Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
SYS.OK|MANUAL.DBβ LIVE
HOMESERVICE MANUALSPONTIAC1991FIREBIRD V8-350 5.7LREPAIR AND DIAGNOSISDIAGRAMSELECTRICAL DIAGRAMSPOWERTRAIN MANAGEMENTSYSTEM DIAGRAMELECTRONIC/POWERTRAIN CONTROL MODULE (ECM/PCM)
1991 Pontiac Firebird V8-350 5.7L
Electronic/Powertrain Control Module (ECM/PCM)
1991 Pontiac Firebird V8-350 5.7LSECTION Electronic/Powertrain Control Module (ECM/PCM)
ECM Wiring Diagram (Part 1 Of 4):
GE12 = DIAGNOSTIC TEST
BD1 = SYSTEM GROUND
BA12 = SYSTEM GROUND
BD7 = INJECTOR DRIVER GROUND
BA8 = SERIAL DATA
BD6 = INJECTOR DRIVER GROUND
GE15 = OXYGEN SENSOR GROUND
GE14 = OXYGEN SENSOR SIGNAL
GF10 = VATS SIGNAL
BB9 = VSS (LOW)
BB10 = VSS (HIGH)
BB11 = VSS OUTPUT (4000 P/M)
BC1 = VSS OUTPUT (2000 P/M)
GF16 = MAT SIGNAL
BB5 = SENSOR GROUND
GF13 = TPS SIGNAL
BA5 = +5 VOLT REFERENCE
BA4 = +5 VOLT REFERENCE
GF15 = MAP SIGNAL
BB6 = SENSOR GROUND
GE16 = COOLANT TEMPERATURE SENSOR
GF9 = KNOCK SIGNAL
ECM Wiring Diagram (Part 2 Of 4):
GE3 = IAC COIL "A" HI
GE4 = IAC COIL "A" LO
GE5 = IAC COIL "B" HI
GE6 = IAC COIL "B" LO
BD16 = PARK NEUTRAL SWITCH (A/T ONLY)
BA6 = IGNITION
BC11 = INJECTOR DRIVER
BC12 = INJECTOR DRIVER
BC8 = EST
BD8 = REFERENCE
BC7 = BYPASS
BD9 = REFERENCE LOW
BC16 = B+
BB1 = B+
BA11 = FUEL PUMP RELAY DRIVE (12V)
BD1 = SYSTEM GROUND
GE13 = FUEL PUMP SIGNAL
ECM Wiring Diagram (Part 3 Of 4):
GF1 = M/T SHIFT LIGHT CONTROL
GE7 = "SERVICE ENGINE SOON LIGHT" CONTROL
BD14 = 4TH GEAR SWITCH
GF6 = A/T TCC CONTROL
GF7 = CANISTER PURGE CONTROL
GE9 = EGR SOLENOID CONTROL
GF4 = AIR CONVERTER SOLENOID CONTROL
GF2 = AIR PORT SOLENOID CONTROL
ECM Wiring Diagram (Part 4 Of 4):
BC9 = A/C REQUEST SIGNAL
GE8 = COOLING FAN CONTROL
BD12 = FAN REQUEST SIGNAL
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:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.