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DerFuror
02-07-2011, 09:08 PM
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Postby gerryvz on Tue May 26, 2009 12:15 am

I've seen more than a few W124s and a couple or three E500Es consumed by fire. Seems to be a wiring issue in the dash area behind the hood release lever area. I'm not sure if it's wiring behind the dash or wiring that comes in from the door/kick panel/dead pedal area that shorts out somehow and starts a fire.

But I've definitely seen 3-4 cars (including a 1995 E320 wagon that I formerly owned ... which caught fire several years after I sold it) with this issue. Enough to think it's an issue, but not a widespread one.

Cheers,
Gerry

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Postby wpirie on Tue May 26, 2009 8:43 am

"Seems to be a wiring issue in the dash area behind the hood release lever area. " Okay, I took this information and a web search turned up this at honestjohn.co.uk in the car-by-car review area pertaining to the W124 chassis..."Dashboard fires can be caused as follows: fault is due to a un-fused connection to the boot courtesy light. The power cable runs in a curved tube alongside the boot hinge on the drivers side and after a period of time (opening and closing the boot lid) this cable shorts to earth, which results in the power lead heating up and the resulting fire is started at its un-fused connection to the fuse board in front of the driver and to the right of steering wheel." Checking the wiring diagram I find the trunk light is connected to "X30 accessory Equipment connector block" which is fused at fuse C. Note honestjohn is discussing rhd cars so maybe this connector is in the hood release lever area in US spec cars? Maybe worthwhile inspecting the trunk light wiring in the hinge area.

wpirie

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Postby gerryvz on Tue May 26, 2009 3:08 pm

I believe this topic was discussed in a thread on Scott's 500x board perhaps about a year or year and a half ago. I think it's a very real issue/flaw with these cars but not one that many people know about. The HonestJohn.co.uk link that you mention is one of the only real mentions of the issue I've also seen on the web.

I think it makes sense to proactively try to fix/fuse this connection. I haven't done it yet but it's on my list of "to dos".

Cheers,
Gerry

gerryvz, have you completed this "to do" or investigated the wiring any further? Any findings?


An issue worth consideration / investigation. This is the time of year when many of our cars are tucked away in storage on a charger. An unattended trickling potential time-bomb is never good.

I've found a few possible consumer complaints, but nothing else directly related to this non-fused trunk lamp issue. The vast majority of consumer complaints are of course engine harness related. An Allworldauto.com research on 1993 500E shows 1 recall & 2 TSBs regarding other root-cause issues. The recall is fire-related but pertains to headlamp wiper pump system.

There are also 2 more ConsumerGuide Automotive fire-related issues pertaining to W124 E Class '92 ASR & '92-95 passenger foot ramp listed further below.

Recall:
NHTSA Campaign Number: 96V175000
Defect Summary: IF ONE OF THE HEADLAMP WIPER ARMS BECOMES MISALIGNED, THE WIPER BALDE CAN LODGE IN THE GROOVE UNDER THE HEADLAMP. IF THE WASHERS ARE ACTIVATED WITH THE WIPER BLADE IN THE MISALIGNED AND LODGED POSITION, THE WASHER PUMP WILL RUN CONTINUOUSLY EXPELLING ALL AVAILABLE FLUID.
Consequence Summary: PUMP OPERATION IN THE ABSENCE OF FLUID CAN CAUSE THE PUMP TO OVERHEAT AND CAUSE A VEHICLE FIRE.
Corrective Summary: DEALERS WILL REPLACE THE HEADLAMP WASHER PUMP ON THESE VEHICLES.

TSB:
NHTSA Item Number: 39181
Service Bulletin #: MBNA82/81
Replacement #:
Vehicle/Equipment Make: MERCEDES BENZ
Vehicle/Eqipment Model: 500
Model Year: 1993
Mfg Component Code: 121000 EXTERIOR LIGHTING:HEADLIGHTS
Date of Bulletin: 1995-02-01
Date Added: 1995-03-30
Summary: BONDING HEADLAMP LENS TO HOUSING. *TW

NHTSA Item Number: 39407
Service Bulletin #: 00340
Replacement #:
Vehicle/Equipment Make: MERCEDES BENZ
Vehicle/Eqipment Model: 500
Model Year: 1993
Mfg Component Code: 011000 STEERING:WHEEL AND HANDLE BAR
Date of Bulletin: 1993-06-01
Date Added: 1995-11-01
Summary: MODIFIED STEERING LOCK. *TW

Other Fire/Electrical hazards:
1992 w/"ASR" automatic slip control: Plastic brake-hydraulic hose was misrouted too close to preresistor for auxiliary cooling fan, which becomes hot under certain conditions; could cause hose to melt and leak brake fluid onto hot preresistor, resulting in possible fire.

