W124 Passenger Airbag Retrofit Project Completed (with pics) - PeachParts Mercedes-Benz Forum

pwogaman · #1 07-04-2009, 10:34 PM

I just finished my 300TE passenger airbag retrofit project! It was as simple as playing with Lego’s, only I had to move a whole lot of them around and it took a little more time than I expected it would. Still, it was just as fun.

I did the project “by the book.” That is, without splicing wires or modifying parts. Every replacement piece installed to do the job came from various donors with the passenger airbag as original equipment. The retrofit was actually an option that a dealer could add, so I figured, why not me?

I also took loads of pictures and will put them into a pictorial sooner or later with detailed instructions so anyone with enough of a desire can do so as well. In the mean time here are some samples:

To start with, no airbag as I recently bought the car:

Here is the donor harness and control module. Removing it for the donor car was a pain. There are connectors at the front seatbelts, front seats, each airbag, the underhood test port, the control module, the test plug, and at the instrument cluster SRS warning light. I did not want any splices, so getting it out meant no cuts. Just the same, I went over every last mm of wire checking for kinks, scraps, corrosion, etc. . .

To properly lay the harness you need to access the under carpet cable trays, which means removing the front seats. This picture was taken from the driver’s seat area looking towards the center console.

I went ahead and removed the carpet all the way so I coulds scrub the hell out of it.

I used up a lot of elbow grease but the result was well worth it.

I found about $3.00 in change.

Here is getting the driver’s seatbelt connector through the cable runs. Note the green tape on the cable; I put red tape on all the old connectors and green on the new before I started the switch-over. I did not want to waste anytime running the same connector twice.

Here is the old (right) and replacement (left) control modules. Note the number of pins is different.

Here is where the control module is buried away. Note again the red and green tape.

One of the more difficult things to do was to replace the underdash support bracket that runs from the passenger door at the “A” pillar over to the ignition switch.

Getting to the four nuts by the ignition switch required lifting the front of the dash about an inch.

Here are the two bars side by side. The donor is on the top.

Here is the new airbag support hardware with rests on the under dash support bracket.

Here is the finished product!

How I can’t wait to test it - okay, not really. The test SRS warning light works okay though.

pawoSD · #2 07-05-2009, 12:55 AM

All I can say is....why? I would prefer my cars have no airbags at all. My 300SD has none, which is awesome, and the 300E has just the driver.....why give up the glove box for an air bag?

Nice work/write up though, that is very helpful to see the W124 stuff disassembled.

ps2cho · #3 07-05-2009, 03:02 AM

Just curious...how long did it take you to remove all the seats + carpet in the car? I'm considering this for my 260E as the carpets probably need a good treatment outside the car. I used a portable carpet cleaner, but its too difficult to get into the hard to reach spots.

Skid Row Joe · #4 07-05-2009, 03:32 AM

Quote:

Originally Posted by pawoSD

I would prefer my cars have no airbags at all.

So, explain why?

pwogaman · #5 07-05-2009, 09:28 AM

Quote:

Originally Posted by pawoSD

All I can say is....why? I would prefer my cars have no airbags at all. My 300SD has none, which is awesome, and the 300E has just the driver.....why give up the glove box for an air bag?

Nice work/write up though, that is very helpful to see the W124 stuff disassembled.

I could say I did it for the insurance price break - of which there will be a slight one, but that would just be an excuse. I did it because I could and I really enjoy working on these cars. I love the way you can take a car with nearly a quarter million miles and make it look nearly new. It helps to have a ready supply of donor cars at the various pick & pull yards nearby. The hardest part to find was the airbag itself in the right color which some knucklehead had not yet tried to pry out, thus marring it up. Once I found that the rest of the pieces could come from essentially any W124 with an installed passenger airbag.

I also installed a center console storage box - again the right color - which will compensate for the loss of the glove box somewhat. I took the pieces from three different cars to get a complete unit. Even still, I had to reglue the wood strips back together.

I intend to do a complete write-up on the project. I took hundreds of pictures and I need to simple sort through them, add comments, and write instructions.

I next want to look into retrofitting a driver's airbag in my 85' 300SD. Why? I don't know, I guess I just like playing with Lego's.

pawoSD · #6 07-05-2009, 11:29 AM

Quote:

Originally Posted by Skid Row Joe

So, explain why?

Because they are unnecessary. In many cases they cause more injury then assistance. My wife is small and sits close to the steering wheel, she'd probably be injured pretty good if it went off. Stuff like that. It probably wouldn't affect me much as I am taller....people have even suffocated from them before.

The MB safety cell and seatbelts provides excellent protection.

pawoSD · #7 07-05-2009, 11:32 AM

Quote:

Originally Posted by pwogaman

I could say I did it for the insurance price break - of which there will be a slight one, but that would just be an excuse. I did it because I could and I really enjoy working on these cars. I love the way you can take a car with nearly a quarter million miles and make it look nearly new. It helps to have a ready supply of donor cars at the various pick & pull yards nearby. The hardest part to find was the airbag itself in the right color which some knucklehead had not yet tried to pry out, thus marring it up. Once I found that the rest of the pieces could come from essentially any W124 with an installed passenger airbag.

I also installed a center console storage box - again the right color - which will compensate for the loss of the glove box somewhat. I took the pieces from three different cars to get a complete unit. Even still, I had to reglue the wood strips back together.

I intend to do a complete write-up on the project. I took hundreds of pictures and I need to simple sort through them, add comments, and write instructions.

I next want to look into retrofitting a driver's airbag in my 85' 300SD. Why? I don't know, I guess I just like playing with Lego's.

I completely understand. I do projects like that on my cars too, just because it is enjoyable and interesting.

Everyone I know has a hard time understanding....

compu_85 · #8 08-19-2012, 06:49 PM

Quote:

Originally Posted by pawoSD

Because they are unnecessary. In many cases they cause more injury then assistance. My wife is small and sits close to the steering wheel, she'd probably be injured pretty good if it went off. Stuff like that. It probably wouldn't affect me much as I am taller....people have even suffocated from them before.

I'm trying to find a link, but I once read an article from I think Auto Motor und Sport where they crashed two W124s into each other at 35 mph, one with aibags one without. They found for the driver it was a huge help as the non airbag driver hit the steering wheel. The differences for the passenger were not as great.

I'll keep my airbags.

-J