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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 P2120TEST 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.
- 12: This test isolates whether the short is to another TAC System circuit in the harness or within the TAC module.
- 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 P2120
| 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 P0120 or U0107 is also set, refer to the appropriate DTC for further diagnosis.
|
0.24-2.24 V | Go to Step 3 | Go to Step 6 |
| 3 | Depress the accelerator pedal to the wide open throttle (WOT) position. Does the scan tool indicate APP sensor 1 voltage within the specified values? |
0.24-4.49 V | Go to Step 4 | Go to Step 6 |
| 4 |
|
- | Go to Step 24 | Go to Step 5 |
| 5 |
|
- | Go to Step 19 | Go to Diagnostic Aids |
| 6 | Disconnect the APP sensor harness connector. Does the scan tool indicate the APP sensor 1 voltage is at the specified value? |
0 V | Go to Step 7 | Go to Step 11 |
| 7 | Connect a test lamp between the APP sensor 1 signal circuit and B+. Does the scan tool indicate the APP sensor 1 voltage is at the specified value? |
5 V | Go to Step 8 | Go to Step 13 |
| 8 | Test the APP sensor 1, 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 10 | Go to Step 9 |
| 9 |
|
4.54-5.21 V | Go to Step 21 | Go to Step 16 |
| 10 |
|
0 V | Go to Step 19 | Go to Step 17 |
| 11 |
|
- | Go to Step 25 | Go to Step 12 |
| 12 |
|
- | Go to Step 25 | Go to Step 22 |
| 13 |
|
- | Go to Step 25 | Go to Step 14 |
| 14 | Test the APP sensor 1 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 15 |
| 15 |
|
- | Go to Step 25 | Go to Step 22 |
| 16 |
|
- | Go to Step 25 | Go to Step 22 |
| 17 |
|
- | Go to Step 25 | Go to Step 18 |
| 18 | Test the TAC module ground 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 22 |
| 19 | 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 20 |
| 20 | Replace the APP sensor assembly. Refer to Accelerator Pedal with Position Sensor Replacement
. Did you complete the repair? |
- | Go to Step 25 | - |
| 21 | Did DTC P0120 set while performing Step 9? | - | Go to DTC P0120 | Go to Step 22 |
| 22 | 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 23 |
| 23 | Replace the TAC module. Refer to Control Module References
for replacement, setup, and programming. Did you complete the replacement? |
- | Go to Step 25 | - |
| 24 | Repair the intermittent condition as necessary. Refer to Connector Repairs
and Wiring Repairs
. Did you complete the repair? |
- | Go to Step 25 | - |
| 25 |
|
- | 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 |
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When to See a Mechanic
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.