LEMON Manuals: Even more car manuals for everyone
Home >> Cadillac >> 1994 >> DeVille Base >> Repair and Diagnosis >> Accessories & Equipment >> Gauges & Instrument Panels >> Component Testing >> IPC Tests >> Tachometer Inoperative/Inaccurate (Analog Cluster)

Tachometer Inoperative/Inaccurate (Analog Cluster)

  1. Start engine and note tachometer reading. If tachometer is inoperative, go to step 5). If tachometer functions, go to next step.
  2. Enter self-diagnostics. See ENTERING SELF-DIAGNOSTICS  under SELF-DIAGNOSTICS. Select PCM parameter PD11 (RPM reading). Compare vehicle tachometer reading and PD11 reading while varying engine speed. If readings vary by more than 200 RPM, go to next step. If the 2 readings are always within 200 RPM of each other, go to step 4).
  3. Check IPC connector terminal B1 for proper terminal contact. See Figure . If terminal contact is okay, replace IPC. See INSTRUMENT PANEL CLUSTER  under REMOVAL & INSTALLATION.
  4. Ensure good terminal contact at all electrical connections. While wriggling harness, attempt to duplicate conditions under which failure occurred. If intermittent fluctuations occur, check for proper routing of White wire between IPC and ignition control module (4.6L) or distributor (4.9L).
  5. With engine running, backprobe IPC connector terminal B1 to ground with a voltmeter set to AC voltage. If voltage is greater than 8 volts AC and voltage changes with RPM fluctuations, go to next step. If voltage is less than 8 volts AC and/or voltage does not change with RPM fluctuation, go to step 7).
  6. Ensure proper terminal contact at IPC connector terminal B1 (White wire). If terminal contact is okay, replace IPC. See INSTRUMENT PANEL CLUSTER  under REMOVAL & INSTALLATION.
  7. Turn ignition off. Disconnect Black IPC connector. Start engine. With a voltmeter on AC setting, measure voltage between IPC connector terminal B1 (White wire) and ground.
  8. If voltage is less than 8 volts AC and/or voltage does not change with RPM fluctuation, go to next step. If voltage is greater than 8 volts AC and voltage changes with RPM fluctuations, repair White wire between IPC and ignition control module (4.6L) or distributor (4.9L).
  9. Ensure proper terminal contact at IPC terminal B1. If terminal contact is okay, replace IPC. See INSTRUMENT PANEL CLUSTER  under REMOVAL & INSTALLATION.
scientia non olet · About LEMON Manuals