mdweiss

So Ive searched and found nothing about a factory intercooler water pump relay. I cant imagine Mercedes not using a relay to control something with such a high amperage.

what i want to do is find it, and change the trigger from the ecu controlled one to an ignition constant trigger. it should be less work and easier to set back to stock than completely rewiring it with a new relay.

if anyone has any info of where it is, if there is one please post

chiromikey

against popular misconception, there's no need to rewire your i/c pump. once the car is up to normal operating temp (and unless there is something wrong with the pump itself), the ecu already runs the pump constantly.

mdweiss

I have a trunk mount reservoir and i don't see the pump running too often. i also would like to be able to run the pump while the car is not running to cool the water.

chiromikey

that's strange...i also have a reservoir set-up and have my pumps/fans wired to a 3way switch (off/ecu controlled, pumps on, pumps and fans on). when allowing the ecu to control the pumps they're on all the time except initial start up. we both have 03's but maybe my car is different.

mdweiss

ya idk, i have a meziere pump installed as well so the pump is fine. At the track with circulating ice it would be nice to just turn the ignition on.

so back to the question...is there a relay ?

mdweiss

my car has also been reflashed with dealer updates which I believe run the pump less because of the high failure rate of the stock pump

chiromikey

interesting and highly likely knowing mb's track record.

Yacht Master

To answer your question, no stand alone relay, it is switched by the ECU, so be careful not to overload that circuit. Chiromikey's 3 position switch is the way to go.

mdweiss

got it thanks!!

JoeNobody

This thread is super old, but just for the record the pump IS controlled by a relay in the rear SAM.