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Home >> Cadillac >> 2004 >> CTS Base, 3.6 7 >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 12 (Engine Controls - 2.6L & 3.2L - Diagnosis (DTC P0030 - P0174)) >> Diagnostic Trouble Codes >> DTC P0122 >> Test Description

Test Description

WARNING: This page is about a different variant/trim than selected.

The numbers below refer to the step numbers on the diagnostic table.

  1. 4:  The ECM performs a comparison of the signals from both throttle position sensors during the entire range of operation. If the DTC does not set with the key ON and the accelerator pedal released, actuating the throttle may cause the DTC to set.
  2. 6:  This step tests for the proper operation of the TP sensor 1 signal circuit. The ECM supplies a pull up voltage of about 4.8 volts on the signal circuit.
  3. 7:  This step is to test the integrity of the low reference circuit through the ECM.
  4. 10:  The 5-volt reference for the TP sensors and the accelerator pedal position (APP) sensor 2 are connected inside the ECM. This step is to determine if the APP sensor is affecting the 5-volt reference circuit of the TP sensors.
DTC P0122

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Engine Control Module (ECM) Connector End Views  or  Engine Controls Connector End Views 
1 Did you perform the Diagnostic System Check-Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls
2
  1. Turn ON the ignition, with the engine OFF.
  2. Observe the throttle position (TP) sensor 1 voltage with a scan tool.
Is the TP sensor 1 voltage less than the specified value?		 0.2 V Go to Step 5  Go to Step 3 
3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text or as close to the Freeze Frame/Failure Records that you observed.
Did the DTC fail this ignition?		 - Go to Step 5  Go to Step 4 
4 
  1. Clear the DTCs with a scan tool.
  2. Slowly depress the accelerator pedal to wide-open throttle (WOT) and then slowly return it to the closed position.
  3. Repeat this action several times.
Did the DTC fail this ignition?		 - Go to Step 18  Go to Intermittent Conditions
5
  • Turn OFF the ignition.
  • Disconnect the throttle body harness connector. Refer to Throttle Body Assembly Replacement .
  • Turn ON the ignition, with the engine OFF.
  • Measure the voltage from the 5-volt reference circuit of the TP sensor to a good ground with a DMM.
Is the voltage within the specified range?		 4.8-5.2 V Go to Step 6  Go to Step 10 
6  Measure the voltage from the signal circuit of the TP sensor 1 to a good ground with a DMM.
Is the voltage within the specified range?		 4.6-4.9 V Go to Step 7  Go to Step 12 
7 
  1. Turn OFF the ignition for 30 seconds.
    2. IMPORTANT: It may be necessary to remove the ECM/TCM fuse to allow the ECM to power down.
  2. Allow the engine control module (ECM) to completely power down. This can be verified by the loss of communication on the scan tool.
  3. Measure the resistance from the low reference circuit of the TP sensor to a good ground with the DMM.
Is the resistance less than the specified value?		 5ohm Go to Step 15  Go to Step 8 
8 Test the low reference circuit of the TP sensor 1 for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 20  Go to Step 9 
9 Measure the resistance from the case of the ECM to battery ground.
Is the resistance less than the specified value?		 5ohm Go to Step 16  Go to Step 14 
10 
  1. Turn OFF the ignition.
  2. Disconnect the accelerator pedal position (APP) sensor harness connector. Refer to Accelerator Pedal Position (APP) Sensor Replacement .
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the 5-volt reference circuit of the TP sensor 1 to a good ground with a DMM.
Is the voltage within the specified range?		 4.8-5.2 V Go to Step 17  Go to Step 11 
11
  1. Test the 5-volt reference circuit of the TP sensor for the following conditions:
    • A short to ground
    • High resistance
    • An open circuit
  2. Repair as necessary. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 20  Go to Step 13 
12
  1. Test the signal circuit of the TP sensor 1 for the following conditions:
    • A short to ground
    • A short to the low reference circuit
    • High resistance
    • An open circuit
  2. Repair as necessary. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 20  Go to Step 16 
13 Test the 5-volt reference circuit of the APP sensor 2 for a short to ground. Refer to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 20  Go to Step 16 
14 Repair the open or high resistance in the ECM ground circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 20  -
15 Test for an intermittent and for a poor connection at the at the TP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 20  Go to Step 18 
16 Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 20  Go to Step 19 
17 Replace the APP sensor. Refer to Accelerator Pedal Position (APP) Sensor Replacement .
Did you complete the replacement?		 - Go to Step 20  -
18 Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement .
Did you complete the replacement?		 - Go to Step 20  -
19 Replace the ECM. Refer to Engine Control Module (ECM) Replacement .
Did you complete the replacement?		 - Go to Step 20  -
20
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?		 - Go to Step 2  Go to Step 21 
21 Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List System OK
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