Tachometer Test
- Turn ignition off. Disconnect instrument cluster 16-pin connector. Connect DVOM between connector terminal No. 13 (Black wire) and ground. Measure resistance. If resistance is less than 0.3 ohm, go to next step. If resistance is more than 0.3 ohm, repair open in Black wire.
- Disconnect engine control module connector. Connector is 24-pin on Federal models, or 22-pin on California models. Disconnect noise suppression filter connector. Connect DVOM between noise filter connector Brown wire terminal and 13-pin instrument cluster connector Brown wire terminal. Measure resistance. If resistance is less than 0.5 ohm, go to next step. If resistance is more than 0.5 ohm, repair open in Brown wire.
- Disconnect ignition coil connector. Connect DVOM between coil connector Brown/White wire terminal and noise filter connector Brown/White wire terminal. Measure resistance. If resistance is less than 0.3 ohm, go to next step. If resistance is more than 0.3 ohm, repair open in Brown/White wire.
- Reconnect all connectors and start engine. Connect fused jumper between noise suppression filter connector Brown and Brown/White wire terminals. If tachometer now displays engine RPM, go to next step. If tachometer still does not display correct RPM, check instrument cluster printed circuit for cracks or poor connections. If printed circuit is okay, replace tachometer.
- Turn ignition off. Disconnect noise suppression filter. Using test light, backprobe noise filter connector terminal No. 1 (Black wire on Calif. models, Black/Green wire on Federal models) to battery power. If test light does not come on, repair open in Black or Black/Green wire between filter and ground connection. If test light comes on, repair open in Black or Black/Green wire between noise filter and splice. If wire is okay, replace noise suppression filter.