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 AlphaFACTORY OEM SERVICE PROCEDURE
Engine Control Module (ECM) X3
Engine Control Module (ECM) X3
| Pin | Wire | Circuit | Function |
|---|---|---|---|
| 1-2 | - | - | Not Used |
| 3 | 0.5 TN | 1667 | HO2S Low Signal - Bank 2 Sensor 1 (LH8) |
| 4 | 0.5 PU | 1666 | HO2S High Signal - Bank 2 Sensor 1 (LH8) |
| 5 | 0.5 PU | 1670 | HO2S High Signal - Bank 2 Sensor 2 (LH8) |
| 6 | 0.5 TN | 1671 | HO2S Low Signal - Bank 2 Sensor 2 (LH8) |
| 7 | 0.5 PU | 5428 | Generator Regulator Control |
| 8 | - | - | Not Used |
| 9 | 0.5 BN | 436 | AIR Relay Control (K18) |
| 10-11 | - | - | Not Used |
| 12 | 0.5 TN/BK | 464 | Delivered Torque Signal |
| 13-14 | - | - | Not Used |
| 15 | 0.5 L-GN | 3212 | HO2S Heater Low Control - Bank 2 Sensor 1 (LH8) |
| 16 | - | - | Not Used |
| 17 | 0.5 OG/BK | 463 | Requested Torque Signal |
| 18-20 | - | - | Not Used |
| 21 | 0.5 BK | 2751 | Low Reference |
| 22 | - | - | Not Used |
| 23 | 0.5 OG/BK | 469 | Low Reference |
| 24-25 | - | - | Not Used |
| 26 | 0.5 D-BU/WH | 6785 | Low Reference (K18) |
| 27 | 0.5 D-GN/WH | 6294 | Low Reference (MA5) |
| 28 | - | - | Not Used |
| 29 | 0.5 GY | 23 | Generator Field Duty Cycle Signal |
| 30-32 | - | - | Not Used |
| 33 | 0.5 TN | 2501 | High Speed GMLAN Serial Data Bus - |
| 34 | - | - | Not Used |
| 35 | 0.5 BK | 2761 | Low Reference |
| 36 | - | - | Not Used |
| 37 | 0.5 GY | 2700 | 5-Volt Reference 1 |
| 38 | - | - | Not Used |
| 39 | 0.5 GY | 2704 | 5-Volt Reference 1 |
| 40-41 | - | - | Not Used |
| 42 | 0.5 BN/WH | 6789 | 5-Volt Reference (K18) |
| 43 | 0.5 D-GN | 6293 | 5-Volt Reference (MA5) |
| 44-45 | - | - | Not Used |
| 46 | 0.5 D-GN | 1433 | PNP/Clutch Start Switch Signal (M30) |
| 47 | - | - | Not Used |
| 48 | 0.5 D-GN/WH | 428 | EVAP Canister Purge Solenoid Control |
| 49 | - | - | Not Used |
| 50 | 0.5 RD/WH | 3223 | HO2S Heater Low Control - Bank 2 Sensor 2 (LH8) |
| 51-52 | - | - | Not Used |
| 53 | 0.5 TN/WH | 2500 | High Speed GMLAN Serial Data Bus + |
| 54 | - | - | Not Used |
| 55 | 0.5 YE | 410 | ECT Sensor Signal |
| 56 | - | - | Not Used |
| 57 | 0.5 RD/BK | 380 | A/C Refrigerant Pressure Sensor Signal |
| 58 | - | - | Not Used |
| 59 | 0.5 L-GN | 432 | MAP Sensor Signal |
| 60-61 | - | - | Not Used |
| 62 | 0.5 YE | 6787 | Air Injection Reaction Control Valve Control (K18) |
| 63 | 0.5 D-BU | 6303 | CPP Sensor Signal (MA5) |
| 64 | - | - | Not Used |
| 65 | 0.5 TN/BK | 231 | Oil Pressure Switch Signal (LLR) |
| 66 | 0.5 PU/WH | 821 | VSS High Signal (MA5) |
| 67 | 0.5 L-GN/BK | 822 | VSS Low Signal (MA5) |
| 68-73 | - | - | Not Used |
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.