The BMW 750iL brake light utilizes P21/5W and P21W bulb sizes for the rear lighting system. Data for the specified components covers the time range from 1988 through 2001.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The BMW 750iL brake light specifications cover model years 1988-2001, with two distinct bulb types used across that span depending on the year and light position.
P21W is the more widely used bulb type in these specifications, appearing across brake and center high mount stop light positions for the majority of the model years listed.
The P21W is a single-filament signalling bulb operating at 12V with a 21W output, fitted with a BA15s bayonet base, and produced to ECE standards for use in European and worldwide markets.
The P21/5W is a dual-filament signalling bulb operating at 12V with a 21W/5W output, fitted with a BAY15d bayonet base, also produced to ECE standards.
The BA15s base of the P21W and the BAY15d base of the P21/5W are physically distinct, as the BAY15d features offset pins to prevent incorrect installation, making the two bulbs non-interchangeable despite their similar appearance.
For the BMW 750iL, the brake light position uses P21W for model years 1988-1998 and transitions to P21/5W for model years 1999-2001.
The dual-filament design of the P21/5W allows a single bulb to serve two lighting functions simultaneously, which is why it is commonly used in combined brake and tail light assemblies.
The center high mount stop light on the BMW 750iL uses P21W across all listed model years, 1988-2001, with no variation in bulb type for that position.
Because the brake light position for 1999-2001 uses P21/5W while the center high mount stop light for the same years uses P21W, the two positions require different bulbs and are not interchangeable with each other during those years.
Substituting a P21W in place of a P21/5W in the brake light position on 1999-2001 models would result in the loss of one filament's function, as the single-filament P21W cannot replicate the dual-filament behavior of the P21/5W.