W124 Coupe; Seat belt Presenters Trouble Shooting

IslanderRE

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Apr 8, 2006
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21
Evening All,
Trying to get to the bottom of the seat belt presenters not working. Have carried out the following checks:

Passenger side seat belt buckle; disconnected the wire under the seat and checked using a multimeter.
Belt in: 4.3 Ohms Belt Disconnected: 4.3 Ohms
Drivers side seat belt buckle; disconnected the wire under the seat and checked using a multimeter.
Belt in: 4.6 Ohms Belt Disconnected: 0 Ohms

Would I be right in thinking the Passenger side seat belt buckle internal switch is not operating correctly????

Removed all four switches from both door jams; all giving a reading of approx 2.4 Ohms when closed and 0 when open. Therefore I think all four are operating correctly.

With the side cards off, I found all the wires disconnected from the presenter motors so I connected them as per the pictures......... I do not know if this is correct but the wires seemed to fall that way so to speak.
driverssidemotor.jpg
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These photos below show the wires connected to each door switch, again don't know if these are correct.
passengersidei.jpg
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driverssidej.jpg
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Also, a blank fitted between both drivers side switches appears to be missing some connections...... I'm thinking, perhaps wrongly, that this is connected with the original Infra Red alarm / central locking system which is now not operational as an aftermarket alarm is fitted.
p1020878.jpg
[/IMG]

I changed out the white fuse too with a new one just in case but no joy. So folks, could anyone tell me if the motor wiring is correct, does the switches wiring look okay too and is my thoughts about the passenger side belt buckle been faulty correct??

Thanks all...... I'd appreciate anyone's ideas or thoughts on the above.
 

WDB124066

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Apr 17, 2009
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1996 E320 Sportline Cabriolet x 2
Your motor wire & micro switch terminal points match the unit I have here if this helps a little...
 
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IslanderRE

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Excellent Stuff WDB124066,
Thanks for that...... I guess I got lucky connecting up the wires!!!!!!! I'll put back the side cards probably tomorrow or the weekend now I know the wire connections to the motors are correct.
Car is a bit of an electrical nightmare as many, many hands have been playing with the electrics inside. Another thread will be posted in the upcoming days about the radio wiring as it too is a connection nightmare..... the joys!!!!!
 

WDB124066

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1996 E320 Sportline Cabriolet x 2
You're welcome.

If you can describe how to pull those door switches without damaging them, I'd be willing to go have a look in a Cab for you...
 
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IslanderRE

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Apr 8, 2006
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WDB124066,
I the photo below, I have pointed to the two protrusions on the sides of each switch. Using a pliers, I simply squeezed both protrusions together and pulled the switch out.
driverssideblank10th.jpg
[/IMG]

Many thanks for the help.
Islanderre
 
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IslanderRE

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Still no further along on this lads despite WDB124066's help.
If anyone can give a heads up on anything I'd majorly appreciate it.
Regards,
Paul
 

WDB124066

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1996 E320 Sportline Cabriolet x 2
Mine is quite a bit different to yours, I have purple wires to add to the mix, I only have one connector block per door and I don't have spade connectors......
 
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IslanderRE

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Balge & WDB124066,
Cheers for the replies...... the wiring diagram I'll print out and see from there.
I reckon the spade connectors are associated with the retrofit of the alarm and disconnection of the factory fitted central locking.
I spend another few days at it and box it up for the summer after that.
Thanks all...
 

escosys

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Jun 5, 2016
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230ce
More seat belt problems

Hi
Recently bought 1988 300CE and passenger's side extender didn't work, so replaced it with one from a dealer. Now works fine except that on switch on and sitting in driver's seat and no passenger, both extenders move out. Insert the driver side seat belt and the extender retracts immediately. The passenger side retracts after 30 seconds or so, with or without a passenger. I suspect there are 2 switches, one to detect a bum on the seat, which extends the extender, and another which detects the seat belt buckle latching (or else the seat belt switch is in series with the seat switch and breaks when the belt is inserted). If the seat switch is shorted, then this gives the symptons above.

But is this all correct? Any thoughts appreciated.
 
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coupe addict

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Jun 7, 2010
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Location
penzance cornwall
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e320 coupe 1994
It is possible to stop the arms from presenting by pushing them back in just a little too far, and owners sometimes do this if the operation is tiresomely erratic. Giving the presenter a helpful pull when it is failing to present may then be enough - but there are sadly many more possibilities.
I personally have never encountered a 'bum-on-seat-sensor' - I think its only about whether the door has been opened for presentation, and then either buckle insertion or, in its absence, passage of time, to trigger retraction.
 

escosys

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Jun 5, 2016
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230ce
Thanks for that. Any idea of how to get to the switch in the buckle?
 

ConorMurphy

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Nov 21, 2020
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Location
Rainhill, UK
Car
300CE
Hi, just I'd share some recent experience I had with the passenger presenter in my 1990 CE. Purchased the car 4 months ago with the drivers presenter working perfectly but passenger side not working at all. Therefore no fuse problems etc. The door switches all worked fine. I removed the seat back rest and trim panel covering the presenter. The mechanism all looked good and could be moved manually with a bit of effort. Also the switches on the presenter were correctly adjusted and checked ok for continuity. Finally I pulled the control module (mounted on the presenter). I could measure voltage coming off and on to the input side of the module so started to figure there was a problem with the module as there was input but no output. I could open the box with a little persuasion, but I'm no electronics expert, so took it to a local guy. He only took a quick look visualy and said 90% of problems on boards like that are the capacitors failing. He swapped out the capacitor and in doing so he could see that it had leaked and slightly corroded the board. He put in a new capacitor and soldered a tiny wire link to bridge the corrosion.
He didn't have time to test the board, but said it was probably the issue. Anyway I took it home and plugged it in and hey-presto the presenter works (possibly for the first time in decades).
I'm only writing all of this as nearly all the threads on this issue focus on fuses, switches and gears etc. My electronics guy said capacitors like those are very prone to failure after 10 or more years.
Thanks Conor
 

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