Tach Pulse (RPM Reference) Signal
WARNING: This page does not describe the selected car, but rather 39 other vehicles, including the 1992 Saturn SL2, 1992 Saturn SL1, 1992 Saturn SL, 1992 Saturn SC, and 1992 Pontiac Sunbird. However, it is still accessible from the selected car via links, so may be relevant.
Connect "Scan" tester to ALDL diagnostic connector. RPM should be indicated on tester when engine is cranked or running. Tach pulse (RPM reference) will be indicated as a voltage signal when a DVOM (with a minimum 10-megohm input impedance) is used to backprobe circuit No. 430 ECM terminal. For circuit and terminal reference, see appropriate schematic in NO START - ENGINE CRANKS OK in this article.