I always start with a disclaimer that this is my fist Volvo, and my car came in boxes, so I'm slowly figuring out all the parts. Tonight's question is an oldie but a goodie. I've found the answer, but I don't get it, so I'm including pics and asking for clarification.

QUESTION: when converting from BW35 to M40 or M41 how does one bypass the neutral safety switch?

I've found the posts that say to jump the two blue wires, BUT I have three and none go to the starter. I've included a pic of the body harness on my car that seems to be the neutral safety switch harness and a pic of the NS switch, which was in a box. Since nothing was hooked up, I've got three blue wires and I don't know how they went together originally.

On the switch I have blue wire A, and blue wire B. On the car I have a connector with a blue wire. Do I just connect the blue wire on the body harness to the starter? I'm thinking "no." Do I have to keep the NS switch on the car? I hope not because mine looks pretty bad.

Hi John jrv6a,

I revised the image links here for others to see. Unsure the second image you posted.

I see in your post history you own a 1973 Volvo 145.

I have the Haynes 1974 imprint 'Volvo 142, 144 & 145' service manual here. Uses the same schematic as the factory green Volvo service manuals.

I'll guess with D-Jetronic engine control? It does not matter whether carbed or injected as the circuit appears the same using BW35.

The contact switch on BW35 serves as neutral safety switch (Park, Neutral) and also powers the reverse light relay (DPDT) to close when the gear lever is in reverse, closing that circuit to power the relay, and in turn, powering the reverse lights.

One of the blue wires, then, connects to the starter switch main relay, to power it, so the relay closes, and powers the start motor solenoid.

The other blue wire, as aforementioned, power the reverse light relay.

And now, to fight, with BrickPix.

Wire color legend (Yes, I know, too wide for the column):



Images from the Haynes 1974 imprint 'Volvo 142, 144 & 145'. Using two schematic / legend labeled D6 and D7.

Schematic D6 Legend & Schematic (Page 196 & 197). Diagram supports carbed 140 series after 1970.
Displays the M40/M41 and BW35 schematic.

Legend:



M40 / M41 & BW35 Schematic:




Schematic D7 Legend & Schematic (Page 198 & 199). Diagram supports carbed 140 series after 1970.
Displays the BW35 schematic. Reference D6 for M40 / M41 wiring schematic.

Legend:



BW35 Schematic. Appears same as on the D6 diagram.





Your other image I found on BrickPix.


The Oz Volvo Technical Archive contains 140 series info scanned to PDF. Save the PDF files to your computer.

https://ozvolvo.org/archive/

Appears to have hybrid 1800 / 140 manuals as 1972-1973 and also 1974 info.



Contains all 164 manuals for all years in English. The scans are unclear when you get to the wiring diagrams. At least for 1973 TP 10778. Was going to reference these for you. Maybe 140 series green manuals are scanned to PDF someplace.
http://www.240.se/litteratur/service100.htm


Once I click SUBMIT MESSAGE, well, and mistakes remain.

Hope that helps you.

Want a 142 and a 164 both with M41 and M410, respectively.

And a garage to care for them and keep them out of the weather.

South Dakota? Better back to WA-state. Maybe MI-state. Like Houghton on the UP.

This Technical Writer can't get no remote or other job ain't no way. Ain't no way.

Thanks for all the help. Usually I have no prob adding pics. It figures the one time I put "pics" in the title there'd be a glitch. Here's the other pic. Maybe it will help someone else in the future.

I'm pretty sure you do just connect the blue wire in the connector to the starter trigger pole.

Use a test light to confirm that the blue wire in the connector gets power ONLY when you turn the key to the start position and then goes out when the key is in any other position.

--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com