1992-95 E Class 124: Front passenger metal footrest can, over time, abrade through wiring harness, causing short circuit; wires might then overheat, engine may stall, or airbag could inadvertently deploy.

gerryvz
02-08-2011, 11:13 AM
I haven't thought about this for the past few years, nor have I heard any more fire stories. What prompted this thread originally was that I had both heard and seen stories of dash fires originating in the left driver's side dash area somewhere near the hood release / headlight switch area that had caused catastrophic vehicle fires. I am aware of the TSBs relating to the headlight wipers and front passenger footrest. I have actually investigated my footrest areas on the W124s that I own but didn't see any evidence of problem so replaced everything back and went on my merry way.

Of course as a vehicle ages (any vehicle) there are probably elevated chances of something leaking or abrading or shorting and causing a fire. You probably never know about and/or can't control this happening in the majority of situations. I don't think I've ever heard of an E500E catching fire directly due to a wiring/electrical issue (or any other type of issue).

Unrelated, mostly, is a short in the wiring that my 1995 E320 Wagon has in the wiring bundle where it flexes at the rear tailgate. It disconnects and reconnects intermittently, causing the rear window wiper and washer to work something and not work other times. It's a common issue I hear (no fires or anything, just intermittent operation of these) and I need to get in there and wrap the connections with electrical tape or heat-shrink tubing to replace the worn insulation. I think another issue relating to the "biodegradeable" wiring insulation -- it doesn't survive constant flexing of the wiring bundles/harnesses (and as we well know, engine heat).

Cheers,
Gerry

tomer
10-07-2012, 04:50 AM
I hate to bring this topic back up but I had an electrical fire from the headlight washer pump last weekend. I had to jump on a plane the next day and won't be back in California till end of this week, so pics and details to follow.

I have had the 94 E500 for about 3 months now, and neither windshield nor headlamp washers worked I discovered a couple weeks after getting the car. I was annoyed it was not caught in the pre purchase inspection, but figured I could have fun troubleshooting it...

Before heading to a golf tournament I tried to activate the washer pump and check for pump noise. I could hear nothing, and somehow pushed the squirt on the stalk with the headlights ON, and did not notice that the pass side headlight wiper arm parked in the vertical position... I am GUESSING this energized the headlight washer pump IF the headlights are on??

I ran couple errands before taking off and did smell the distinct smell of electical burning... checked around and could not determine the source... Took off for the tourney with the headlights ON, and within a mile SMOKE ROLLED OUT FROM UNDER hood... panic stop and headlights OFF and you would not believe how melted the washer pump AND wiring is... Parking lot McGiver operation followed, Got it pulled apart, wires cut back and taped off, water on pump to cool it down... sheeeeeeeeeeeeeeeesh...

DOes anyone know if the pump is supposed to have any thermal protection built in?? I am guessing I am a victim of a bad pump that perhaps has not worked for years?? And when it was stuck energized decided to let the smoke out ???

Somehow in all the confusion (I did NOT push the squirt button again I am sure that morning) the headlight wiper is now parked correctly???

Once home this weekend I am curious to see if the headlamp wipers will cycle/wipe and park correctly, and if the wiring for the headlight washer pumps still gets activated by the wiper motor?? Need to find my test light and hook it up!

Not fun...

Be ware.

Tomer

tomer
10-08-2012, 09:23 AM
bump.

Any inputs on the failure mode of my headlight washer pump and the pass side headlight wiper parking vertical is much appreciated.

I am baffled how the pass side headlight wiper somehow returned to horizontal (proper) position after the fire...

DerFuror
10-08-2012, 10:45 AM
Any inputs on the failure mode of my headlight washer pump and the pass side headlight wiper parking vertical is much appreciated.

