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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G3500, VAN PASSENGER EXTENDEDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 131 (WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT VIEWS & COMPONENT CONNECTOR END VIEWS)COMPONENT CONNECTOR END VIEWSENGINE CONTROL MODULE (ECM) X1 (LZ4)
2008 Chevrolet Chevy Express G3500, Van Passenger Extended

Engine Control Module (ECM) X1 (LZ4)

2008 Chevrolet Chevy Express G3500, Van Passenger ExtendedSECTION Engine Control Module (ECM) X1 (LZ4)
WARNING: This page is about a different car, the 2008 Chevrolet Malibu Classic. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Engine Control Module (ECM) X1 (LZ4) Connector End View
GM1650395Courtesy of GENERAL MOTORS CORP.
Engine Control Module (ECM) X1 (LZ4)

Pin Wire Circuit Function
1 0.35 OG/BK 1786 Park/Neutral Signal
2-8 - - Not Used
9 0.35 WH 17 Stop Lamp Supply Voltage
10 0.35 PU 3120 HO2S High Signal (Bank 1 Sensor 2)
11 0.35 TN/WH 3121 HO2S Low Signal (Bank 1 Sensor 2)
12 0.35 OG/BK 380 A/C Refrigerant Pressure Sensor Signal
13 0.35 TN 5514 Low Reference
14-15 - - Not Used
16 0.35 PU 1589 Fuel Level Sensor Signal
17 0.35 D-BU 473 High Speed Cooling Fan Relay Control
18 0.35 BN 4 Accessory Voltage
19 0.35 PK 639 Ignition 1 Voltage
20 0.35 RD/WH 540 Battery Positive Voltage
21-22 - - Not Used
23 0.35 PU 1272 Low Reference
24 0.35 D-GN 890 Fuel Tank Pressure Sensor Signal
25-26 - - Not Used
27 0.35 TN 2501 High Speed GMLAN Serial Data Bus-
28 0.35 TN/BK 2500 High Speed GMLAN Serial Data Bus+
29 0.35 D-BU 1161 APP Sensor 1 Signal
30 0.35 BN 1271 Low Reference
31 0.35 OG/BK 1057 Low Reference
32 0.35 L-BU 1162 APP Sensor 2 Signal
33 0.35 GY 705 5-Volt Reference 1
34 0.35 GY 2700 5-Volt Reference 1
35 - - Not Used
36 0.35 TN 1274 5-Volt Reference 1
37 0.35 TN 472 IAT Sensor Signal
38 0.35 TN/BK 2760 Low Reference
41 0.35 YE 492 MAF Sensor Signal
42-46 - - Not Used
47 0.8 PK/BK 5290 Ignition 1 Voltage
48 0.35 BN 818 Vehicle Speed Signal
49 0.35 TN 3221 HO2S Low Signal (Bank 2 Sensor 2)
50 0.35 D-GN/WH 465 Fuel Pump Relay Control
51 - - Not Used
52 0.35 PU/WH 6386 Starter Relay Coil Control
53-55 - - Not Used
56 0.35 WH/BK 1164 5-Volt Reference 2
57 - - Not Used
58 0.35 D-GN 335 Low Speed Cooling Fan Relay Control
59 0.35 BN 5069 Main Relay Control
60 0.35 TN 2759 Low Reference
61 0.35 WH 1310 EVAP Canister Vent Solenoid Control
62 - - Not Used
63 0.35 D-GN/WH 459 A/C Compressor Clutch Relay Control
64 0.35 OG/WH 3223 HO2S Heater Low Control (Bank 2 Sensor 2)
65 0.35 GY/WH 3122 HO2S Heater Low Control (Bank 2 Sensor 1)
66-67 - - Not Used
68 0.35 BN/WH 419 MIL Control
69 0.35 PU 3220 HO2S High Signal (Bank 2 Sensor 2)
70-72 - - Not Used
73 2 BK 451 Ground
Connector Part Information 
  • OEM: 13542537
  • Service: See Catalog
  • Description: 73-Way F MX123 34566 Series Sealed (BK)
Terminal Part Information 
  • Pins: 1, 9, 12-13, 16-20, 23-24, 27-34, 36, 48, 50, 52, 56, 58-61, 63-65, 68
  • Terminal/Tray: 33467-0003/23
  • Core/Insulation Crimp: H/H
  • Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)
  • Pins: 10-11, 37-38, 41, 47, 49, 69
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: Pins 10, 11, 47, 49, 69 - K/K
  • Core/Insulation Crimp: Pins 37, 38, 41 - J/J
  • Release Tool/Test Probe: J-38125-213/J-35616-64B (L-BU)
  • Pins: 73
  • Terminal/Tray: 7116-4152-02/9
  • Core/Insulation Crimp: 2/5
  • Release Tool/Test Probe: 12094430/J-35616-35 (VT)
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.