Test B: Malfunction In Tachometer
WARNING: This page is about a different car, the 2003 Lexus ES 300 and 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
- Read the value of the hand-held tester (TACH).
- Check the output of the ECM. See Fig 1. Connect the hand-held tester to the DLC3. See Figure. Turn the ignition switch to ON and push the hand-held tester main switch to ON. Select the item ENGINE SPD in the DATA LIST and read it's value displayed on the hand-held tester.
- It is OK if there is almost no difference in the displayed engine RPM value. If the results are OK, go to the next step. If the results are not OK, go to appropriate SELF-DIAGNOSTICS - ES300 article under FAULT ISOLATION in ENGINE PERFORMANCE.
- Check the combination meter assembly:
- Check the input signal of the waveform using an oscilloscope. Remove the combination meter assembly with the connectors still connected. Connect the oscilloscope to the terminals No. C7-31 and C7-1 of the combination meter assembly. See Figure. Start the engine. Check the signal waveform. See Fig 2. See TERMINALS C7-31 & C7-1 SIGNAL WAVEFORM table.TERMINALS C7-31 & C7-1 SIGNAL WAVEFORM
Item Contents Tool Setting 5 V/ DIV, 20 ms/ DV Vehicle Condition Engine Idle Speed - If the results are OK, check and replace the combination meter assembly. See COMBINATION METER SAFETY PAD SUB-ASSEMBLY under REMOVAL & INSTALLATION. If the results are not OK, repair or replace the harness or connector.
- Check the input signal of the waveform using an oscilloscope. Remove the combination meter assembly with the connectors still connected. Connect the oscilloscope to the terminals No. C7-31 and C7-1 of the combination meter assembly. See Figure. Start the engine. Check the signal waveform. See Fig 2. See TERMINALS C7-31 & C7-1 SIGNAL WAVEFORM table.