Fuel Injection ECM Pinouts
Scott Simpson
1986 & 1987 3.8 Liter Turbo Engine
This ECM Chart is for use with a digital voltmeter to further aid in diagnosis. The voltages you get may vary due to low battery or other reasons, but should be close. The ECM has 2 connectors: 1 24-pin (A&B) and a 32-pin (C&D)

The following conditions must be met before testing:

  • Engine at operating temperature, Diagnostic terminal not grounded,
  • Idling in closed loop (for "Eng. Run" column), ALDL tool not installed.

Key On Eng. Run.
CIRCUIT
PIN
WIRE
0* B+ Fuel Pump Relay A1 Green/Black
B+ 0*/B+ A/C Cluth Control A2 Light Green/Black
B+ B+ Canister Purge Control A3 Green/Yellow
B+ B+ EGR Control A4 Grey
0* B+ "SES" Control A5 Brown/White
B+ B+ IGN-ECM Fuse A6 Pink/Black
B+ B+ TCC Control ALDL A7 Tan/Black
4.3 varies 2-5 Serial Data ALDL A8 Orange
5.0 5.0 Diagnostic Term ALDL A9 White/Black
0* 0* Speed Sensor Signal A10 Dark Brown
0*/B+ B+ Cam Hi A11 Black
0* 0* Ground A12 Black/White
. . Not Used B1 .
. . Not Used B2 .
0* 0* Crank Reference Low B3 Black/Red
0* 0* EST Control B4 White
0*/B+ B+ Crank Reference High B5 Purple/White
2.50 2.48 MAF Sensor Signal B6 Yellow
8.71 8.75 ESC Signal B7 Yellow/Black
B+/0* B+/0* A/C Signal (On/Off) B8 Light Blue
. . Not Used B9 .
0* 0* Park/Neutral Switch B10 Orange/Black
. . Not Used B11 .
B+ B+ Injector #5 B12 Black/White
. . Not Used C1 .
. . Not Used C2 .
N/U N/U Idle Air Control B Lo C3 Green/Black
N/U N/U Idle Air Control B Hi C4 Green/White
N/U N/U Idle Air Control A Hi C5 Blue/White
N/U N/U Idle Air Control A Lo C6 Blue/Black
0* 0* 3rd Gear Signal C7 Green/White
0* 0* 4th Gear Signal C8 Light Blue
. . Not Used C9 .
2.04 2.18 Coolant Temp. Signal C10 Yellow
2.46 2.09 Mass Air Temp. Signal C11 Tan
B+ B+ Injector #6 C12 Black/Yellow
.36-.44 .36-.44 TPS Signal C13 Dark Blue
5 5 TPS 5 volt Reference C14 Grey
B+ B+ Injector #2 C15 Black/Green
0* 0* Battery 12 volts C16 Orange
0* 0* Ground D1 Black/White
B+ B+ Low Speed Fan Control D2 Dark Green
B+ B+ Wastegate Control D3 Pink/White
. . Not Used D4 .
4.56 4.56 Bypass D5 Tan/Black
0* 0* O2 Sensor Ground D6 Tan
0* 0* O2 Sensor Signal D7 Purple
. . Not Used D8 .
0* 0* EGR Diagnostic D9 Purple/White
0* 0* Ground D10 Black/White
. . Not Used D11 .
0* 0* TPS/CTS/MAT Ground D12 Black
. . Not Used D13 .
B+ B+ Injector #1 D14 Black
B+ B+ Injector #3 D15 Black/Pink
B+ B+ Injector #4 D16 Black/Red

Notes:

  • B+ Battery Positive voltage
  • * Less than 1 volt
  • 1. VSS varies from .45 to B+ depending on speed
  • 2. CTS at Normal Operating Temperature
  • 3. A8 & D7 varies
  • 4. A1 is B+ first two or three seconds
  • 5. A11 & B5 Depends on vane position in relation to "hall effect" switch. Voltage is low when vane is passing through switch.
  • 6. A2 & B8 Engine running, voltage will be high or low, dpending on whether A/C is on or off.
  • 7. N/U is Not Useable

From the GM Chassis Service Manual


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