Author Topic: wipers and dash lights don't work too well... how do I fix them?  (Read 3325 times)

13B

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Ok for starters my wipers don't work well on my 450SE.  Intermittent works, slow speed doesn't work, and hi speed works but if i switch them off mid-wipe they won't park back down.  Where are the relays for these functions located?

Also my dash lights don't work - any pointers where to start looking for a problem related to them?

Question - in my fusebox there are four relays - what do they relate to?

I.
450SEL 6.9 #5440 = V MB 690 , 450SE # 43094 = 02010 H , 190E/turbo # 31548 = AOH 68K

TJ 450

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The wiper relay is not the small cube type, but a much larger black one. It is located immediately to the right of the steering column and should be on the "cable bus" in the same location, providing that area is original.

Probably the most common fault with the dash lights is with the rheostat... have you tried wiping the contacts constantly for a few minutes?

Relays in fuse box... one is for the fuel pump, I know that much. I'm pretty sure there are only two in my 6.9's fuse box and I haven't looked into what that is for. Then there are those in-line fuses... no idea what those are for either, at this stage either.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

13B

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I'm going to pull the intrument cluster out soon to check the globes in it, and the rheostat, so that should give me decent access to the wiper relay on the steering column... fingers crossed.

I.
450SEL 6.9 #5440 = V MB 690 , 450SE # 43094 = 02010 H , 190E/turbo # 31548 = AOH 68K

s class

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The wiper "relay" is bigger than the other aluminium cubes as TJ says, and is usually in black plastic.  The reason for the larger size is that it is much more than just a relay - there are electronics inside for the speed variation and intermittent functions. 

'76 6.9 Euro, '78 6.9 AMG, '80 280SE, '74 350SE, '82 500SEL euro full hydro, '83 500SEL euro full hydro , '81 500SL

WGB

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There are normally only two relays in the fuse box in Australian Cars.

The harness will have numbers on them if they are original and the numbers will correspond to the numbering on the wiring chart.

US cars have three - I think the third one is related to the airconditioning system as in their automatic system the compressor clutch is disengaged when using the starter motor.

It is possible that an extra one has been added to control another circuit eg burglar alarm, as it is an easy place to get at the wiring.

Bill

13B

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Finally got to tackle these problems today and found the following:

It was the rheostat stopping my dash lights from working, so I bypassed it and the console lights came on again.  I then had to pull the heater control panel apart to replace many of those tiny fiddly globes, now everything lights up.

I changed the rear window heater relay because the heated rear window would never switch itself off after 30 min, so I'm pleased it does now.

To get to the relays under the dash its best to remove the under-dash knee bolster and black air duct amd while at it remove the instrument cluster.  Most stuff is then easily accessible.

I changed the wiper relay but there was no difference, so I connected a spare combination switch to the 20(?) pin connector and again no change.  The only thing I can think left to change on the wipers is the wiper motor as from the wiring diagram there doesn't seem to be other relays related to wipers.  There must be some smarts or a relay/switching unit on the wiper motor which parks the wipers after they are switched off...  project for another time.

In the meantime can someone explain to me the operation of the combination switch on early cars.. The rocker switch is maked I, II, III and you push inwards to do something (?).  Also my car has the winscreen washer button above the footrest, and I believe if you hold it down for more than 3 seconds its supposed to bring in the wipers for a couple of swipes while water is sprayed on the windscreen... it doesn't, it just sprays water...

Thanks,

I.
450SEL 6.9 #5440 = V MB 690 , 450SE # 43094 = 02010 H , 190E/turbo # 31548 = AOH 68K

SELfor50

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Good to hear you got all them other fiddly bits working.  The wiper switch when pushed in is supposed to instantly wipe 3 times (mostly what I use unless it's raining dogs), and hold it longer it sprays the water.  Funnily enough, for me it's the other way round - the wiping works, the water spray doesn't.. also probably to do with having no wiper water reservoir, but I also think the water spray pump doesn't work either.

It doesn't seem to me that it'd be the wiper motor if it works on Intermittent and High speed, but not slow.  Sounds like the wiper arm switch etc..  Maybe the wiring on number 2 isn't working.  I'm not familiar with the location on early cars, is it not the arm on the right side - is it somewhere else?

Cam.

Finally got to tackle these problems today and found the following:

It was the rheostat stopping my dash lights from working, so I bypassed it and the console lights came on again.  I then had to pull the heater control panel apart to replace many of those tiny fiddly globes, now everything lights up.

I changed the rear window heater relay because the heated rear window would never switch itself off after 30 min, so I'm pleased it does now.

