84 SD Question on ignition. - PeachParts Mercedes-Benz Forum

Clemson88 · #1 07-26-2017, 03:04 PM

The best I can tell I've finished the undercarriage and engine bay work on installing the om617.xxx into the 85 380 SE body. I moved to the interior restoration/renovation this morning and started with the ignition switch assembly installation.

Note the small junction box on the ignition switch assembly, center photo. I have two different pairs of wires on the two different bodies and switches and am in the process of installing the diesel switch in the gas body.

Can anyone/someone tell me what the function of this wiring is please?

Alec300SD · #2 07-26-2017, 04:13 PM

Switch for ignition key warning buzzer.

SD Blue · #3 07-26-2017, 04:17 PM

Did the 300SD have a factory alarm system?
That would be my first guess but failed to find it on the wiring diagrams in the FSM.

Alec300SD · #4 07-26-2017, 04:24 PM

Quote:

Originally Posted by SD Blue

Did the 300SD have a factory alarm system?
That would be my first guess but failed to find it on the wiring diagrams in the FSM.

Wiring diagram is kind of buried in the FSM.
Here's a link: https://www.startekinfo.com/StarTek/outside/12253/program/Chassis/54-410.pdf

Clemson88 · #5 07-26-2017, 06:00 PM

Quote:

Originally Posted by SD Blue

Did the 300SD have a factory alarm system?
That would be my first guess but failed to find it on the wiring diagrams in the FSM.

Yes, the SD has a factory alarm. The SE has one too. The SE ignition doesn't accommodate the vac shutoff so I had to install the SD switch assembly.

The issue I'm running into here is that the SE body has two of those two prong connectors. Oh, and thank for the good information. I'll dig through the FSM and sort this out.

Clemson88 · #6 07-26-2017, 06:07 PM

Quote:

Originally Posted by Alec300SD

Wiring diagram is kind of buried in the FSM.
Here's a link: https://www.startekinfo.com/StarTek/outside/12253/program/Chassis/54-410.pdf

Would the belt and door warning be the ID of those two-two prong connectors? In other words, if I just didn't want to listen to warning I could leave these unconnected?

I always buckle my seat belt and I can tell when the door is ajar. I also use the key to lock the door so that isn't an issue either. For the SD I have a new tumbler from the dealership and four keys.

I had planned to buy a new tumbler for the SE body and four keys for that too. I quit taking the key out of the ignition unless I have the car parked in public so the tumblers will remain fresh for a long, long time. Yes, I went through the madness of drilling the tumblers out a few years ago.

Alec300SD · #7 07-26-2017, 09:17 PM

No, if you leave it unplugged you will only disable the key-in-ignition warning.

The seatbelt warning and headlight warning will still work.
Just tested this out.

Clemson88 · #8 07-26-2017, 11:07 PM

Quote:

Originally Posted by Alec300SD

No, if you leave it unplugged you will only disable the key-in-ignition warning.

The seatbelt warning and headlight warning will still work.
Just tested this out.

I can live with the warnings. Do you have any idea what the other connection on the SE ignition is?

Thank you for all your help.

Alec300SD · #9 07-27-2017, 03:07 AM

The .75 RD and .75 RD/GN wires shown on your photo are for the "Key Warning Switch"
at the center of the top of pdf page 25 on the Circuit Diagram Index of the ETM (Electrical Troubleshooting Manual) link (Page 118/1).

What are the colors and size of the wires on the other connector on the 85 380 SE?
I might be able to figure out what the second connector plugs into...even though I've not wrenched on a MB gasser lately.

Maxbumpo · #10 07-27-2017, 10:42 AM

Hmm, is that also input for the warning when you leave the headlights on but remove the ignition key? That's a useful feature - saves you from draining the battery.

Clemson88 · #11 07-27-2017, 12:09 PM

Much obliged to you, gentlemen. I got rough with the 2 connector/2pin switch on the SE steering lock with a pair of needle-nose pliers and it yielded to my judgement. It came off without incident so I'm planning on installing it on the SD lock and suggest that it will most likely work as was designed.

For the record, the two wires which exist on the SE body that are not on the SD body are brown/white and brown. It appears to the uneducated, the switch serves as a ground for another warning component. Though I could have lived without the warning systems on doors, key and other annoying features I am delighted to keep with my theme of original wiring/equipment and functions on this project.

I will post photos of these alterations if anyone is interested and can't tell what we've done from the conversations. Thank you all, again.

Alec300SD · #12 07-27-2017, 06:28 PM

Quote:

Originally Posted by Maxbumpo

Hmm, is that also input for the warning when you leave the headlights on but remove the ignition key? That's a useful feature - saves you from draining the battery.

No, the input is just for warning you that the key was left in the ingition (when the driver's door is ajar).
Disconnecting that input will not affect the other inputs that cause the buzzer to activate (headlights left on, and driver's seatbelt not buckled).

The warning buzzer contiuously sounds when you leave the headlights/parking lights on (and the driver's door is ajar), regardless of whether or not the key is in the ignition.
The warning buzzer sounds (and then times out after about a half minute) as a reminder to fasten the driver's seatbelt when the ignition key is turned to the run position.

Quote:

Originally Posted by Clemson88

Much obliged to you, gentlemen. I got rough with the 2 connector/2pin switch on the SE steering lock with a pair of needle-nose pliers and it yielded to my judgement. It came off without incident so I'm planning on installing it on the SD lock and suggest that it will most likely work as was designed.

For the record, the two wires which exist on the SE body that are not on the SD body are brown/white and brown. It appears to the uneducated, the switch serves as a ground for another warning component. Though I could have lived without the warning systems on doors, key and other annoying features I am delighted to keep with my theme of original wiring/equipment and functions on this project.

I will post photos of these alterations if anyone is interested and can't tell what we've done from the conversations. Thank you all, again.

From my read of the ETM, the two prong underdash connector with brown/white and brown wires is part of the parking brake warning lamp indicator circuit.
It should plug into the parking brake switch on the left side of the DS footwell.
It plugs in from above.

Many owners simply unplug the DS seatbelt warning switch (right side of driver's seat) if they find the warning buzzer to be an annoyance.
The warning buzzer with still activate if you leave the headlights on.

If you don't want the buzzer to sound at all, you need to unplug the warning buzzer relay from its socket.
Full functionality can be easily restored at a later time by plugging the relay back into its socket.

I think I've read of mods being done to the relay to give different sound outputs that are less obnoxious.