Quote:
Originally Posted by bagpiperse
I am new to working on cars, but it looks like the relay is not sending power to the pump. I read somewhere that there is an engine sensor that somehow activates the relay through the ECU (??).
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One of the posts above references the engine temperature sensor. Remember that the ECU commands the SAI pump on at cold engine start. If the engine temp sensor is failed then the ECU might not ever think that the engine temp is cold and therefore, the ECU might never command the SAI pump on.
The engine temp sensor sends its signal directly to the ECU and the ECU commands on the SAI pump via a relay.
A relay is simply a component that allows a low power signal to send high power to a device. Relays allow most of the electrical system to be low power (and thus smaller and less costly). What this means is that when the ECU commands the SAI pump on, the ECU sends a low power signal to the relay which then sends (or relays) high power to the SAI pump.
To determine if this is indeed an "upstream" cause, check the temp sensor, ECU, relay, and associated wiring to ensure that they are all working properly.
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