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.
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HOMESERVICE MANUALSCHEVROLET1991S10/T10 P/U 4WD V6-262 4.3LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTDIAGRAMSELECTRICAL DIAGRAMSELECTRONIC/POWERTRAIN CONTROL MODULE (ECM/PCM)ELECTRONIC/ENGINE CONTROL MODULE (ECM)
1991 Chevrolet S10/T10 P/U 4WD V6-262 4.3L
Electronic/Engine Control Module (ECM)
1991 Chevrolet S10/T10 P/U 4WD V6-262 4.3LSECTION Electronic/Engine Control Module (ECM)
ECM Wiring Diagram (Part 1 Of 4):
A8 = SERIAL DATA.
A9 = DIAGNOSTIC TEST.
A12 = SYSTEM GROUND.
D6 = OXYGEN SENSOR GROUND.
D1 = SYSTEM GROUND.
C9 = CRANK SIGNAL.
D7 = OXYGEN SENSOR SIGNAL.
D2 = MAP GROUND.
A11 = SYSTEM GROUND.
C10 = CTS SIGNAL.
C5 = IAC COIL "A" HI.
C6 = IAC COIL "A" LO.
C4 = IAC COIL "B" HI.
C3 = IAC COIL "B" LO.
ECM Wiring Diagram (Part 2 Of 4):
B8 = A/C SIGNAL.
A2 = CLUTCH CONTROL.
B1 = 12 VOLT.
C16 = 12 VOLT.
A1 = FUEL PUMP RELAY DRIVE (12 VOLT).
B2 = FUEL PUMP SIGNAL.
ECM Wiring Diagram (Part 3 Of 4):
A5 = SERVICE ENGINE SOON LAMP CONTROL.
C7 = HIGH GEAR SWITCH SIGNAL.
A7 = A/T TCC CONTROL GROUND.
A10 = VEHICLE SPEED SENSOR.
A4 = EGR SOLENOID (M/L).
A4 = EVRV SOLENOID (S/T).
B10 = PARK NEUTRAL SWITCH (A/T).
A6 = 12 VOLT IGNITION.
B7 = KNOCK RETARD SIGNAL (ESC).
ECM Wiring Diagram (Part 4 Of 4):
A6 = 12V IGNITION.
D16 = INJECTOR DRIVER.
D14 = INJECTOR DRIVER.
D4 = EST.
B5 = REFERENCE.
D5 = BYPASS.
B3 = REF. LOW.
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:
- • 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.