4-Pin 15487756 GT Series Waterproof Connector – Ignition Coil & O2 Sensor Buick Chevrolet

Direct-fit replacement for GM OEM part number 15487756, a 4-pin waterproof GT (Global Terminal) series connector used for ignition coil harness connections and oxygen sensor circuits on Buick and Chevrolet vehicles. The GT series is GM's standardized connector family for high-temperature engine bay applications, designed to withstand the thermal cycling and vibration of ignition coil mounting locations.

Key Specifications

• OEM Part Number: 15487756
• Pin Count: 4
• Gender: Female socket (with wire)
• Series: GT (Global Terminal) series
• Wire Gauge: 18 AWG (0.5 mm²)
• Wire Length: 5.5 inches (140 mm)
• Waterproof Rating: IP68
• Housing Material: PA66 glass-filled nylon (high-temp rated)
• Terminal Material: Copper alloy, tin-plated
• Operating Temperature: -40°C to +150°C

Compatible Vehicles & Applications

• Buick: LaCrosse, Regal, Enclave – 3.6L V6 ignition coil harness
• Chevrolet: Malibu, Equinox, Traverse – 2.4L and 3.6L ignition coil connectors
• GMC: Acadia, Terrain – shared platform ignition harness
• O2 sensor application: 4-pin wideband oxygen sensor harness on GM 3.6L platforms
• Cross-reference: Verify OEM part number 15487756 before ordering

Ignition Coil Connector Failure – Why It Happens

Ignition coil connectors are subjected to extreme conditions: temperatures up to 150°C, high-voltage inductive spikes from the coil primary circuit, and constant vibration. The 15487756 connector fails due to:

• Terminal fretting corrosion from vibration – causes intermittent misfire
• Heat-induced insulation cracking – exposes wire conductors to short circuit risk
• Moisture ingress after seal degradation – causes coil primary circuit faults

Fault Codes Linked to 15487756 Connector Failure

• P0300–P0306 – Random/Multiple Cylinder Misfire (most common)
• P0351–P0356 – Ignition Coil A–F Primary/Secondary Circuit
• P0136 / P0156 – O2 Sensor Circuit (Bank 1/2, Sensor 2) when used for O2 sensor application

Frequently Asked Questions

Q: Can a bad ignition coil connector cause a misfire?
A: Yes. A corroded or loose 15487756 connector interrupts the coil primary circuit, preventing the coil from firing. This produces a single-cylinder misfire (P030X) identical to a failed coil. Always inspect and test the connector before replacing the ignition coil – coils cost significantly more than connectors.

Q: How do I test the ignition coil connector?
A: With the connector disconnected, measure resistance between the terminal contacts – any reading above 0.3Ω indicates corrosion. Visually inspect for green oxidation, bent pins, or cracked housing. Apply dielectric grease to terminals before reconnecting.

Q: What crimping tool is needed for GT series terminals?
A: Use the Kent-Moore J-38125-8 or equivalent ratchet crimper rated for the GT series terminal wire gauge (18 AWG / 0.5 mm²).

Package Contents

1 × 4-Pin Female Socket Connector (15487756) with 18 AWG wire and terminal inserts