Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2008 Hummer H3 Base, AutomaticFACTORY OEM SERVICE PROCEDURE
Engine Control Module (ECM) X2
Engine Control Module (ECM) X2
| Pin | Wire | Circuit | Function |
|---|---|---|---|
| 1 | 0.5 PU | 2121 | IC 1 Control |
| 2 | 0.5 TN | 1664 | HO2S Low Signal - Bank 1 Sensor 1 (LH8) |
| 0.5 TN/WH | 1653 | HO2S Low Signal Sensor 1 (LLR) | |
| 3 | 0.5 PU/WH | 1665 | HO2S High Signal - Bank 1 Sensor 1 (LH8) |
| 0.5 D-GN | 1655 | HO2S High Signal - Sensor 1 (LLR) | |
| 4 | 0.5 PU/WH | 1668 | HO2S High Signal - Bank 1 Sensor 2 (LH8) |
| HO2S High Signal - Sensor 2 (LLR) | |||
| 5 | 0.5 TN/WH | 1669 | HO2S Low Signal - Bank 1 Sensor 2 (LH8) |
| HO2S Low Signal - Sensor 2 (LLR) | |||
| 6 | 0.8 L-BU | 1876 | Knock Sensor 2 Signal (LH8) |
| 7 | 0.8 GY | 2303 | Knock Sensor 2 Signal (LH8) |
| 8 | 0.8 D-BU | 496 | Knock Sensor 1 Signal (LH8) |
| 0.5 L-BU | 1876 | Knock Sensor Signal (LLR) | |
| 9 | 0.8 GY | 1716 | Knock Sensor 1 Signal (LH8) |
| 0.5 GY | 2303 | Knock Sensor Signal (LLR) | |
| 10 | - | - | Not Used |
| 11 | 0.5 YE | 581 | TAC Motor Control - 1 |
| 12 | 0.5 BN | 582 | TAC Motor Control - 2 |
| 13 | 0.5 PK | 739 | Ignition Voltage |
| 14 | 0.5 BN | 2198 | CMP Actuator Solenoid High Control (LLR) |
| 15 | - | - | Not Used |
| 16 | 0.8 PK/BK | 1746 | Fuel Injector 3 Control (LH8) |
| 17 | 0.5 PU/WH | 2128 | IC 8 Control (LH8) |
| 0.5 L-BU | 2123 | IC 3 Control (LLR) | |
| 18 | 0.5 D-GN/WH | 2124 | IC 4 Control (LH8) |
| 19 | 0.5 BN/WH | 2130 | Low Reference (LH8) |
| 20-22 | - | - | Not Used |
| 23 | 0.5 OG | 6260 | Low Reference (LH8) |
| 0.5 PK/BK | 632 | CMP Sensor Signal (LLR) | |
| 24 | 0.5 BK | 2755 | Low Reference |
| 25-26 | - | - | Not Used |
| 27 | 0.5 GY/BK | 6272 | Low Reference (LH8) |
| 0.5 D-BU/WH | 1869 | Low Reference (LLR) | |
| 28 | - | - | Not Used |
| 29 | 0.5 BK | 2752 | Low Reference |
| 30-31 | - | - | Not Used |
| 32 | 0.8 L-GN/BK | 1745 | Fuel Injector 2 Control (LH8) |
| 0.5 L-BU/BK | 844 | Fuel Injector 4 Control (LLR) | |
| 33 | 0.5 RD | 2127 | IC 7 Control (LH8) |
| 0.5 D-GN | 2125 | IC 5 Control (LLR) | |
| 34 | 0.5 D-GN | 2125 | IC 5 Control (LH8) |
| 35 | 0.5 BN | 2129 | Low Reference (LH8) |
| 36-38 | - | - | Not Used |
| 39 | 0.5 D-BU | 6259 | 5-Volt Reference 1 (LH8) |
| 0.5 RD | 631 | 5-Volt Reference 2 (LLR) | |
| 40 | 0.5 GY | 2705 | 5-Volt Reference 1 |
| 41 | - | - | Not Used |
| 42 | 0.5 BK | 2760 | Low Reference |
| 43 | 0.5 PU/WH | 6270 | 5-Volt Reference 2 (LH8) |
| 0.5 L-GN | 1867 | 5-Volt Reference 2 (LLR) | |
| 44 | 0.5 GY | 2701 | 5-Volt Reference 2 |
| 45 | - | - | Not Used |
| 46 | 0.5 BK | 2199 | Low Reference (LLR) |
| 47 | - | - | Not Used |
| 48 | 0.8 D-BU/WH | 878 | Fuel Injector 8 Control (LH8) |
| 0.5 PK/BK | 1746 | Fuel Injector 3 Control (LLR) | |
| 49 | 0.8 BK/WH | 845 | Fuel Injector 5 Control (LH8) |
| 50-51 | - | - | Not Used |
| 52 | 0.8 YE/BK | 846 | Fuel Injector 6 Control (LH8) |
| 0.5 L-GN/BK | 1745 | Fuel Injector 2 Control (LLR) | |
| 53 | 0.5 RD/WH | 2122 | IC 2 Control (LH8) |
| 0.5 D-GN/WH | 2124 | IC 4 Control (LLR) | |
| 54 | 0.5 L-BU/WH | 2126 | IC 6 Control (LH8) |
| 0.5 RD/WH | 2122 | IC 2 Control (LLR) | |
| 55 | 0.5 L-BU | 2123 | IC 3 Control (LH8) |
| 56-58 | - | - | Not Used |
| 59 | 0.5 D-BU/WH | 6265 | CMP Sensor Signal (LH8) |
| 0.5 BK | 630 | Low Reference (LLR) | |
| 60 | 0.5 TN/WH | 331 | Oil Pressure Sensor Signal (LH8) |
| 61 | - | - | Not Used |
| 62 | 0.5 L-BU | 6289 | IAT Sensor Signal |
| 63 | 0.5 WH/BK | 6271 | CKP Sensor Signal (LH8) |
| 0.5 YE/BK | 1868 | CKP Sensor Signal (LLR) | |
| 64 | 0.5 D-GN | 485 | TP Sensor 1 Signal |
| 65 | - | - | Not Used |
| 66 | 0.5 PU | 486 | TP Sensor 2 Signal |
| 67 | 0.5 YE | 492 | MAF Sensor Signal |
| 68 | 0.5 BK/WH | 3113 | HO2S Heater Low Control - Bank 1 Sensor 1 (LH8) |
| 0.5 D-GN | 676 | HO2S Heater High Control - Sensor 1 (LLR) | |
| 69 | 0.5 BK/WH | 3122 | HO2S Heater Low Control - Bank 1 Sensor 2 (LH8) |
| 0.5 BK/WH | 1423 | HO2S Heater Low Control - Sensor 2 (LLR) | |
| 70 | 0.8 L-BU/BK | 844 | Fuel Injector 4 Control (LH8) |
| 71 | 0.8 RD/BK | 877 | Fuel Injector 7 Control (LH8) |
| 0.5 BK/WH | 845 | Fuel Injector 5 Control (LLR) | |
| 72 | 0.8 BK | 1744 | Fuel Injector 1 Control |
| 73 | 2 BK | 451 | Ground |
Connector Part Information
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Terminal Part Information
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Factory Service Tools
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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.
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