Repair notes for the E39 windscreen wiper relay.
The relay is under the left hand pollen filter…
The filter housing is held at the front by a wire retainer clip, which secures the box to a bolt. Squeeze the legs and pull the clip forward.
The filter lid is retained by the front wire clip, and rear lugs.
Pull the front clip forward to release the lid, and lift the lid off.
Next, you need to remove the rubber seal from around the filter housing. Start by lifting the seal from the wing, where black goo sticks it to the car.
Having removed the rubber, undo the air intake pipe. This is the later clip, which just lifts off the pipe. The earlier version uses a slightly different arrangement, but it’s easy to figure out.
Next, undo the plug from in front of the housing, by squeezing the lugs top and bottom, and pulling out.
Now lift the forward edge of the filter, and remove it. The outer edge has a drain…
Which pokes into the wing slightly, so it needs some wiggling to remove.
Now you can see the electrical box. There is a sealing strip behind which needs to be removed to access the rear Allen screws.
Using a 10mm spanner, loosen but don’t remove, the bolt. The seal will now lift out.
Now remove the front and rear bolts from the cover. Rear shown below…
At last! The relay: A firm tug will release it from it’s mounting socket…
To remove the lid, use a small screwdriver and lever the case off.
Once the case is off, you can see the relay contacts. This is one of them:
To remove them, squeeze the contact and unhook the loop…
Below you can see a contact, and this is the bit which will be black and carbonized. This particular one isn’t too bad.
But this one was: Either bin it and fit a new one, or file the carbon off it, and apply a small blob of solder. File the blob to a suitable shape and rebuild the relay.
Now it’s time to re-assemble the car! Start be refitting the relay – it only goes in one way, so be sure to orientate it correctly.
Before refitting the electrical box lid, check the weather seal is correctly seated:
Screw the lid back on, being careful not to over-tighten or you may knacker the nuts in the base! Now refit the wiper cavity weather seal. Start by sliding it under the wiper motor…
And over the securing bolt. Tighten the bolt.
Next up is the pollen filter, but before you refit it, check the drains are clear. The side drain:
And the front drain:
Now refit the filter making sure to ease the side drain into the wing, and align the rear mounts over the loops:
Refit the weather seal:
Reconnect the electrical plug, and refit the forward retaining clip. Next the air intake duct, and again the older variety use a different method.
Lastly refit the lid and secure with the forward wire clip:
Enjoy another 5 years of trouble free rain sensing wipers!