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Discussion Starter #1
Can anyone help me understand what is going on here? I am replacing the seats in my 1997 E420 but the old seat does NOT have the yellow connector for the SRS sensor for the air bag!? My SRS light is on and I thought that this upgrade was also going to take care of that, but the NEW seat has the yellow connector for the sensor while the OLD seat DOES NOT have it (as pictured in the DIY).

Also, I can't see anything coming up from the wiring harness that would connect to the yellow connector. It seems really unlikely that I'd be missing the connection both on the seat and coming up from the car, right? Maybe one would break off, but both?

Can anyone shed any light on this? Is it a different connector on early W210's, or do early 210's not have the sensor?

See photos attached of the old seat, new seat and from the DIY.

Thanks in advance for any help!
 

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Discussion Starter #4 (Edited)
The light has been on for many months -- actually so long that I can't remember it not being on. I do think that it was off at one point in this car though. Can't be sure.

Regarding the additional connectors on the new seat... it is a multicontour + heated seat so they are for the extra features. I believe the square connector with the rectangular contacts is for the seat heaters. The round connector is an air connection from the rear vacuum pump for the air bolsters in the seat.

I'm completely baffled by this. I'm about to tear up the carpet looking for a sign of the wiring harness for the yellow connector! I've looked pretty well already though so I'm really needing to know if I'm looking for some other type of connector or if I'm looking for something that is NOT supposed to be there.

Without evidence on the old seat of a dangling wire for the seat sensor, however, I'm somewhat inclined to believe I'm chasing a ghost. The russian EPC does list some SRS sensors for the 97 E420, however. Could it possibly be connected in a different way for this year? One thing to note is that I don't think that I have an "airbag" indicator light that I've read about in other posts, and I don't have a switch near the shifter to turn on/off the airbag.
 

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Discussion Starter #6
No, I'm not sure that the seat does have a sensor -- either by design or by omission by someone messing with it. I'm about to tear it open to look as well if I can't find out! Just hoping someone can tell me if it is supposed to have it or not. As I said, I looked in the russian EPC and they do have seat sensors listed, and my SRS light is on and the seat sensor seems to be the most common cause of that. So there is evidence leading me to believe it should be there, but I can't find evidence of the connections everyone talks about with replacing it.

So the most likely scenarios are (1) this year/model does not have it, (2) it is connected differently for this year/model, (3) the connectors and possibly sensor are simply missing/cut, (4) I'm overlooking one or both and need to look harder.

Just seems really improbable that I'm overlooking both the wiring connection from the floor AND the wire/connection on the old seat.
 

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Discussion Starter #8
Yep, I believe that I've double and triple checked to make sure the side-by-side seats are both the passenger (the driver side is still in the car with seatbelt functioning properly so it has to be). And yes, looking at the passenger side inside the car as well. I'm about to go out and start tearing things apart even further and will quadruple check it all.
 

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Discussion Starter #10 (Edited)
Thanks. Here's a bit of an update. I've pulled out the seat on the passenger side and have even pulled up the carpet but there is no sign of another connector that would go into the yellow one on the new seat and as described in the DIY.

On the old seat, there is a gray wire going from the RED connector back to the rear of the bottom seat pad. From there, it goes into a hole and feels as if it goes to a sandwiched layer that would seem to be where the sensor pad would be.

The new seat also has the red connector but it is hard to follow the wiring on it as there are quite a few more wires and tube than the old seat for the extra features. It didn't seem like the yellow connector wire ran through the same hole in the back of the seat though. Hard to tell for sure and I don't really want to disassemble the new seat until I have a better idea of what is going on.

I'll probably rip open that old seat to see for certain if there is a seat sensor in it and how it is wired. I'm leaning toward the belief that it is in there but it is a different version part and it is wired differently. If that theory is confirmed, I'm guessing that I'll have to get a "old" version sensor part to install in the seat unless the new seat happens to be backward compatible.

Also, I'm getting carsoft setup in a week or two so I'll try to check and clear the codes before going much further. If the new seat sensor is backward compatible, maybe I'll be all set.

In the meantime, if anyone has any further thoughts or access to WIS for more info, I'd greatly appreciate any advice!
 

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Discussion Starter #12 (Edited)
Here are photos of the car without seats and carpet! It's like the space shuttle down in here! But no sign of anything to plug SRS seat pad into a wiring connection compatible with the little yellow connector shown in the DIY. The wiring is hidden inside a raceway and it looks pretty clean and simple with them closed. The photo of the wiring is with the raceway open near the passenger seat area.

In addition to new seats, I'm doing a COMPLETE color change. So black carpet is going in from an E55 in place of the tan carpet. Very much looking forward to having dark carpet that won't show as much grime.
 

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well, maybe I can shed some light on your situation. I have a 97 E420. the passengers seat does NOT repeat NOT have a yellow connector, only a red one. Yes it does have a SRS sensor pad.

Now in 98 or maybe even late 97 (remember 97 E420's were built starting in Feb 96!) they added the ability to turn OFF the passenger air bag when used with a carseat etc. that may be what the yellow connector is for, and it may be that the seats you got, or at least w/o changing the wiring and SRS pad, are not compatible with your 97.

Ok, now to the SRS light. IIRC when I had my seats out, and the radio on, the SRS light came on. To reset the SRS light, i think (not positive) that I needed to use carsoft to clear the codes when I connected the seat back up. either that or it finally went off afte so many cycles. Now, if your seat has a bad SRS pad in the seat, that could be the root of your problem.
 

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Discussion Starter #14
WOW - thank you so much for confirming that, E-420!! I thought I was losing my mind. Looks like I'm probably going to end up having to rip apart the seat to install the right SRS sensor pad. That is, unless somehow this new seat is backward compatible. I ordered a carsoft multiplexer about a week ago so will find out when that arrives.

I'm feeling pretty good about these seats being compatible now that I've swapped the control modules on the bottom. They are adjusting just fine now, and I think that functionality is pretty self contained in that box. It would be nice to know if swapping modules was the appropriate fix for this or if there was another solution. Maybe time will tell and there will be a "gotcha" with something not working right as a result as I finish this up.

I should be able to just install the right SRS sensor pad if that is indeed the issue with the old seat. I ran the tubing for the multicontour function today and can hopefully enable my vacuum pump for that when carsoft arrives as well. Then, the last thing is getting the retrofit seat heater wiring harness from the dealer and running that between console switches, each seat and the fuse box back by the battery.
 

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"The overall best use of the E420 is not for commuting to work, impressing our mothers, or making sibs jealous. It's for driving as though you were being chased by dogs. Across Montana."

bought my E420 from my brother, picked it up in spokane, and 3 hrs. later got stopped for speeding in Montana on the way to visit my folks. Luckily the 420 has good brakes and I was able to scrub off lots of speed before he got a fix on my speed and I got away with a warning. Liked the old Montana "reasonable and prudent" "speed limit" much better. Hard part was explaining to the officer that yes I own the car, no I don't have a bill of sale, yes I have insurance, you could call the PO to verify the sale, but he is living in Dubai now even though his registration shows a spokane address.........
 

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Discussion Starter #16
Yeah, I love my E420 and the M119 engine. It's been such a great car. Lately I've thought about getting an E55 but I do hate the thought of giving up the M119 and not knowing much about what I'd be getting into. I was going to put off this seat upgrade and others and instead just clean up the car to sell it but decided to just go for it and maybe keep the car just a little bit longer. I'm already thrilled with the E55 interior and it is only half way in. Feels like a different car!
 
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