Chrysler 300/300 Touring/300C, Dodge Magnum. Manual — part 1378

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When Monitored:
With the ignition on and the Fuel Pump Relay command off.

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Set Condition:
The ECM does not detect voltage on the (K31) Fuel Pump Relay Control circuit for 2.0 seconds.

Possible Causes

INTERMITTENT DTC

(K31) FUEL PUMP RELAY CONTROL CIRCUIT SHORTED TO GROUND

(K31) FUEL PUMP RELAY CONTROL CIRCUIT OPEN OR HIGH RESISTANCE

(K343) FUSED ASD RELAY OUTPUT 2 CIRCUIT OPEN OR HIGH RESISTANCE

FUEL PUMP RELAY

ENGINE CONTROL MODULE (ECM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)

Diagnostic Test

1.

DTC IS ACTIVE

Ignition on, engine not running.

With the scan tool, Clear DTCs in the Engine Control Module (ECM).

With the scan tool, actuate the Fuel Pump Relay.

Monitor the scan tool for at least two minutes.

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. (Refer to 9 - ENGINE -

DIAGNOSIS AND TESTING)

2.

(K31) FUEL PUMP RELAY CONTROL CIRCUIT SHORTED TO GROUND

Turn the ignition off.

Remove the Fuel Pump Relay.

Disconnect the Engine Control Module (ECM) connector.

Measure the resistance between ground and the (K31) Fuel Pump
Relay Control circuit in the Fuel Pump Relay connector.

Is the resistance above 10.0 ohms?

Yes

>> Go to 3

No

>> Repair the (K31) Fuel Pump Relay Control circuit for a short

to ground.

Perform the ECM Verification Test Ver. 1. (Refer to 9 -
ENGINE - DIAGNOSIS AND TESTING)

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3.

(K31) FUEL PUMP RELAY CONTROL CIRCUIT OPEN OR HIGH RESISTANCE

Measure the resistance of the (K31) Fuel Pump Relay Control circuit
between the Fuel Pump Relay connector and the Engine Control Mod-
ule (ECM) connector.

Is the resistance below 10.0 ohms?

Yes

>> Go to 4

No

>> Repair the (K31) Fuel Pump Relay Control circuit for an

open circuit or high resistance.

Perform the ECM Verification Test Ver. 1. (Refer to 9 -
ENGINE - DIAGNOSIS AND TESTING)

4.

(K343) FUSED ASD RELAY OUTPUT 2 CIRCUIT OPEN OR HIGH RESISTANCE

Connect the Engine Control Module (ECM) connector.

Turn the ignition on.

Using a 12 volt test light connected to ground, check the (K343) Fused
ASD Relay Output 2 circuit in the Fuel Pump Relay connector.

NOTE: The test light should be illuminated and bright. Compare
the brightness to that of a direct connection to the battery.

Is the test light illuminated and bright?

Yes

>> Go to 5

No

>> Repair the (K343) Fused ASD Relay Output 2 circuit for an

open circuit or high resistance.

Perform the ECM Verification Test Ver. 1. (Refer to 9 -
ENGINE - DIAGNOSIS AND TESTING)

5.

FUEL PUMP RELAY

Connect the Engine Control Module (ECM) connector.

Install a known good relay in place of the vehicle’s Fuel Pump Relay.

Turn the ignition on.

With the scan tool, Clear DTCs.

With the scan tool, actuate the Fuel Pump Relay.

Monitor the scan tool for at least two minutes.

With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

>> Go to 6

No

>> Replace the Fuel Pump Relay in accordance with the Service Information.

Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

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6.

ENGINE CONTROL MODULE (ECM)

Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Fuel Pump Relay
and the Engine Control Module (ECM).

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 ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

No

>> Replace the Engine Control Module (ECM) in accordance with the Service Information.

Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

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P0628-FUEL PUMP CONTROL CIRCUIT LOW

For a complete wiring diagram Refer to Section 8W

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