or the CPP (M/T). Is the action complete? | -- | Go to Step 20 | --
7 | Repair the open in the circuit opening relay ground circuit. Is the action complete? | -- | Go to Step 20 | --
8 | Connect a fused jumper from connector cavity 1 of the circuit opening relay (harness side) to battery voltage. Does the fuel pump run? | -- | Go to Step 9 | Go to Step 13

9

1. Disconnect the fused jumper.
2. Turn the ignition switch ON.
3. Using a test light connected to ground, probe the connector cavity 2 of the circuit opening relay (harness side).

Does the test light illuminate?

--

Go to Step 10

Go to Step 11

10

1. Turn the ignition switch ON.
2. Using a test light connected to battery voltage, probe connector cavity 4 of the circuit opening relay (harness side).
3. Crank the engine and observe the test light.

Does the test light illuminate while cranking the engine?

--

Go to Step 17

Go to Step 12

11

1. Check for an open or short in the power feed wire between the circuit opening relay connector cavity 2 and the EFI F-HTR relay.
2. Repair as necessary.

Is the action complete?

--

Go to Step 20

--

12

1. Check for an open or short in the circuit opening relay control wire.
2. Repair as necessary.

Was the repair necessary?

--

Go to Step 20

Go to Step 19

13

1. Leave the fused jumper connected to the circuit opening rely terminal 1.
2. Disconnect the fuel sender unit connector.
3. Using a test light connected to ground, probe the fuel sender unit connector cavity 4.

Does the test light illuminate?

--

Go to Step 14

Go to Step 15

14

1. Disconnect the fused jumper.
2. Using a test light connected to voltage, probe the connector cavity 5 of the fuel sender unit (harness side).

Doe the test light illuminate?

--

Go to Step 18

Go to Step 16

15

1. Check for an open or short in the fuel pump power feed wire between the circuit opening relay connector cavity 1 and the fuel sender unit.
2. Repair as necessary.

Is the action complete?

--

Go to Step 20

--

16 | Repair the open in the fuel pump ground between the fuel pump and G300. Is the action complete? | -- | Go to Step 20 | --
17 | Replace the circuit opening relay. Is the action complete? | -- | Go to Step 20 | --
18 | Replace the fuel pump. Is the action complete? | -- | Go to Step 20 | --
19 | Replace the PCM. Refer to Powertrain Control Module Replacement. Is the action complete? | -- | Go to Step 20 | --

20

1. Using a scan tool, cleat the DTCs.
2. Attempt to start the engine.

Does the engine start and continue to run?

--

Go to Step 21

Go to Step 2

21 | Allow the engine to idle until normal operating temperature is reached. Are any DTCs displayed? | -- | Go to the applicable DTC table | System OK