Steering Control Module: Testing and Inspection

1. Raise and support vehicle.
2. On ES 250 models, remove safety pad as outlined under DASH PANEL.
3. On LS 400 models, remove instrument panel No. 1 as outlined under DASH PANEL.
4. On all models, start engine.

Fig. 21 Power Steering ECU Inspection:

5. Measure voltage of ECU using a suitable voltmeter between ECU terminals SOL - and GND, Fig. 21.
6. Standard voltage is .32-.44 volts on ES 250 and LS 400, .43-.56 volts on ES 300 and .3-.5 volts on SC 300 and SC 400.
7. Place transmission in gear and while running at 37 mph, measure voltage between ECU terminals SOL - and GND.
8. Standard voltage is voltage measured in step 5 minus .04-.18 volts on ES 250 and LS 400, .08-.22 volts on ES 300, .05-.18 volts on SC 300 and .07-.2 volts on SC 400. If sum equals zero volts, try another ECU.