P1628

P1628-SENSOR REFERENCE VOLTAGE CIRCUIT ERRATIC





For a complete wiring diagram refer to Diagrams/Electrical.

- When Monitored:

With the ignition on.

- Set Condition:

The PCM detects an excessive voltage variation on the 5 volt supply circuit.






Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test

1. DTC IS ACTIVE

Start the engine and allow it to reach normal operating temperature.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

- Go to 2

No

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. Checking for an Intermittent DTC

2. (K858) 5 VOLT SUPPLY CIRCUIT VOLTAGE





Turn the ignition off.

Disconnect the APP Sensor harness connector.

Turn the ignition on.

Measure the voltage of the (K858) 5 Volt Supply circuit in the APP Sensor harness connector.

Select the appropriate response from the list below:

Voltage above 5.2 volts

- Repair the (K858) 5 Volt Supply circuit for a short to voltage.
- Perform the PCM Verification Test Ver. 1. PCM Verification Test

Voltage between 4.8 and 5.2 volts

- Go to 3

Voltage below 4.8 volts

- Go to 4

3. ACCELERATOR PEDAL POSITION SENSOR





Turn the ignition off.

Connect the APP Sensor harness connector.

Disconnect the Camshaft 1/1 Position Sensor harness connector.

Turn the ignition on.

Measure the voltage of the (K857) 5 Volt Supply circuit in the Camshaft 1/1 Position Sensor harness connector.

Is the voltage below 4.8 volts?

Yes

- Replace the Accelerator Pedal Position Sensor.
- Perform the PCM Verification Test Ver. 1. PCM Verification Test

No

- Go to 9

4. CAMSHAFT 1/1 POSITION SENSOR





Turn the ignition off.

Disconnect the Camshaft 1/1 Position Sensor harness connector.

Turn the ignition on.

Measure the voltage of the (K858) 5 Volt Supply circuit in the APP Sensor harness connector.

Is the voltage above 4.8 volts?

Yes

- Replace the Camshaft 1/1 Position Sensor.
- Perform the PCM Verification Test Ver. 1. PCM Verification Test

No

- Go to 5

5. MAP SENSOR





Turn the ignition off.

Disconnect the MAP Sensor harness connector.

Turn the ignition on.

Measure the voltage of the (K858) 5 Volt Supply circuit.

Is the voltage above 4.8 volts?

Yes

- Replace the MAP Sensor.
- Perform the PCM Verification Test Ver. 1. PCM Verification Test

No

- Go to 6

6. MANIFOLD FLOW VALVE





Turn the ignition off.

Disconnect the Manifold Flow Valve harness connector.

Turn the ignition on.

Measure the voltage of the (K857) 5 Volt Supply circuit.

Is the voltage above 4.8 volts?

Yes

- Replace the Manifold Flow Valve.
- Perform the PCM Verification Test Ver. 1. PCM Verification Test

No

- Go to 7

7. 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND





NOTE: All sensors connected to the (K857) 5 volt supply circuit and the (K858) 5 volt supply circuit must be disconnected.

Turn the ignition off.

Disconnect the PCM harness connectors.

Measure the resistance between ground and the (K857) 5 Volt Supply circuit.

Measure the resistance between ground and the (K858) 5 Volt Supply circuit.

Is the resistance above 1000 ohms for both circuits?

Yes

- Go to 8

No

- Repair the 5 Volt Supply circuit for a short to ground.
- Perform the PCM Verification Test Ver. 1. PCM Verification Test

8. 5-VOLT SUPPLY CIRCUIT OPEN OR HIGH RESISTANCE

NOTE: All sensors connected to the (K857) 5 volt supply circuit and the (K858) 5 volt supply circuit must be disconnected.

Turn the ignition off.

Measure the resistance of the (K857) 5 Volt Supply circuit between the Camshaft 1/1 Position Sensor harness connector and the PCM harness connector.

Measure the resistance of the (K857) 5 Volt Supply circuit between the MAP Sensor harness connector and the PCM harness connector.

Measure the resistance of the (K857) 5 Volt Supply circuit between the Manifold Flow Valve harness connector and the PCM harness connector.

Measure the resistance of the (K858) 5 Volt Supply circuit between the Accelerator Pedal Position Sensor harness connector and the PCM harness connector.

Is the resistance below 5.0 ohms for all of the circuits?

Yes

- Go to 9

No

- Repair the 5 Volt Supply circuit for an open circuit or high resistance.
- Perform the PCM Verification Test Ver. 1. PCM Verification Test

9. POWERTRAIN CONTROL MODULE (PCM)

Inspect the (K857) 5 Volt Supply circuit between the Camshaft 1/1 Position Sensor harness connector and the PCM harness connector.

Inspect the (K857) 5 Volt Supply circuit between the MAP Sensor harness connector and the PCM harness connector.

Inspect the (K857) 5 Volt Supply circuit between the Manifold Flow Valve harness connector and the PCM harness connector.

Inspect the (K858) 5 Volt Supply circuit between the Accelerator Pedal Position Sensor harness connector and the PCM harness connector.

Inspect all PCM power and ground circuits.

Look for any chafed, pierced, pinched, or partially broken wires.

Look for broken, bent, pushed out or corroded terminals.

Refer to any Technical Service Bulletins that may apply.

Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test Ver. 1. PCM Verification Test

No

- Replace the PCM.
- Perform the PCM Verification Test Ver. 1. PCM Verification Test