124 wiper - intermittent is intermittent

[lrg]

1987 300d turbo

My wipers are suddenly intermittent when on the intermittent setting. Sometimes they work normally other times they'll stop at various points and then restart by themselves. The full time speeds are completely normal and the wipers will park normally when I turn them off. The problem doesn't seem to be affected by wiggling the switch so I suspect a faulty relay or possibly bad contacts or circuit in the motor. So before I tackle this some questions:

1. Anyone had this problem? If so what was the fix?

2. Where is the wiper relay on the 124?

3. Where does the circuit/control that makes the wiper intermittent reside? In the motor or somewhere else?

Thanks.

[babymog]

I think, am not sure, that it is the convenience module, a long relay-looking box dead-center in the relay box (back half of the fusebox, remove four screws) PN: 201 821 00 47 or equivalent.

[sixto]

Very close. ETM says it's the N10 combination relay. Most forward of the center row of relays. Looks about 2.5x the length of a typical relay.

Sixto
87 300D

[babymog]

That's the one. Fortunately, the same one is used in 124, 126, and 201. Easy to find used.

[lrg]

Thanks for the info. I think I'll try to take this one apart and clean the contacts and see what happens. I'll report back with the results.

[lrg]

I found the relay, took the cover off and carefully cleaned the contacts on the relays inside(there were three). The wipers are still stopping off and on mid-swipe on the intermittent setting. Since the wipers work fine when set to the full time settings I have to think the motor and park mechanism is fine. Looks like the relay needs replacing.

[Graplr]

On my 126, the hi and lo wipers worked fine when I bought it. The intermittent switch did not work. I took out the relay and banged it on the table a few times. Then the intermittent wipers worked the same as lo for awhile and then stopped again. I bought a new relay. Now all 3 settings work as they should.

[Jeremy5848]

Right, it may be the switch. If you can trace the wiring from the combination switch to a connector, you could unplug it and try using jumpers to activate the intermittent function. If it works properly with jumpers then you know it is the combination switch. If it still doesn't work then you know it's the relay.

OK, the ETM says look for X63, a 14-pin plug/socket located "behind left side of dash panel, left of cruise control amplifier." In X63, pin 1 (black wire) is "normal speed" (of wiper), pin 13 (blue wire) is high speed, pins 9 (brown) and/or 14 (green) are intermittent. Pin 11 (black/violet) is the hot lead. Looks like you should jumper pin 11 to pins 9 and/or 14 to do the intermittent wiping.

Sixto, take a look at ETM page 154, what pin or pins look right for intermittent? Not sure whether it's 9 or 14 or both. Looks like pin 14 for sure and maybe pin 9 also – what do you think?

Jeremy

[sixto]

Looking at page 159 of my ETM, pin 14 is the trigger for the relay to operate in intermittent mode vs pin 10 which is the trigger for 3 wipes to accompany the washers. What I understand of pin 9 is it's the power from the relay through the switch to pulse normal speed. The relay doesn't communicate directly with the motor as far as intermittent and washer modes are concerned. I don't know what the PARK-RUN switch to the right of the motor does.

To take the switch out of the loop, you'd have to jumper 11 and 14 to put the relay in intermittent mode and 9 and 12 so the timed pulse gets to the wiper motor. Or jump 11 and 14 and see if you get a pulse every 4 seconds from 9.

Sixto
87 300D

[lrg]

Well I found the answer and it wasn't what I expected. I replaced the multifunction relay as based on my searches I was pretty sure that was the problem. Unfortunately not in this case. The problem was dirty contacts on the switch at the stalk. I had mentally ruled that out because when I wiggled the stalk it didn't make the wipers move from their mid-stroke position but after I replaced the MFR and still had a problem I figured I'd better take a closer look at the switch. I pryed the end cap off and carefully took the switch apart. The contacts looked pretty good but not particularly clean and shinny. Since I had everything apart it made sense to carefully clean and buff the contacts. Low and behold the problem went away. I'm not quite sure what the details of the electrics are behind this but apparently the switch on the stalk has to be firmly connected on the intermittent setting or else it will stall the wiper mid-stroke. I assumed the wiper motor was OK because both the full on speeds were working fine and the wiper parked as it should from those speeds. Since my problem was only on the intermittent setting it seemed it had to be the MF Relay or the switch. I wiggled the switch thinking if I had a bad connection the wiper would move but it didn't. I guess the moral of the story is if you have a problem with your intermittent setting clean the contacts on the switch at the end of the left side stalk first before you replace the MFR.

Thanks everyone for your help.

[sixto]

I'm glad that had an easy ending. I just replaced my turn signal switch (remove airbag, steering wheel, lower dash cover...) because headlight flash wouldn't work but high beam did. I hope intermittent wipers works

Sixto
87 300D

[lrg]

Sixto - The good news is that if you need to access the wiper switch it's all at the end of the stalk. Just pry the end cap off and slide the cover toward the steering column and the switch is exposed. No need to repeat the disassembly of the wheel and lower dash. If the stalk assembly is new I doubt you'll have any problems.

[sixto]

I hope it works because I installed a used switch

Sixto
87 300D