2008 Cadillac STS VFACTORY OEM SERVICE PROCEDURE

Engine Control Module (ECM) X2 (LLT)

Fig 1: Engine Control Module (ECM) X2 (LLT) Connector End View
GM1826273Courtesy of GENERAL MOTORS CORP.
Engine Control Module (ECM) X2 (LLT)

Pin Wire Circuit Function
1 0.5 BK/WH 1551 Ground
2 0.5 BK/WH 1551 Ground
3 0.75 PK/BK 5290 Ignition 1 Voltage
4 0.5 BK/WH 1551 Ground
5 0.75 PK/BK 5290 Ignition 1 Voltage
6 0.75 PK/BK 5290 Ignition 1 Voltage
7 0.5 GY/WH 3122 HO2S Heater Low Control (Bank 2 Sensor 1)
8 - - Not Used
9 0.5 TN 2759 Low Reference
10 0.5 D-GN/WH 465 Fuel Pump Relay Control
11 0.35 TN 5514 Low Reference
12 0.35 YE 447 Starter Relay Coil Control
13 0.5 YE 492 MAF Sensor Signal
14 0.5 GY 2709 5-Volt Reference
15 0.5 D-BU 1161 APP Sensor 1 Signal
16 - - Not Used
17 0.5 OG/BK 1786 Ignition Lock Cylinder Control Actuator Signal
18 - - Not Used
19 0.75 WH 1310 EVAP Canister Vent Solenoid Control
20 0.5 OG/WH 3223 HO2S Heater Low Control (Bank 2 Sensor 2)
21 0.5 BN/WH 419 MIL Control
22 0.5 TN 2760 Low Reference
23 0.5 TN/WH 3121 HO2S Heater Low Signal (Bank 2 Sensor 2)
24 0.5 TN 3221 HO2S Heater Low Signal (Bank 2 Sensor 2)
25 0.5 L-BU 1162 APP Sensor 2 Signal
26 0.5 L-BU 1937 Fuel Gauge Sensor Signal
27 0.5 D-GN 890 Fuel Tank Pressure Sensor Signal
28-33 - - Not Used
34 0.5 BN 1271 Low Reference
35 0.75 GY 2700 5-Volt Reference
36 0.5 D-BU 1936 Fuel Level Sensor Signal
37 - - Not Used
38 0.5 PU 3120 HO2S High Signal (Bank 1 Sensor 2)
39 0.5 OG/BK 380 A/C Refrigerant Pressure Sensor Signal
40 - - Not Used
41 0.35 YE/BK 5728 ECM/TCM Serial Data Wake Up
42 0.35 TN/BK 2500 High Speed GMLAN Serial Data Bus +
43 - - Not Used
44 0.5 D-GN/WH 459 A/C Compressor Clutch Relay Control
45 0.5 D-BU 473 High Speed Cooling Fan Relay Control
46 0.5 D-GN 335 Low Speed Cooling Fan Relay Control
47 0.5 PU 1272 Low Reference
48 0.5 TN 1274 5-Volt Reference
49 0.5 WH/BK 1164 5-Volt Reference
50 0.5 L-BU 6289 IAT Sensor Signal
51 0.5 PU 3220 HO2S High Signal (Bank 2 Sensor 2)
52 0.5 WH 17 Stop Lamp Switch Signal
53 - - Not Used
54 0.75 PK 239 Ignition 1 Voltage
55 0.35 TN 2501 High Speed GMLAN Serial Data Bus -
56 0.35 RD/WH 1440 Battery Positive Voltage
57 - - Not Used
58 0.5 BN 5069 Main Relay Control
Connector Part Information 
  • OEM: 1928404780
  • Service: 88988935
  • Description: 58-Way F 2.8 Series Sealed (BK)
Terminal Part Information 
  • Pins: See Terminal Repair Kit
  • Terminal/Tray: See Terminal Repair Kit
  • Core/Insulation Crimp: Pins See Terminal Repair Kit
  • Release Tool/Test Probe: See Terminal Repair Kit
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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