Early C4's had relays, located on LH side front under the headlight near the Vac tank.
From 88 (I tink) they went to electronic module, located in same position as the relays.
Easiest way to tell, are the wires into the H'light motors - three (3) for relay and two (2) for electronic module.
The electronic cct uses "current sensing" - ie. The cct is activated, applies juice to the motors, drives HL's up, when they hit the "N stop" the motors stall causing the current to peak (overload situation) and the cct senses this and cuts off. Same when HL's switched off, except now the current is reversed, drives HL's down.
I think there is also a built in timer cct, which also cuts it off if the gears or plastic drive slugs in the gearbox are shot.
I have an Electrical Ccts supplement which covers 84 thru 87E, my 87 is late and has the 88 onward electronic style cct (not covered).
I have seen HL's with striped drive gears and or friction slugs kapput.
Crook slugs wont drive up/down, or drop or droop.
I think Sabre sent me a cct diagram for 88/89 but I dont think it had an expansion of the cct inside the module, cant remember.
I would like to look inside one of these modules !!!!!!!!!......
