Following tjts1's comment, I can testify my very-early 1996 E300D uses the same pre-glow relay as my 1995 (W124) version of this same car. This part is 015-545-30-32 and has no connections to the CAN bus because Mercedes introduced it gradually during the 1996 model number and my car was thankfully too early. By 1998 there was definitely a completely different relay in use; the question then is where did 1997 fall during this change?

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .343,000 miles Wife's car
2005 E320 CDI . . 148,000 miles My car
Santa Rosa population 177,300 (2026 projected)
Total. . . . . . . . . . . . 668,300
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970