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1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
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Discussion Starter #1
Yesterday I took my car out from its Winter & COVID storage for the first time, since November.

Runs great & all save one problem I noticed straight away..

The dashboard directional indicators flash & click rapidly.. The Hazard Warning indicator seemed to flash at normal speed.

Neither left nor right front directional lamps indicate at all.. and both tail lights indicate perfectly.

The bulb out light glows after I use the directional and will return to a dormant state each time the ignition is turned off.

All the other exterior lamps work as advertised.

In my experience, a directional indicator cycling/clicking fast means a bulb is out.. but BOTH at once? It seems unlikely...

I'll check the bulbs tomorrow before the heat of the day & see.

It sure would be easier than physically checking plug/jack X24.. somewhere inside the fusebox & below the fuse/relay rack..

Keep you posted.

M

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1986/1990 W126
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Is it worth unplugging and cleaning the terminals of the hazard switch, MBL?
I'm sure you've checked the fuses, but when I picked up my SEC from the previous owner it had been sat under a cheap cover on a damp mossy driveway. The indicators did weird things and made a really odd buzzing noise, until I wiggled the fuses. Fine since.

Hope it's a nice easy fix.
 

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1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
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Discussion Starter #3
Is it worth unplugging and cleaning the terminals of the hazard switch, MBL?
I'm sure you've checked the fuses, but when I picked up my SEC from the previous owner it had been sat under a cheap cover on a damp mossy driveway. The indicators did weird things and made a really odd buzzing noise, until I wiggled the fuses. Fine since.

Hope it's a nice easy fix.
Hey Ian,

Fuses, all nice new brass ones, were twisted to ensure good contact at the outset, followed by testing of all the lighting features & functions. All good on that score... city lights, head, tail, plate lamps, rear turn & rear hazards are all OK.

So tonight, wrestling with the car cover in a stiff breeze, I removed, inspected & ultimately replaced the RT frt turn indicator bulb,, as the lead ‘button’ had worn completely flat! Must have been the original 1991 bulb I’d say.

Tested again without success.

As far as the connections re hazard switch.. it is working as expected, both from our (collective) car expectations & the fact the circuit diagram supports that theory.

The included diagram above shows the various directions of current flow given differing conditions and as this presents the very same symptom in BOTH modes [Hazard or Combination Switch operation L&R] & now front bulb replacement without positive result.. I must consider the possibility of the X24 connector.. The only place downstream of the feed to the L&R rear indicator bulbs.. those circuits share connectors in a common plug/jack.

The rears work always whether Directionals or Hazards.. that is Key: OFF / Key: ON. Whereas the fronts, in either case, do not function at all.

There is a bunch of other things I wanted to accomplish this driving season, mechanical things,,

Now with this & mouse/mice in the car, my focus is amended.

I’m hoping to get positive results soon too..

Thanks

M.
 

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1989 300SE 232k miles
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1,449 Posts
My experiences are these: in non-MB cars, faster turn signal indicator lights in the dash mean a bulb, any bulb, anywhere in the exterior lighting system, is out. And I had to test everything to find it. ...even those stupid license plate lights.

In my r129’s, I don’t remember a faster flashing dash bulb when activating the turn signal, but the bulb out warning light did help me localize it. If the warning light came on when I turned on the fog lights, it was a fog light bulb. If it turned on when the vehicle went into reverse, it was a reverse bulb. That sort of thing.

When I bought my w126, the bulb out warning light came on within the first day. It did not help me localize, like the r129. I found a blown left rear bulb, and replaced it. Next time I started the car, bulb warning light. It was a blown right rear bulb, but for a different set of lights. Replaced that. Two days later, the bulb warning light. This took time to find, as it was in the 3rd rear break light.

My point being, sometimes bulbs just go. Don’t rule that out.
 

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Outstanding Contributor
1989 560SEC, 1989 560SEL, 1995 E420
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Three ideas:

1. I couldn't agree more with Ian and the hazard switch. On the way home from buying our SEL, the blinkers stopped. I remembered advice to 'exercise' the hazard switch and turned it on and off a bunch of times. Problem solved. I know your problem is just in the fronts but I would still do this first.

