240d wipers won't stop

[sides]

Hi all,

The windshield wipers on my '74 240d suddenly seem to have a mind of their own. Sometimes they work fine, other times they come on and I can't turn them off. When this happens I'm also unable to change the speed - they're stuck in the middle setting. Really annoying. I assume it's a switch issue. Is the solution to replace the entire wiper/turn signal arm from the steering column? Or is there a switch inside the arm or somewhere else that I need to replace?

Thanks,
Brian

[daidnik]

I'm not sure which switch you have. Some had a metal block structure for the cam system and others have a plastic setup. This will be visible if you remove the rubber cover from the steering column cutout that the stalk come thru.

Back to opening up the switch. First you remove the switch from the column by removing the two screws fixing the switch to the column. Remove the knee bolster cover under the driver's side dash and unplug the connector for the switch. Fish the connector out thru the column as you pull the switch. You may have to finagle a bit, but there is just enough clearance to get that connector thru and out.

With the switch out and on the bench, look closely at the squared end of the wiper switch. You will see that there is a very small (~1mm) roll pin thru that squared end. Push that pin out with small drill blank or pin of some sort, but it's got to be smaller than the hole (it's small). Once the roll pin is out the squared end will slide off and you will see the wiper switch and the contacts, etc. as well as the speed switch. You'll probably be able to figure out what's wrong visually. If not, then you'll have to use a multimeter as well.

Be carefull not to lose any springs from that assy. There are at least two in the end; one for the pushing on the end and one for the rocker speed switch.

New turn signal switches range around $200-$250.

[sides]

Thanks so much for the detailed info. It will probably be tomorrow before I can get into it but I'll let you know my progress. Does anyone happen to have any pictures? Thanks, BS

[tram]

If you want to verify the switch for sure, find out where the stalk unplugs to the left of the steering column. Next time it does it, pull over, unplug the connector and see if the wipers stop. Then plug it back in and see what happens.

Keep in mind that the plug you unplug also controls turn signals.

[mercmad6.3]

Just drive on rainy days.

[250 Coupe]

It might be what I call the park switch in the wiper motor.

If the wipers aren't in the park position when you turn the switch off, something needs to supply power to get them there. That's the job of the park switch. It's also used by the intermittent wiper circuit. The timer closes a relay, supplying power to the wiper motor just long enough to get it off the switch then relies on the switch to finish the cycle.

My '83 Mazda 626 would do the same thing, hit a bump or use the wipers then turn them off and they would go for a while before stopping. I don't remember the details 25 years on but something plastic under the round cover on the motor broke or corroded and was not that hard to fix.

Michael

[sides]

I played with the switch, took it out and inspected it, it seems to work just fine. Couldn't get it to not work. So it may very well be corrosion in the wiper motor, or the park switch. I cleaned all that up with electronic cleaner and a toothbrush, sealed the motor cover back up. To be continued.

[Tomguy]

If your 240 is like my 108, it could be a stuck switch in the foot pedal for the washer. Try some contact cleaner in it or just disconnect it.

[250 Coupe]

I forgot about the foot switch. It's more likely to be the problem than the park switch.

Michael

[sides]

Hi all, thanks so much for your help and ideas. I did disconnect the foot switch and that stopped the problem. I'm going to go through it with contact cleaner and see if I can reconnect it. But at least the wipers work well right now, so thanks again!

Brian