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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 2354 (WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - D THROUGH E)COMPONENT CONNECTOR END VIEWS - D THROUGH EENGINE CONTROL MODULE (ECM) X3 (LH2)
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6

Engine Control Module (ECM) X3 (LH2)

2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Engine Control Module (ECM) X3 (LH2)
WARNING: This page is about a different car, the 2010 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Engine Control Module (ECM) X3 (LH2)
GM1650395Courtesy of GENERAL MOTORS CORP.
Engine Control Module (ECM) X3 (LH2)

Pin Wire Circuit Function
1-2 - - Not Used
3 0.5 TN/WH 3211 HO2S Low Signal (Bank 2 Sensor 1)
4 0.5 PU/WH 3210 HO2S High Signal (Bank 2 Sensor 1)
5 0.5 PU 3220 HO2S High Signal (Bank 2 Sensor 2)
6 0.5 TN 3221 HO2S Low Signal (Bank 2 Sensor 2)
7 0.5 OG 225 Generator Turn On Signal
8-14 - - Not Used
15 0.5 L-GN 3212 HO2S Heater Low Control (Bank 2 Sensor 1)
16-20 - - Not Used
21 0.35 BK/WH 2751 Low Reference
22 - - Not Used
23 0.5 OG/BK 469 Low Reference
24-28 - - 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 TN 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
40-45 - - Not Used
46 0.5 OG/BK 1786 Park/Neutral Signal
47 - - Not Used
48 0.5 D-GN/WH 428 EVAP Canister Purge Solenoid Control
49 0.35 D-GN 335 Low Speed Cooling Fan Relay Control
50 0.5 OG/WH 3223 HO2S Heater Low Control (Bank 2 Sensor 2)
51-52 - - Not Used
53 0.5 TN/BK 2500 High Speed GMLAN Serial Data Bus +
54 - - Not Used
55 0.5 YE 410 ECT Sensor Signal
56 - - Not Used
57 0.5 OG/BK 380 A/C Refrigerant Pressure Sensor Signal
58 - - Not Used
59 0.5 L-GN 432 MAP Sensor Signal
60-72 - - Not Used
73 2 BK/WH 1551 Ground
Connector Part Information 
  • Harness: Engine
  • OEM: 34566-0203
  • Service: 88988372
  • Description: 73-Way F MX123 34566 Series (GY)
Terminal Part Information 
  • Pins: 3, 4, 5, 6, 7, 15, 23, 29, 33, 35, 37, 39, 46, 48, 50, 53, 55, 57, 59
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: J/J
  • Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)
  • Pins: 21, 49
  • Terminal/Tray: 33467-0003/23
  • Core/Insulation Crimp: H/H
  • Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)
  • Pin: 73
  • Terminal/Tray: 7116-4152-02/9
  • Core/Insulation Crimp: 2/5
  • Release Tool/Test Probe: 12094430/J-35616-35 (VT)
RENDER: 1.0x

NO RELATED

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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.