2007 Chevrolet Uplander Base, 3.9 WFACTORY OEM SERVICE PROCEDURE

Engine Control Module (ECM) Connector End View C1

Fig 1: ECM C1 Connector End View
GM1228485Courtesy of GENERAL MOTORS CORP.
Connector Part Information

Connector Part Information 
  • OEM: 34576-0703
  • Service: See Catalog
  • Description: 56-Way F MX123 Series Sealed (BK)
Terminal Part Information 
  • Pins: 9, 12-13, 15, 18-19, 29, 33-37, 40, 44, 47-49, 53-56
  • Terminal/Tray: 33467-0003/23
  • Core/Insulation Crimp: H/H
  • Release Tool/Test Probe: J-38125-213/J-35616-64A (L-BU)
  • Pins: 7, 20, 39
  • Terminal/Tray: 33467-0005/23
  • Core/Insulation Crimp: Pins 7, 39 - J/J
  • Core/Insulation Crimp: Pins 20 - K/K
  • Release Tool/Test Probe: J-38125-213/J-35616-64A (L-BU)
Connector Terminal Identification

Pin Wire Color Circuit No. Function
1-6 - - Not Used
7 L-GN 526 Stop Lamp Supply Voltage
8 - - Not Used
9 TN 2759 Low Reference
10-11 - - Not Used
12 BN/WH 419 MIL Control
13 D-GN/WH 465 Fuel Pump Relay Control
14 - - Not Used
15 D-GN 1049 Class 2 Serial Data
16-17 - - Not Used
18 BN 1141 Ignition 3 Voltage
19 PK 439 Ignition 1 Voltage
20 RD/WH 540 Battery Positive Voltage
21-28 - - Not Used
29 GY 1884 Cruise Control Switch Signal
30-32 - - Not Used
33 WH/BK 1164 5-Volt Reference
34 GY 2709 5-Volt Reference
35 TN 1274 5-Volt Reference
36 BN 1271 Low Reference
37 PU 1272 Low Reference
38 - - Not Used
39 D-GN 389 Vehicle Speed Signal
40 BN 5069 Powertrain Relay Control
41-43 - - Not Used
44 PU 1589 Fuel Level Sensor Signal
45-46 - - Not Used
47 D-BU 1161 APP Sensor 1 Signal
48 D-GN 890 Fuel Tank Pressure Sensor Signal
49 L-BU 1162 APP Sensor 2 Signal
50-52 - - Not Used
53 D-GN/WH 459 A/C Compressor Clutch Relay Control
54 D-BU 473 High Speed Cooling Fan Relay Control
55 WH 1310 EVAP Canister Vent Solenoid Control
56 YE/BK 625 Starter Enable Relay Control
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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