2. Consider your grounds. I think there's one at each headlight at the body. Tiny nut and bolt down low behind the headlight near the radiator.

3. Consider the bulb out module. Swap with your other car.

Good luck!
 

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1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
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Discussion Starter #6
Three ideas:

1. I couldn't agree more with Ian and the hazard switch. On the way home from buying our SEL, the blinkers stopped. I remembered advice to 'exercise' the hazard switch and turned it on and off a bunch of times. Problem solved. I know your problem is just in the fronts but I would still do this first.

2. Consider your grounds. I think there's one at each headlight at the body. Tiny nut and bolt down low behind the headlight near the radiator.

3. Consider the bulb out module. Swap with your other car.

Good luck!

OK LM & Ian too.

Many thanks for your counsel.

After reading above and pouring over the directionals/hazard warning switch wiring diagram [again above], my understanding of the two related circuits function, I can definitely see how a poor internal contact within the hazard switch can render both systems inoperative/ or cut off one side or the other as all the power, switched or hot at all times routes through it.

Off, switched power is routed through it to the flasher, then to the turn signal portion of the combination switch. In turn, the directional switch provides the ground circuit through the left OR right directional bulbs. Blinka-Blinka!

ONHot at all times’ power is routed to the flasher unit and the flasher OUTPUT is now is now routing through the hazard switch, bypassing the directional switch and fed [at connector X63] directly to the left and right [F&R] turn signal indicator bulbs for ground.

Looking at the left & right power feeds from the directional switch, front & rear indicators become wired in parallel at connector X18, then the wiring for both the FRONT indicators routes through another multi-pin connector X24 before separating to the respective front indicators.

Today, I replaced both front directional bulbs with matching new, and tested the bulb feed plugs X1 for ground supply & pulsing 12Volts. Ground I got. 12V. Nada,

Both front indicators are inop.. Everything else plays as advertised, 4-ways key off/on.. Directionals work rear only and a bit faster pace.. [‘bulb out’] pace.

I will swap the bulb failure module with the other car as suggested ..

I still am convinced there is something amiss at the X24 connector, somewhere in the bowels of the fuse box, under the relay support frame....

Have a good weekend all.

M
 

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1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
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Discussion Starter #7
But WAIT There's MORE X24!

This afternoon I had reason to use the horn and low & behold the Two Tone version did not work, Fanfare ones [I think the round flat ones by the Aux fan] do.

'She who must be obeyed' assisted and both fanfare ones got current and were LOUD!

The horns, both versions, connect via the above mentioned X24 connector.

"Curiouser & curiouser..." remarked Alice **

I am thinking more & more, this is no coincidence..

Its gonna have to wait as its 91F here ATM.

M

** From Alice's Adventures in Wonderland by Lewis Caroll
 

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1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
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Discussion Starter #8
Three ideas:
3. Consider the bulb out module. Swap with your other car.
Good luck!
Thank you luckymike..

I took the car over to visit with my US '87 to swap the bulb-out relay..

Referring to my red '91 here: All the other relays came out with minimal drama, but the long one was a real B E A R to remove... It finally popped up with two of the connector jacks still connected! I had to gently persuade them to release the module pins.

As the two connectors were pulled away from their mounting, with a LOT of wires exposed, I thought I'd see if I could locate that X24 I've been going on about these last days.....

I did not find it, but did find this job has just turned into an insurance job after a deep look into the fusebox wiring!

Apparently, mice had been munching wires & storing tiny seeds inside the fusebox!
That fusebox is pretty much sealed to the firewall with a rubber conduit bellows, all the engine compartment wiring enters with multi-wire grommets... They must have come through the firewall bellows from behind the dash... perish the thought!

I put it back together, did not swap components, when I got home I installed a battery cut-off switch on the NEG battery terminal. Left it OPEN as I am nervous now of potential electrical fire.

I then looked more carefully at the interior for mouse evidence.. there was a small amount under the rear seat cushions & backrests.. Those are now up here in my office.

So kudos to you LuckyMike for inspiring me to take a deep look into the fusebox!

M

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1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
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Discussion Starter #10
Thanks, Ian,

I will get through this... and without a fire too!
 

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Outstanding Contributor
1989 560SEC, 1989 560SEL, 1995 E420
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Thank you luckymike..

