Hi Scotty! I have a 1988 Toyota Corolla 1 .6L carbureted 3 speed automatic with around 190,000 miles. When the car is idling at a stop, the idle speed drops if the brakes are applied, if the steering wheel is turned, or if accessories like the fan/lights/defrost are on. I've replaced my brake booster with no change or improvement. My battery is heavy duty and relatively new. Any idea about the cause? I have found a Toyota forum online reporting a similar issue on a Toyota truck from this era but with no resolution. Thank you!
https://yotatech.com/forums/f116/idle-drop-when-brakes-applied-278681/
Load test your alternator. If it checks out ok, your power streering pump is on its way out.
It checks out okay. But how could the power steering pump be responsible for the idle drops on the brakes or electrical gadgets? Just doesn't make sense.
When I turn the wheel there's no whining or groaning or squealing. The wheel isn't slow to respond or stiff. The steering is totally normal.
If the power steering is weak, it needs more power to function and puts load on the alternator.
Makes sense. Well I just load tested my alternator and it was well within spec @ 14.24 V. Maybe it's the throttle positioner system. I know it's supposed to increase idle RPM when power steering fluid pressure exceeds a certain value or when a large electrical load is placed on the system. I need a Toyota carburetor expert (if I can find one anymore lol). Thanks.