Section 24 (Instrument Panel): Testing: Tachometer

WARNING: This page is about a different car, the 1995 Pontiac Grand Am. However, it is still accessible from the selected car via links, so may be relevant.

Disconnect Electronic Ignition (EI) connector (V6) or Powertrain Control Module (ECM) connector C2 (4-cylinder). Plug Instrument Panel Tester (J 33431) into a wall outlet. Connect Harness Connector (J 33431-10) between tester and EI terminal "C" (White wire) or PCM connector C2 terminal B11 (White wire). Set tester controls to ON, 60 Hz, and 54 MPH.
If tachometer reads 1350 RPM (V6) or 1800 RPM (4-cylinder), check for clean and tight connections at EI or PCM. If connections are okay, replace EI or PCM. If tachometer does not read 1350 RPM (V6) or 1800 RPM (4-cylinder), check White wire for an open or short circuit to ground. If wire is okay, replace IPC.