The E36 Service Interval (SI) lights reset through the round 20-pin connector under the hood, NOT the odometer button — the trip-button trick belongs to the later E39/E46 and doesn't work here.
- With the ignition on and engine off, briefly ground the reset pin — a short ground resets OIL SERVICE, a longer hold resets INSPECTION
- Or use a Peake/reset dongle on the 20-pin connector (or the OBD-II port on late cars)
Separately, the cluster has a hidden self-test: hold the trip-odometer reset button in while you turn the ignition to position I or II and keep holding — the cluster runs a segment/LCD check and gauge sweep and steps through numbered tests with the same button.
Exact 20-pin SI-reset pin numbers vary by write-up, so verify against a Bentley or Peake pinout before you start grounding pins.