From David Gans' liner notes to The Music Never Stopped: Roots of the Grateful Dead (1995, Shanachie Records):
Today, we think of Love Light as an R&B "oldie," but when Pigpen started singing this with the Dead back in 1967 it had only been out for a little more than five years... In the '60s, particularly, the Dead played a lot of R&B material that was "current."
The original of Turn On Your Love Light was recorded in Houston in the fall of 1961 by the great Memphis R&B singer Bobby "Blue" Bland. Raised on a cotton farm outside of Memphis, Bland gravitated toward music early in life and by his late teens, (the late '40s) he was a fixture in a popular local gospel group called The Miniatures. He moved into R&B in 1949 when he joined the Beale Streeters, which included Johnny Ace and B.B. King. King, in particular, would prove to be a major influence on Bland; the two have worked together often through the years.
...Turn on Your Love Light was written for Bland by the Blues Consolidated tour's trumpeter/arranger Joe Scott... The song made it up to #2 in early 1962....
Love Light became a show-stopper for Pigpen and the Dead almost as soon as it was introduced. It would often be stretched out to almost unbelievable lengths, with long, long passages of sizzling R&B jamming, short atomic drum breaks and Pigpen's frequently hilarious mid-song stories about his romantic conquests and/or misadventures. More often than not it occupied the show-ending slot, when the band could pour out whatever energy they still had and play sloppy and funky and have it be completely appropriate. When Pigpen stopped performing with the band in mid-'72 (he died a year later) the band retired the song. Then, at an impromptu gig in Amsterdam in 1981 the band fell into the song almost by accident and Weir gamely sang it. They played it twice in 1982—once backing up Boz Scaggs at a benefit concert, once backing Etta James at a Dead New Year's Eve show—and then Weir brought it back in earnest in the summer of '84. Though the modern versions lack both the punch and the exploratory wildness of their earlier flights on the song, Love Light is still occasionally a satisfying set-closer for the band.
Lyrics
only an approximation, as the song was so prone to improvised riffs
Without a warning, you broke my heart
You took it baby, tore it apart
And you left me sittin' in the dark, cryin'
You said your love for me was dyin'
Come on baby, baby please
I'm beggin' you baby, I'm on my knees
Turn on your light, let it shine on me
Turn on your love light, let it shine on me
Let it shine, shine, shine, let it shine
When I get a little lonely in the middle of the night
And I need you darling to make things all right
Come on baby, baby please
Come on baby, baby please
Turn on your light, let it shine on me
Turn on your love light, let it shine on me
Let it shine, shine, shine, let it shine
A little bit higher, a little higher (repeat)
Come on baby, baby please
I'm begging you baby, I'm down on my knees
Turn on your light, let it shine on me
Turn on your love light, let it shine on me
I feel all right, I feel all right (repeat and fade)
The Grateful Dead's best-known recording of "Love Light" is probably that on their "greatest hits" album, Grateful Dead/(The Best of) Skeletons From the Closet but I'm rather partial to the much more extended version on Live/Dead. All in all, a truly kickin' tune.