To get to the relays under the dash its best to remove the under-dash knee bolster and black air duct amd while at it remove the instrument cluster.  Most stuff is then easily accessible.

I changed the wiper relay but there was no difference, so I connected a spare combination switch to the 20(?) pin connector and again no change.  The only thing I can think left to change on the wipers is the wiper motor as from the wiring diagram there doesn't seem to be other relays related to wipers.  There must be some smarts or a relay/switching unit on the wiper motor which parks the wipers after they are switched off...  project for another time.

In the meantime can someone explain to me the operation of the combination switch on early cars.. The rocker switch is maked I, II, III and you push inwards to do something (?).  Also my car has the winscreen washer button above the footrest, and I believe if you hold it down for more than 3 seconds its supposed to bring in the wipers for a couple of swipes while water is sprayed on the windscreen... it doesn't, it just sprays water...

Thanks,

I.

"Man who come first, wins race." -Unknown

-= 1978 - 450 SEL [Euro] =-  Locked
-= 1976 - 450 SE 6.9 #2 =-  New Heart

13B

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Thanks Cam, I know what you're talking about but since you don't own an early car you're misunderstanding the function of the combination switch is quite different to the later style combo switch fitted to our 6.9s... easy mistake to make, no probs.  The early combo switch has a rocker switch marked I,III,III instead of the twist-action swtich on post-76 cars.  You sort of select I (intermittent), II (slow), or III (fast) and then some other way (i'm assuming press in the end) to start the wipers moving according to the program requested in the rocker switch.

Doesn't help that I don't have a glovebox manual which describes the function of the early combo switch, only the late one.

Oscar do you have a scan from an early glovebox manual I can have a look at?

I.
450SEL 6.9 #5440 = V MB 690 , 450SE # 43094 = 02010 H , 190E/turbo # 31548 = AOH 68K

oscar

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Hey, you just got in before me, i was out looking at my car to see how it works.  I'll look in my books too plus manual.  FWIW I've got three ice cube relays in the box.  The car never had a rear demister, leccy windows, sunroof or an auxillary fan until I put one in.  Literally Povo's V8 cousin.  But I'll try and find what they're for.

operation of combination switch When ignition on:

Footswitch - pressing the switch immediately brings the wipers on for 3 wipes.  If pressing for longer it still continues for 3 wipes after the switch is released.

Switch markings   II    I    III
- If you move the rocker switch to III the intermittent wiper comes on with a 5 second gap.  Returning to middle stops it.
- If you push the end of the stick in the wipers wipe continuously at the first speed I.  Moving the rockerswitch now to II will make it faster, back to I (or the middle) slower and to III intermittent.  Pushing the switch in again deactivates the lot.
1973 350SE, my first & fave

SELfor50

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Hey, you just got in before me, i was out looking at my car to see how it works.  I'll look in my books too plus manual.  FWIW I've got three ice cube relays in the box.  The car never had a rear demister, leccy windows, sunroof or an auxillary fan until I put one in.  Literally Povo's V8 cousin.  But I'll try and find what they're for.

operation of combination switch When ignition on:

Footswitch - pressing the switch immediately brings the wipers on for 3 wipes.  If pressing for longer it still continues for 3 wipes after the switch is released.

Switch markings   II    I    III
- If you move the rocker switch to III the intermittent wiper comes on with a 5 second gap.  Returning to middle stops it.
- If you push the end of the stick in the wipers wipe continuously at the first speed I.  Moving the rockerswitch now to II will make it faster, back to I (or the middle) slower and to III intermittent.  Pushing the switch in again deactivates the lot.

Shyte.... That's some rocket science action.  ;D
I can understand the confusion. 
"Man who come first, wins race." -Unknown

-= 1978 - 450 SEL [Euro] =-  Locked
-= 1976 - 450 SE 6.9 #2 =-  New Heart

oscar

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haha, maybe it's just the way I explain things. 

Couldn't find anything about the footswitch, just the combo switch.  No luck on the cube identification so far.



1973 350SE, my first & fave

brettj

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Hi Oscar,

Are you sure that when you depress the washer foot pedal the wipers come on for 3 wipes automatically? My car doesn't do that. When I depress the foot pedal all I get is a spray of windshield washer fluid. If this action doesn't happen how do you correct it? Is the solution a new wiper relay cube?

brettj

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Hi Oscar, You were right in the operation of the windshield washer foot pedal. When applied the wipers should turn on. I checked my cars foot pedal operation and the washers work but the wipers do not turn on. I have a new wiper relay cube.  I'll install it and hopefully this corrects this problem.