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HOMESERVICE MANUALSCHEVROLET2006SUBURBAN C1500, 5.3 ZREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 3 (ENGINE CONTROL SYSTEM - 8.1L - DTC P0506 TO DTC U0107)DTC P2125TEST DESCRIPTION
2006 Chevrolet Suburban C1500, 5.3 Z

Test Description

2006 Chevrolet Suburban C1500, 5.3 ZSECTION 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. 2:  The throttle position (TP) sensor 2 and the APP sensor 2 share a common 5-volt reference source. Diagnose DTC P0220 first if P0220 is also set.
  2. 18:  This test determines whether or not the TAC module can recognize a change in signal voltage.
  3. 19:  There are 2 separate 5-volt reference sources within the TAC module. The TP sensor 1 and the APP sensor 1 share one 5-volt reference source. The TP sensor 2 and the APP sensor 2 share another common 5-volt reference source. This test determines whether the signal circuit is shorted to any one of the 5-volt reference circuits. If a short exists, the corresponding sensor voltage will be pulled low.
  4. 20:  The previous step found the signal circuit and a 5-volt reference circuit shorted together. This test isolates whether the short is in the harness or within the TAC module.
  5. 26:  When the TAC module detects a condition within the TAC System, more than 1 TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
DTC P2125

Step Action Values Yes No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Powertrain Control Module (PCM) Connector End Views or Engine Controls Connector End Views
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2 
IMPORTANT: If DTC P0220 or U0107 is also set, refer to Diagnostic Trouble Code (DTC) List - Vehicle and diagnose the applicable DTC first.
  1. Turn ON the ignition, with the engine OFF, and with your foot OFF of the accelerator pedal.
  2. Observe the Accelerator Pedal Position (APP) Sensor 2 Voltage parameter with a scan tool.
Does the scan tool indicate APP sensor 2 voltage within the specified values?		 0.24-2.24 V Go to Step 3  Go to Step 6 
3 Fully depress the accelerator pedal to the wide open throttle (WOT) position.
Does the scan tool indicate APP sensor 2 voltage within the specified values?		 0.24-4.49 V Go to Step 4  Go to Step 6 
4
  1. Turn OFF the ignition for 15 seconds.
  2. Turn ON the ignition, with the engine OFF.
  3. Observe DTC info with a scan tool.
  4. Lightly touch and move the related engine wiring harnesses and connectors for the APP sensor while observing the DTC status.
  5. If the scan tool indicates this DTC failed this ignition during the above test, repair the intermittent condition as necessary. Refer to Wiring Repairs and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 25  Go to Step 5 
5 Slowly depress the accelerator pedal to WOT, then slowly return the pedal to closed throttle while observing the DTC status.
Did the scan tool indicate this DTC failed this ignition during the above test?		 - Go to Step 21  Go to Diagnostic Aids
6
  1. Disconnect the APP sensor harness connector.
  2. Test the APP sensor 2 signal circuit for voltage with a DMM.
Does the DMM indicate APP sensor 2 signal voltage within the specified values?		 3.94-6.06 V Go to Step 11  Go to Step 7 
7
  1. Turn OFF the ignition.
  2. Disconnect the throttle actuator control (TAC) module harness connector containing the APP sensor circuits.
  3. Turn ON the ignition, with the engine OFF.
  4. Test the APP sensor 2 signal circuit for a short to voltage with a DMM. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 25  Go to Step 8 
8 Test the APP sensor 2 signal circuit for an open or high resistance with a DMM. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 25  Go to Step 9 
9 Test the APP sensor 2 signal circuit for a short to ground with a DMM. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 25  Go to Step 10 
10 Test for a short between the APP sensor 2 signal circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 25  Go to Step 23 
11 Test the APP sensor 2, 5-volt reference circuit for voltage with a DMM.
Does the DMM indicate voltage within the specified values?		 4.54-5.21 V Go to Step 16  Go to Step 12 
12
  1. Turn OFF the ignition.
  2. Disconnect the TAC module harness connector containing the APP sensor circuits.
  3. Turn ON the ignition, with the engine OFF.
  4. Test the APP sensor 2, 5-volt reference circuit for a short to voltage with a DMM. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 25  Go to Step 13 
13 Test the APP sensor 2, 5-volt reference circuit for an open or high resistance with a DMM. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 25  Go to Step 14 
14 Test the APP sensor 2, 5-volt reference circuit for a short to ground with a DMM. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 25  Go to Step 15 
15 Test for a short between the APP sensor 2, 5-volt reference circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 25  Go to Step 23 
16 Measure resistance with a DMM connected between the APP sensor 2 low reference circuit and the APP sensor 1 low reference circuit.
Does the DMM indicate resistance within the specified values?		 0-5 ohm Go to Step 18  Go to Step 17 
17
  1. Turn OFF the ignition.
  2. Disconnect the TAC module harness connector containing the APP sensor circuits.
  3. Test the APP sensor 2 low reference circuit for an open or high resistance with a DMM. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 25  Go to Step 23 
18 
  1. Connect a fused jumper between the APP sensor 2 signal circuit and the APP sensor 2 low reference circuit at the APP sensor harness connector.
  2. Observe the APP Sensor 2 Voltage parameter with a scan tool.
Does the scan tool indicate APP sensor 2 voltage at the specified value?		 0 V Go to Step 19  Go to Step 23 
19 
  1. Observe the APP Sensor 1, APP Sensor 3 and TP Sensor 2 Voltage parameters with a scan tool.
  2. Connect a fused jumper between the APP sensor 2 signal circuit and the APP sensor 2 low reference circuit at the APP sensor harness connector.
Did the scan tool indicate a change in voltage in any of the parameters observed during the above test?		 - Go to Step 20  Go to Step 21 
20 
  1. Turn OFF the ignition.
  2. Disconnect the TAC module harness connectors.
  3. Test for a short between the APP sensor 2 signal circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 25  Go to Step 23 
21 Inspect for poor connections at the harness connector of the APP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals .
Did you find and correct the condition?		 - Go to Step 25  Go to Step 22 
22 Replace the APP sensor assembly. Refer to Accelerator Pedal with Position Sensor Replacement .
Did you complete the replacement?		 - Go to Step 25  -
23 Inspect for poor connections at the harness connector of the TAC module. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals .
Did you find and correct the condition?		 - Go to Step 25  Go to Step 24 
24 Replace the TAC module. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?		 - Go to Step 25  -
25
  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 26 
26  Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List - Vehicle System OK
RENDER: 1.0x

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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.