Guide to repair NSS and relay on Auto Saloons

[awg (tony)]

On my 420G, and other older auto saloons, is a Neutral Safety Switch, with associated relay, that locks out start in gear and activates Reverse Lights.

Eventually yours will stop working, and you will be in a world of hurt, until you read this.

as far as I know, there is no replacement available for the NSS.
(please alert me if this is incorrect)

Luckily, they can be dismantled and (usually) repaired

I have dismantled NSS from various other vehicles and repaired them, they are hundreds of $ new.

wiil edit in pics shortly, and a guide to diagnose & replace relay

• mark the position of bracket relative to switch…its actually better to take the whole bracket out first in this case

• note the wire colors, carefully pry back the tabs and remove the guts
  

the inside is badly affected by copper oxidisation

clean with a mild solvent and light wire wool,doesnt that look better!

bolt it back, and be glad you marked it before, as you will be able to avoid the FSM procedure of adjusting it

more later folks

[Breen60 (Paul Breen)]

Hi Tony, are we talking BW DG series autos? Paul

[awg (tony)]

@Breen60

Hi Tony, are we talking BW DG series autos? Paul

The case study will be the cable operated trans, with a BW8, but the principles apply to (probably) almost any auto vehicle. I have repaired these for many makes and models.

S3 XJ has a modern style, costing +$200…these can also be repaired

[awg (tony)]

@awg

more later folks

Update on NSS availability

It seems the NSS for BW12, 35, 65 is the same part, and available new. It is cheap. They have a different method of operation, and the switch is simpler

For BW8 the part is NLA
For DG the part is NLA

These can be obtained via Ebay, as used or NOS

• be aware I saw BW12-35 NSS advertised as fitting older models, I believe this is incorrect

how to diagnose a fault in NSS

The issue will be no crank, and possibly no reverse lights

The NSS does 2 things…this can be confusing!

1. provide a path to earth for the Inhibitor Relay to operate
2. provide +12V to the Reverse lights

In the case of the 420G, the Start relay is hidden in a truely weird spot, and has a one line mention in the FSM…its up under the passenger side glovebox, hanging like a vampire bat

This relay has a tendency to drop some voltage and cause a “no crank” situation, even if the NSS is working!

So to test the entire circuit, which includes ignition switch, starter button, NSS switch, relay…

pull the 2 fat wires from the relay, and bridge them. If your car cranks upon pressing the starter button, the problem is in the relay or NSS

gently flatten the crimps…at this point you may blaspheme…believe it or not, I did get this working again, but decided to replace it with a regular Bosch, as the originals are NLA

my 420G guru told me these relays “always fail” and he bridged the relays out.
Your vehicle will start in any gear if you do this

part 3 on relay replacement options/ wiring to come

[awg (tony)]

@awg

part 3 on relay replacement options/ wiring to come

The relay shown (6RA 33232E) is NLA but another Lucas or a Bosch can be re-wired.

The circuit NSS provides an earth for the relay, via a thin wire.
The 2 thick wires go the starter solenoid from the starter button, via ignition switch

here is comprehensive info to rewire Lucas relays

Lucas-relays%20etc.pdf

to rewire that relay to a Bosch;

C2 = White/Blue = power in (from push start button)

C1= White/Red = switched power out (to solenoid)

(both thick cloth wires)

W1 = green & black = earth via inhibitor switch (thin plastic wire)

Obtain 4 pin Bosch, double male spade piggy-back terminal, and a female spade.

Make a short jumper using the double male, and attach across pins 30 and 86.
Pin 30 is “power in” …attach white & blue to male spade

push red & white onto pin 87 (power out)
push green and black onto pin 85 (switch to earth)