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Discussion Starter #1
Need a little help here. I have a 1978 280CE and I installed a new neutral safety switch.

The problem is that as I removed the wire harness plug it crumbled away and I lost track of what color wire went to which terminal on the switch.

I have a replacement harness section from the salvage yard to fix the broken plug but the wires are different color codes, so that doesn't help me match things up.

Does anyone have a schematic or otherwise know what color wire goes to what terminal on the NSS for a 78 280CE?

Thanks.
 

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I'm having this exact problem right now. The harness part of it is destroyed, and all I'm left with is 4 wires, two of which have rods and two of which are bare.

I'm writing this to bump your thread, and please let me know if you've found a solution.


Need a little help here. I have a 1978 280CE and I installed a new neutral safety switch.

The problem is that as I removed the wire harness plug it crumbled away and I lost track of what color wire went to which terminal on the switch.

I have a replacement harness section from the salvage yard to fix the broken plug but the wires are different color codes, so that doesn't help me match things up.

Does anyone have a schematic or otherwise know what color wire goes to what terminal on the NSS for a 78 280CE?

Thanks.
 

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Discussion Starter #4 (Edited)
I got my hands on a W123 service manual with a specific wiring diagram for the '78-'79 280CE, similar to "matthew's."

Here goes my best shot at describing it. I will try to post a picture of the wiring diagram as well. The manual lists the switch pins in the following order with the corresposnding circuit number which I'll note (in parentheses).
Pin 3 (50): Brown/yellow wire from AC/starter relay.
Pin 1 (81): Black/red/yellow wire from the kickdown switch.
Pin 2 (81a): Grey/green wire leads to pin #6 on the harness connector.
Pin 4 (50): Brown wire is the ground.

I'll be digging into my 280CE around Wedensday. I'm replacing the end of my smashed harness with that from another 123 donor car. Let me know if you settle your harness issues before that. I'll post my outcome if it helps. Right now I only have start in neutral and no kickdown, so I got something crossed somewhere.
 

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I got my hands on a W123 service manual with a specific wiring diagram for the '78-'79 280CE, similar to "matthew's."

Here goes my best shot at describing it. I will try to post a picture of the wiring diagram as well. The manual lists the switch pins in the following order with the corresposnding circuit number which I'll note (in parentheses).
Pin 3 (50): Brown/yellow wire from AC/starter relay.
Pin 1 (81): Black/red/yellow wire from the kickdown switch.
Pin 2 (81a): Grey/green wire leads to pin #6 on the harness connector.
Pin 4 (50): Brown wire is the ground.

I'll be digging into my 280CE around Wedensday. I'm replacing the end of my smashed harness with that from another 123 donor car. Let me know if you settle your harness issues before that. I'll post my outcome if it helps. Right now I only have start in neutral and no kickdown, so I got something crossed somewhere.
I'm assuming the order would be the same for a 240D?
 

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Discussion Starter #6
I'm not near my pc so I have to look at Matthew's link on my phone, so I can't really see it. It looks to be similar to the 123 chassis service manual. Thanks for providing.

Diesels use different thickness starter circuit wires due to the higher electrical loads. My book lists the 240D wiring for the below years. I bet subsequent years are similar since the 240D didn't change much.

1978/1979/1980 model year:
Pin 3: purple/white
Pin 1: black/yelllow/red
Pin 2: grey/yellow
Pin 4: purple
 

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I'm not near my pc so I have to look at Matthew's link on my phone, so I can't really see it. It looks to be similar to the 123 chassis service manual. Thanks for providing.

Diesels use different thickness starter circuit wires due to the higher electrical loads. My book lists the 240D wiring for the below years. I bet subsequent years are similar since the 240D didn't change much.

1978/1979/1980 model year:
Pin 3: purple/white
Pin 1: black/yelllow/red
Pin 2: grey/yellow
Pin 4: purple
Thanks for this!
 

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Wiring worked. I ran into some trouble on my project though: the shaft that the NSS fits into, the one for the shifter linkage, snapped off along with the shifter linkage arm fastener. Anyone know what this part is called and if its replaceable?
 
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