I am baffled how the pass side headlight wiper somehow returned to horizontal (proper) position after the fire...

This thread (http://www.500eboard.com/forums/showthread.php?3262-HOW-TO-Headlight-Wiper-Washer-System-Diagnostics-and-Repair) provides a comprehensive overview on the headlight wiper system's fundamentals of operation & problem diagnosis.

The right-side headlight wiper motor contains an extra set of points which energize the headlight wiper pump. The points may have become stuck in the energized position, eventually overheating the pump (was there any washer fluid in the reservoir?). The washer fluid provides pump cooling. Similar to what is stated in the Recall info above, expelling the fluid while under continuous operation can lead to a meltdown & fire.

I suspect your situation may be a variation of this consequence paradigm.

NOTE TO ADMIN: please move this entire thread over to Electical Forum; a more logical location than Interior Topics.

samiam44
10-08-2012, 11:01 AM
I don't remember much of scott's 500e website.

Do ppl just inspect the light- boot is the trunk light correct? Most MB wiring has some anti-chaffing sleeve. Probably time between the outer sleeving failure and wire insulation cut through. I could easily add an inline fuse upstream of the light.


Michael

Jelmer
10-08-2012, 03:35 PM
NOTE TO ADMIN: please move this entire thread over to Electical Forum; a more logical location than Interior Topics.

http://t0.gstatic.com/images?q=tbn:ANd9GcTDQlU-Qwq7l4xVloENnT2lgmAhORElh8NdLXhjg9EKP3aZLm_yzTr-GIWN

tomer
10-09-2012, 02:30 AM
Thanks for moving this thread!!!

Derfuror, yes my washer fluid resevoir was and is full, so the pump did not empty the fluid. In fact the headlight washer pump did not pump anything...DId not make any pumping noise... Hence my guess is the pump was somehow siezed up possibly for years with the previous owner, and somehow the headlight wiper motor got stuck vertical and applied voltage to the pump...

I will do some checking this weekend. IF my headlight motor survived this melt down, that is one heck of a design... Note the blind optimism here :-)

thx
Tomer

DerFuror
01-29-2013, 09:32 PM
https://www.500eboard.com/forums/images/imported/2013/01/1.pngOriginally Posted by 500Espot
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Postby gerryvz on Tue May 26, 2009 12:15 am

I've seen more than a few W124s and a couple or three E500Es consumed by fire. Seems to be a wiring issue in the dash area behind the hood release lever area. I'm not sure if it's wiring behind the dash or wiring that comes in from the door/kick panel/dead pedal area that shorts out somehow and starts a fire.


:detective:...Continuing to play connect-the-dots detective regarding this topic's original post. A related thread (http://www.500eboard.com/forums/showthread.php?3797-Opinions-Wanted-No-Start-condition-after-work-yesterday&p=37945&viewfull=1#post37945) provides additional insight to a possible source of this Potential Electrical Fire Issue.

Tomer, you seem to be our involuntary participant for a lot of the recent electrical fire research. I hope your fire insurance is up to date & you have and are using a battery cutoff switch until your electrical issues are resolved. Be safe & check the condition of that lower harness!
:fun:

gerryvz
01-29-2013, 10:07 PM
Unrelated, mostly, is a short in the wiring that my 1995 E320 Wagon has in the wiring bundle where it flexes at the rear tailgate. It disconnects and reconnects intermittently, causing the rear window wiper and washer to work something and not work other times. It's a common issue I hear (no fires or anything, just intermittent operation of these) and I need to get in there and wrap the connections with electrical tape or heat-shrink tubing to replace the worn insulation. I think another issue relating to the "biodegradeable" wiring insulation -- it doesn't survive constant flexing of the wiring bundles/harnesses (and as we well know, engine heat).Soon after this post, the rear tailgate wiper/washer and window defroster stopped working altogether. Interestingly, I just recently ordered and replaced this wiring harness between the body and the tailgate on the wagon. Indeed the brown ground wire was snapped in half, purely from flexing.

Once I replaced this harness, the rear wiper and washer system started working perfectly again. Not my favorite job to fix - it was a pain to feed the new harness down into the tailgate and I had to do a sort of "fishtape" exercise to get it fed through.

Cheers,
Gerry