LEMON Manuals: Even more car manuals for everyone
Home >> Isuzu >> 1996 >> Hombre S >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Emission Systems & Sub-Systems >> Miscellaneous Pcm Controls >> Tachometer Control Circuit Diagnosis

Tachometer Control Circuit Diagnosis

  1. Diagnose instrument cluster. See appropriate INSTRUMENT PANEL article in the ACCESSORIES & EQUIPMENT section. After diagnosis, go to next step.
  2. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in BASIC TESTING article. After performing OBD system check, go to next step.
  3. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using a DVOM, check voltage between tachometer control circuit at PCM harness connector terminal and ground. See WIRING DIAGRAMS section. Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage was not present, go to step 7).
  4. Set DVOM to 10-amp scale. Check current between tachometer control circuit and ground. Monitor reading for about 2 minutes. DVOM should read .05-1.50 amps. If reading is not as specified, go to next step. If reading is as specified, go to step 12).
  5. Disconnect instrument cluster, leaving PCM connector disconnected. Using DVOM, check voltage between tachometer control circuit and ground. DVOM should read zero volts. If voltage reading is as specified, go to step 15). If voltage reading is not as specified, go to next step.
  6. Locate and repair short to voltage in tachometer control circuit. After repairs, go to step 17).
  7. Check ignition feed fuse for instrument cluster. If fuse is blown, go to next step. If fuse is okay, go to step 9).
  8. Locate and repair short to ground in ignition feed circuit to instrument cluster. Replace fuse and go to step 17).
  9. Disconnect instrument cluster connector. Turn ignition on. Check voltage between ignition feed circuit for instrument cluster and ground. Battery voltage should be present. If battery voltage was not present, go to step 14). If battery voltage is present, go to next step.
  10. Check tachometer control circuit for an open or shorted circuit to ground. If circuit is open or shorted, go to step 17). If circuit was okay, go to next step.
  11. Check tachometer control circuit and ignition feed circuit for poor connection at instrument cluster and at PCM. If problem is present, repair as necessary and then go to step 17). If problem was not found, go to step 15).
  12. Turn ignition off. Reconnect PCM harness connector. Disconnect instrument cluster connector. Turn ignition on. Connect a test light between tachometer control circuit and ignition feed circuit at instrument panel harness connector. Using a scan tool, perform OUTPUTS TEST function to cycle tachometer control output light on and off. If test light flashes on and off, check for shorted component or circuit in the output driver circuit. Check for faulty instrument cluster. If test light does flash on and off, go to next step.
  13. Check tachometer control circuit for poor connection to PCM. Replace defective terminal and then go to step 17). If terminal is okay, go to step 16).
  14. Repair open in ignition feed circuit to instrument cluster. After repairs, go to step 17).
  15. Replace instrument cluster and then go to step 17).
  16. Replace PCM and then go to next step.
  17. Start engine and observe tachometer. If tachometer does not operate properly, diagnose instrument cluster. See appropriate INSTRUMENT PANEL article in the ACCESSORIES & EQUIPMENT section.
scientia non olet · About LEMON Manuals