P1221

DTC P1221 Fuel Pump Secondary System Circuit Low:

Fuel Pump Relay Circuit:

CIRCUIT DESCRIPTION
The status of the fuel pump CKT 120 is monitored by the Vehicle Control Module-A (VCM-A) at terminal "BK14" and is used to compensate fuel delivery based on system voltage. This signal is also used to store a DTC if the fuel pump relay is defective or fuel pump voltage is lost while the engine is running. There should be about 12 volts on CKT 120 for at least 2 seconds after the ignition is turned "ON," or when reference pulses are being received by the VCM-A.

The DTC will help the diagnosis of an engine that "Cranks But Will Not Run." DTC P1221 is a type "D" DTC.

DTC P1221 WILL SET WHEN
Ignition voltage is greater than 9 volts. Voltage at "GR20" is less than 2 volts for 0.5 seconds key "ON" engine "OFF" or 4 seconds with key "ON" engine "ON" since the last reference pulse.

ACTION TAKEN (VCM-A WILL DEFAULT TO)
No action taken. The oil pressure switch will provide voltage to the fuel pump when it closes. This could result in an extended crank time, especially when cold.

DTC P1221 WILL CLEAR WHEN
The VCM-A will turn the MIL "OFF" after three consecutive trips without a fault condition present. A history DTC will be cleared if no fault conditions have been detected for forty warm-up cycles [coolant temperature has risen 22°C (40°F) from start-up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle] or the Tech 1 clearing feature has been used.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Check to see if DTC P1221 was set as result of a hard failure or intermittent condition.
2. Checks pump relay.
3. Checks CKTs 440 and 151.
4. Checks CKT 465 connections at relay and VCM-A.
5. Checks oil pressure switch and connections.

DIAGNOSTIC AIDS
Fuel pump should run for 2 seconds and then turn "OFF" if the VCM-A senses no reference pulses. The fuel pump relay is located in the glove box.