Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Wiper Woe's

Just to revive this thread and explain why Mark had this issue, I've discovered the following regarding later Lucas wiper stalk, Wehrle controlled wipe relay and wiper motor itself. This trio illustrated below were fitted to Classics from 2014 onwards and maybe earlier.





The wiper motor has the usual self parking mechanism where an integral changeover switch is operated by a cam on the drive wheel. This allows continued current to motor after wipers are turned off until the cam, coinciding with the wiper park position, throws the switch to ground the normally live side of the motor. This effects a short on the motor windings and with help from the back emf stops the motor dead so preventing overrun of park position. The motor has two field windings offering slow and fast continuous speeds selected by twisting end of stalk switch.

A dedicated six pin relay accepts a square wave on/off blip to a trigger on an integral IC which completes a circuit on the relay coil by grounding and so switches changeover contacts, timed to offer a slow speed single wipe from momentary downward operation of wiper stalk. Similar action by pulling stalk forwards operates screen washer which on release engages a second IC trigger timed to give three slow wipes (see first diagram below).

First twist position on end of stalk engages delayed wipe with each of four delay periods selected by inner knurled twist selector with longer downwards. I imagine each chosen delay is via capacitive circuits within wiper stalk providing chosen delays via stalk flying lead which connects and accepts delayed square wave to single wipe trigger on relay.

Note in each case after relay coil is de-energised or wipers turned off completely, the self parking mechanism takes over.

Apologies if above is not 100% accurate but some intuitive thought was used to fill in gaps where info not fully available.

The WEHRLE circuit diagram below illustrates much of above particularly the relay with dotted outline top right. Although the switch controls to the left are difficult to interpret the two triggers to relay I and 53c can be seen controlling the IC within relay.



A generic easier understood wiring diagram below using similar wiper relay generally illustrates above. Note although screen wash is controlled by isolated switch here it does integrate to offer timed wipes as with our Mogs. Relay triggers here are labelled I and T.

I had the original Landy ones on my car. Not the best! Replaced with the “modern” ones as advertised in Miscellany ( now also available from others, dealers). What a difference! Bought the 6” version. Just a bit of fiddling with the arms to get optimum sweep. Worth every penny, and about the same price as the Landy ones.

The blades you mean ? I have them on my Roadster & they are brilliant.

Definitely! Got to be one of the best upgrades.