DTC P1218 Injection Pump Calibration Circuit. GMC Truck GMC P42 Commercial Chassis 1997

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 1997 🢒 GMC P42 Commercial Chassis 🢒 DTC 🢒 DTC P1218 Injection Pump Calibration Circuit

Engine Controls Components
Engine Controls (Cell 22: Fuel Controls 2)
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The PCM uses a calibrated resistor which is mounted internally in the injection pump in order to determine the fuel rates. The resistor value is stored in the PCM memory. If the PCM memory has been disturbed or the PCM has been replaced, the PCM will relearn the resistor value on the next ignition cycle.

Conditions for Setting the DTC

•	The PCM currently does not have a valid resistor valve.

•	The PCM is unable to read a resistor value.

Action Taken When the DTC Sets

•	The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive drive trip the diagnostic runs and fails.

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The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the Failure Records store this information. If the diagnostic reports a failure on the second consecutive drive trip, the Freeze Frame records the operating conditions at the time of failure and updates the Failure Records.

Conditions for Clearing the MIL/DTC

•	The PCM will turn the MIL off after three consecutive trips without a fault condition.

•	A History DTC will clear after forty consecutive warm-up cycles during which the diagnostic does not fail (the coolant temperature has risen 5°C (40°F) from the start up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle).

•	Use of a Scan Tool will clear the DTC codes.

Diagnostic Aids

Check the connection at fuel injector driver. Clear the DTC, and the cycle ignition. If the DTC clears, treat the condition as an intermittent.

Test Description

The numbers below refer to the step numbers on the Diagnostic Table.

This step will determine if there is a problem with the connection at the fuel solenoid driver or a malfunctioning injection pump.

Step	Action	Value(s)	Yes	No
1	Important: Before clearing any DTCs, use the Scan Tool Capture Info to save freeze frame and failure records for reference, as the Scan Tool loses data when using the Clear Info function. Was the Powertrain On-Board Diagnostic (OBD) System Check performed?	--	Go to Step 2	Go to A Powertrain On Board Diagnostic (OBD) System Check
2	Are than any other DTCs set?	--	Refer to the applicable DTC table	Go to Step 3
3	Check the connection at the Fuel Solenoid Driver. Clear the DTC and the cycle ignition. Start and idle engine. Activate Time set procedure (the diagnostic will only run when a Time Set procedure is performed). Exit out of Time set procedure and Select DTC, Specific, then enter the DTC number. Does the Scan Tool indicate that this diagnostic Ran and Passed?	--	Go to Step 5	Go to Step 4
4	Replace the injection pump. Refer to Fuel Injection Pump Replacement . Important: The new injection pump must be timed. Refer to Injection Timing Adjustment . Is the action complete?	--	Go to Step 6	--
5	The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If additional DTCs were stored, refer to those tables. Are any additional DTCs stored?	--	Go to the applicable DTC table	Go to Diagnostic Aids
6	Does the Scan Tool display any additional undiagnosed DTCs?	--	Go to the applicable DTC table	System OK