I was out today in the D2 and it was piddling down with rain. Put on the rear wiper and then noticed it had stopped after a few sweeps. Last year I'd had a similar problem and stripped the wiper motor, checked it, greased it and hey presto it worked fine. I never found out what was wrong with it.

So this evening it loaded the RAVE disc into the l/top and looked at the wiring diagrams, checked out relay was clicking OK, front wipers were working fine. So went outside and looked at the blade and moved it by hand a tiny bit. Jumped into the truck and turned on the ignition pressed the wiper buttons, first the wiper only and then the wipe/wash, all working fine. So stuck the truck into reverse and again the wiper was working OK. I had replaced the reversing lamps recently with lamps that bleep also (the French always obliviously walk behind you when you are reversing - I get bored scraping them off my tires) so I thought that may have interfered with the wiper sequence as they are connected in some way (lord knows how). Anyways, I assume it must have been electronic gremlins at work as the rear wiper system seems overly complex (blame BMW) for what it does. I also found out what IDM means................'Intelligent Driver Module'............now who said LR drivers were intelligent, stupid.....yes,.........masochistic.........yes, but not sexual masochism

 

Well I wouldn't ask a Frenchman for backup help right now , But my rear wiper forgets to wipe occasionally Turned it on and off a few times and it worked. I had just added the towing electric module. Maybe similar ?? might need to find ecm and clean contacts if its intermittent.

 

Not sure if I'm reading your post or your problems correctly, but I believe your wiper is working perfectly fine and you're looking waaaaaaaaaaaaaaaay too far into things, at least as far as the reverse circuitry / bulbs impacting wiper performance.

I've found when diagnosing cars, to always start with the most simple things at this point.. THEN get more complicated if you need to. Never just jump in thinking it's a buried circuit issue or something. I do a lot of electrical diagnostic stuff at work on vehicles and motorcycles and the techs drive me INSANE sometimes. Half the time it's a bad ground, loose bolt, broken wire etc.




IN ANY EVENT

I believe the rear wiper is INCAPABLE of running continuously during forward motion/driving, it's purely an intermittent wiper system, probably to reduce driver distraction.

Activating the wiper for the first time should initiate three swipes before it resumes a program based on the FRONT wiper settings.

I think the way I usually have mine set up (speed dependent intermittent for front wipers) every OTHER front swipe will activate the rear swipe. I'm not sure if this ratio is followed for the faster intermittent settings. Once the fronts are "steady" slow/med/fast, the rear wiper only swipes every few seconds but again, I think there is a steady ratio chosen by the module, since the front and rear are activated at the same time when it does decide to use the rear.

When in reverse, the module automatically activates the rear wiper steady since you're already looking out the back window so distractions aren't an issue and you may need to clear mud/dust off quicker, or since vehicle would now have rain hitting the face of the rear windshield instead of away during fwd. motion. This is completely normal.

Take some time to look for the patterns and you'll realize some Brit spent a lot of time programming the thing to do what it does lol!

FWIW my Range Rover Sport is programmed almost exactly the same way, although they did add a second intermittent dial on the stick for the rear but it still won't go continuously. The aerodynamics on the sport make the rear a magnet for dust, dirt, mud, and road spray so I wish the thing would wipe faster actually. Especially with road spray, it gets covered between wipes (the Discovery in contrast stays nearly clear!)