GMC Sierra Automatic Transmission Indicator Bulb Size

GMC Sierra automatic transmission indicator bulb uses a 161 size bulb for this component. The replacement chart covers vehicle production spanning 1999 to 2006.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Type	Shop
1999-2006	161	Check Price

Bulb Specifications

Description	Type	Shop
ANSI standard (US & Canada). Miniature wedge bulb (T10). 12V, 1W.	161	Check Price

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Additional Notes

The 161 bulb is the sole automatic transmission indicator bulb size listed for the GMC Sierra across the 1999-2006 model years.
The 161 is an ANSI-standardized bulb type, meaning its specifications are governed by a recognized North American standard shared across the United States and Canada.
The bulb uses a T10 miniature wedge base, a base style that requires no locking tabs or twist motion for installation, relying instead on friction from the socket walls to hold the bulb in place.
Operating at 12 volts and 1 watt, the 161 is a low-power bulb suited for small indicator and illumination roles rather than high-output lighting functions.
The T10 wedge form factor is widely used across many vehicle makes and models, which means the 161 is a broadly available bulb size in the automotive aftermarket.
Although T10 is a common base type, wattage and voltage ratings still govern compatibility. A T10 bulb with different electrical ratings would not be a direct equivalent to the 161.