DTC P0221 Accelerator Pedal Position (APP) Sensor 2 Circuit Performance. GMC Truck Savana 1999

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 1999 🢒 Savana 🢒 Engine 🢒 Engine Controls - 6.5L (L65) 🢒 DTC P0221 Accelerator Pedal Position (APP) Sensor 2 Circuit Performance

Engine Controls Components
Cell 22: Cruise Controls
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The accelerator pedal position (APP) module provides a voltage signal that changes relative to accelerator position. There are three differently scaled sensors located within the APP module.

Conditions for Running the DTC

•	The ignition voltage is greater than 6.4 volts.

•	The engine speed is greater than 300 RPM.

•	There are no in range faults for APP 1 or APP 3 [powertrain control module (PCM) checks for high and low voltage faults].

Conditions for Setting the DTC

•	The difference between APP 2 and APP 3 is greater than 0.50 volts [PCM compares pre-scaled voltage (internal to PCM)].

•	The difference between APP 2 and APP 1 is greater than 0.23 volts [the PCM compares the pre-scaled voltage (internal to the PCM)].

•	The conditions were met for 2 seconds.

Action Taken When the DTC Sets

•	The service throttle soon lamp will not illuminate when one APP DTC sets. The PCM will only illuminate the service throttle soon lamp when multiple APP DTCs set.

•	The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Failure Records.

Conditions for Clearing the MIL/DTC

•	The PCM will turn the MIL off after 3 consecutive trips without a fault condition.

•	A history DTC clears after 40 consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.

•	The scan tool Clear Info function was used.

There are no driveability issues associated with the APP module unless a DTC is present. The most likely cause of this DTC are poor connections or the sensor itself. The least likely is a powertrain control module (PCM) problem.

An intermittent may be caused by the following:

•	Poor connections

•	A rubbed through wire insulation

•	Broken wire inside the insulation

A scan tool reads the APP 2 position in volts and should read about 4.5 volts with the throttle closed and the ignition ON or at idle. The voltage should decrease at a steady rate as the throttle is moved toward wide open throttle (WOT). Also, 90 percent pedal travel is acceptable for correct APP operation. Scan the APP 2 sensor while depressing the accelerator pedal with the engine stopped and the ignition ON. The display should vary from about 4.5 volts when the throttle is closed to about 1.5 volts when the throttle is held at the WOT position.

Test Description

The number(s) below refer to the step number(s) on the Diagnostic Table.

This step determines if there is a good 5 volt reference.

This step will check for an open in the ground circuit.

Step	Action	Value(s)	Yes	No
1	Important: Before clearing any DTCs, use the scan tool Capture Info function to save the Freeze Frame and the Failure records for reference. The control module's data is deleted once the Clear Info function is used. Was the Powertrain On-Board Diagnostic (OBD) System Check performed?	--	Go to Step 2	Go to Powertrain On Board Diagnostic (OBD) System Check
2	Turn the ignition ON with the engine OFF. With the throttle closed, observe APP voltages on the scan tool. Are the APP voltages at the specified values (values are listed as APP 1, APP 2, and APP 3 respectively)?	0.45-0.95 V 4.0- 4.5 V 3.6- 4.0 V	Go to Step 3	Go to Step 4
3	The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If any additional DTCs are stored, refer to the applicable DTC table(s) first. Are there any additional DTCs stored?	--	Go to the applicable DTC Table	Go to Diagnostic Aids
4	Disconnect the APP sensor electrical connector. Turn the ignition ON, leaving the engine OFF. With J 39200 DMM connected to ground, probe the APP sensor 5 volt reference circuits at APP harness terminals G, D, and E. Is the voltage greater than or equal to the specified value on all of the circuits?	4.75 V	Go to Step 5	Go to Step 6
5	Turn the ignition ON with the engine OFF. With a J 35616-200 unpowered test lamo connected to B+, probe the APP sensor ground circuits at APP sensor harness terminals A, B, and J. Is the Test lamp ON (all circuits)?	--	Go to Step 9	Go to Step 8
6	Turn the ignition OFF. Disconnect the PCM and check the 5 volt reference circuit for an open or a short to ground. If the 5 volt reference circuit is open or shorted to ground, repair as necessary. Refer to Wiring Repairs . Did you perform a repair?	--	Go to Step 11	Go to Step 7
7	Check the 5 volt reference circuit for a poor connection at the PCM and the replace terminal if necessary. Refer to Wiring Repairs . Did you perform a repair?	--	Go to Step 11	Go to Step 10
8	Turn the ignition OFF. Disconnect the PCM and check for an open sensor ground circuit to the PCM. If a problem is found, repair as necessary. Refer to Wiring Repairs . Did you perform a repair?	--	Go to Step 11	Go to Step 10
9	Replace the APP module. Refer to Accelerator Pedal Position Module Replacement . Is the action complete?	--	Go to Step 11	--
10	Important: The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete?	--	Go to Step 11	--
11	Using the scan tool, clear the DTCs. Start the engine. Allow the engine to idle until the normal operating temperature is reached. Select DTC and the Specific DTC function. Enter the DTC number that was set. Operate the vehicle within the Conditions for Setting this DTC until the scan tool indicates the diagnostic Ran. Does the scan tool indicate the diagnostic Passed?	--	Go to Step 12	Go to Step 2
12	Does the scan tool display any additional undiagnosed DTCs?	--	Go to the applicable DTC Table	System OK