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 MANUALSGMC1995RALLY G2500, 4.3 ZREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCEENGINE CONTROLS - ADJUSTMENTS - 4.3L.IGNITION TIMING4.3L WITH DISTRIBUTOR
1995 GMC Rally G2500, 4.3 Z
4.3L With Distributor
1995 GMC Rally G2500, 4.3 ZSECTION 4.3L With Distributor
- Set parking brake, block drive wheels and place transmission in Neutral or Park. Warm engine to normal operating temperature. Turn A/C off (if equipped). Ensure Malfunction Indicator Light (MIL) is off.
- Disconnect Tan/Black Electronic Spark Timing (EST) by-pass connector wire. DO NOT disconnect 4-wire connector at distributor.
- On models where engine computer is located underhood, on right fenderwell, by-pass connector which is a single Tan/Black wire, breaks out of wiring harness near engine computer harness connectors.
- On models where engine computer is located in passenger compartment under right side of instrument panel, by-pass connector which is a single Tan/Black wire, breaks out of wiring harness where heater box and carpet meet on passenger side floor. Pull back carpet to expose single Tan/Black wire and connector on outside of control module harness.
- On all models, connect timing light to No. 1 spark plug wire. Check timing and adjust if necessary. See IGNITION TIMING . Reconnect EST by-pass connector. Clear Diagnostic Trouble Code (DTC).
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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.