Auxiliary Water Pump Relay

This device is meant to run for roughly 8 minutes after the ignition is turned off.

Sometimes they work perfectly, sometimes they don't work at all others they run non stop.

The relay is found around the nearside of the vehicle, the relay is square and the bottom is round, the connector is covered by a rubber boot which is meant to seal against moisture, there is also a mounting bracket on the top of it.

The relay is meant to be mounted on the nearside inner wing just ahead of the aux relay/fuse box, in one of the round cut out holes, there should be a threaded clip there to accept a screw.

The relay however is not water tight, they get water in them and they run a tad hot as well.

The relay looks like this inside

This one came from the black exec/project Y and is in a bit of a state



this is my chamades





As you can see that relays top corner is not to healthy looking. That relay actually works fine.

I cleaned the relay casing up to remove the dirt and the mess at the top from corrosion, this relay when I bought the car was cable tied by the wire and danglinn down, so water must have got in then.

I then used the toothbrush again to clean the board, then a quite rinse with clean water (water will NOT damage PCB's if its pure water and dried off after) that cleaned it up a lot, the soldered joints have suffered so a dab with the soldering iron sorted them out.

Looks a lot better now and it does indeed shut off after 8 mins, used to run for 10.

The plug to the relay can also suffer. The plastic casing though can be popped open so the spade clips come out. So you can clean them up. If the connectors are to corroded then snip the wires and crimp on new spade clips and fit them back in the connector block.

The rubber boot that goes around the plug can be fitted a few ways, the correct way doesn't look right but it is. The gap in the 'T' is opposite to the horizontal spade terminal in the plug.

The relays can just die and they can melt, in these cases a new relay is needed, you should however make sure that the wiring and plug are ok as well.

On some cars the pump doesn't work, don't worry, the pump is a crap design and doesn't do much pumping, its a carbon copy of a turbocharger btw. Its there to in therory at least keep coolant flowing to prevent localised boiling in the head. It doesn't shift enough water for this to work properly but its nice to have it working and it does shift some coolant around. The impellar in it is rotated by magnetism, if theres any grit in it then the pump can stop.