If you are familiar with Chris Rea you'll identify the sound of windscreen wipers clearing the windscreen of a car in the dark and moody opening of his track 'Road to Hell'. Windscreen wipers working as they should despite the slightly depressing theme! Unfortunately for BART this was not the case, not even close. The wipers barely moved, stuttering slowly across the windscreen as if trying to clear away treacle or some other thick and gooey substance, switching to high speed made no difference.
With the UK x1/9 Owners Club annual event due to take place in Wales this coming September I thought it was time to address the problem.
Like the headlights, the wiper power feeds run through multiple switches and connections and as I discovered with the lights the combined losses of the wiring caused a drop of 2.5v. The solution was to install some make and break relays to switch a high current feed directly from the battery taking the load off the original wiring and connectors.
BART has two speed wipers so I ordered 2 relays from 12voltplanet.co.uk plus relay holders and a fuse holder. These all clip together making for a neat installation.
Fuse Holder: https://www.12voltplanet.co.uk/standard-blade-fuse-holder-with-terminals.html
Relay Holder: https://www.12voltplanet.co.uk/standard-mini-relay-socket-with-terminals.html
The relays where 40amp 5 pin change over relays or you can use 4 pin make and break relays, either will work. All the wiring and fuse where 20amp rated.
I started by removing the drivers side scuttle grill and separating the wiper motor connector. You need to locate the Grey (high speed) and Red (low speed) wires and remove the connectors from the plug (female connectors) by sliding a very fine screwdriver into the small square cutout of each terminal. These will now control a relay each to switch a fused feed from the battery.
I used a spare two terminal connector to connect and extend the Grey and Red wires into the Frunk via the bulkhead wiring grommet connecting up to the relay block on pin 86 of the relay. Pin 85 of the relay is the ground pin and I daisy chain connected them together and found an earth on the bulkhead grommet studs.
A feed then needs to be taken from the battery and connected via the fuse block to pin 30 on each fuse, again I daisy chained the connection. Pin 87 (normally open) from each relay then becomes the output (high current feed) from the relays connected back to the wiper motor using the existing OEM connector.
This shows the earth tag to Pin85, the relay block connected together, the battery feed and wiring to and from the wiper motor connector.
I finished off with some spiral wiring wrap to neaten everything up. The result...Wow, just like the headlights the difference was night and day. Even on a dry screen the wipers move quickly and smoothly traversing without stopping or stuttering, result!
Wiring diagram (click to expand):
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