I took the car over to visit with my US '87 to swap the bulb-out relay..

Referring to my red '91 here: All the other relays came out with minimal drama, but the long one was a real B E A R to remove... It finally popped up with two of the connector jacks still connected! I had to gently persuade them to release the module pins.

As the two connectors were pulled away from their mounting, with a LOT of wires exposed, I thought I'd see if I could locate that X24 I've been going on about these last days.....

I did not find it, but did find this job has just turned into an insurance job after a deep look into the fusebox wiring!

Apparently, mice had been munching wires & storing tiny seeds inside the fusebox!
That fusebox is pretty much sealed to the firewall with a rubber conduit bellows, all the engine compartment wiring enters with multi-wire grommets... They must have come through the firewall bellows from behind the dash... perish the thought!

I put it back together, did not swap components, when I got home I installed a battery cut-off switch on the NEG battery terminal. Left it OPEN as I am nervous now of potential electrical fire.

I then looked more carefully at the interior for mouse evidence.. there was a small amount under the rear seat cushions & backrests.. Those are now up here in my office.

So kudos to you LuckyMike for inspiring me to take a deep look into the fusebox!

M

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You're welcome.

VERY sorry to hear about the mice. I just dealt with them in our E420. One feels so violated.
 

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1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
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Discussion Starter #12
Needing to know the extent of the damage will help me determine the best avenue for repair.

With that in mind, I opened the fuse box & raised up the relay bracketry to expose the wiring and that old chestnut the "X24" connector.

I found a LOT more than I wanted to see actually. Yes, its what I needed to know. But Oh mama pajama!

I'm guestimating over a dozen circuits to be compromised in one way or another, some severely damaged.

To be clear: So far there have been NO short circuits/burned wires..
Such a condition would be so very, very MUCH worse.

Currently, the battery is disconnected and will not be connected again until after a repair is underway/completed.
Much as I do not care for this situation, I consider myself VERY fortunate indeed to have avoided a fire, given these circumstances.

Tomorrow, if it's nice here, I'll pull the instruments and do some negative inquiry as to wiring conditions under the dash.
Additionally, I'll pull the floor mats up and take a look at the control units too.

Later,

M.
 

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Oh what a horrific thing to discover. Gutting. But actually not so bad to fix in the grand scheme of things I hope.
 

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1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
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Discussion Starter #14
UPDATE:

To date, the rear seat cushions & backrests are removed and mouse evidence was found in the right trunk well, under the right rear seat cushion, at the base of the RT upholstery panel covering the RT side seat belt presenter and minor nibbleage to the RT rear seat foam cushions.

So far, there seems NO damage to the rear or front stock OR aftermarket carpet mats on the car.
ALL evidence seems below the surface and out of sight.

Today, I returned with some tools.

After removing the passenger side floor mat & carpeting panel, I found more mouse evidence. Lots of eaten birdseed and chewing evidence to the console carpeted right side panel. I believe they came through the tunk, over the right rear wheel arch, forwards behind the passenger seat belt pre4snter panel, then underneath the carpeted right side door sill/rocker panel covering forwards. They then accessed further, traveling the gaps between the MB floormat padding to the firewall & center console area.

It is not at ALL pretty.

I removed the false floor above all those control units and found no access evidence!

I took lots of pics and left my phone in the now covered car. Ufff!

Mahayana

M

Hand sanitizer is wrecking my nails!


Best to you ALL!
 

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1986/1990 W126
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Oh no 😯 How do you think they accessed in the first place? The vent flaps maybe?
 

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1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
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Discussion Starter #17
Oh no 😯 How do you think they accessed in the first place? The vent flaps maybe?
Hey Ian,

Definitely the rear air extraction flaps. The first clue was the mouse nest in the right trunk well. Luckily, it was in a waterproof/plastic lined tote bag... I then traced it, by rear seat cushion & backrest removals, to the right side panel that under the rear side glass.

Removal of the right front carpets show more mouse evidences including behind the false floor and into the center console area.

Today I removed the leftover side bolster & carpeting and saw lots of evidence from the console area..

Further research showed little to no wiring damage in those areas.

Back at it tomorrow,

Thanks,

M.
 
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