Test G: Tachometer Inaccurate
- With ignition in OFF position, verify instrument cluster connectors are secure. Remove instrument cluster and leave cluster connected. See INSTRUMENT CLUSTER
under REMOVAL & INSTALLATION. With ignition ON and engine running, verify voltage on terminal No. 6 (Green/White wire) of instrument cluster connector C268 on back of instrument cluster at indicated engine speeds. See Figure
- Figure
. See the TACHOMETER SIGNAL VOLTAGES
table. If voltages are correct, go to next step. If voltage readings are not correct, refer to appropriate TESTS W/CODES
article in the ENGINE PERFORMANCE section, for further information on diagnosing possible VSS or PCM concern.TACHOMETER SIGNAL VOLTAGES
Engine Speed (RPM) Voltage 1000 1.69 1500 2.64 2000 3.44 2500 4.50 3000 5.22 - Turn ignition off. Remove instrument cluster and disconnect all cluster connectors. Measure resistance between tachometer terminals on back of instrument cluster and instrument cluster harness connector C268 as specified. See Figure - Figure . See PRINTED CIRCUIT TESTING table. If all resistance measurements are less than 5 ohms, replace tachometer. If all resistance measurements are not less than 5 ohms, replace instrument cluster printed circuit. See PRINTED CIRCUIT under REMOVAL & INSTALLATION.
PRINTED CIRCUIT TESTING
| Tachometer Terminal | Cluster C268 Terminal |
|---|---|
| "B" | 2 |
| "G" | 5 |
| "S" | 6 |