December-2009,-Indiana

AW4 Neutral Start Switch Rebuild

Is your XJ (or even Toyota) having trouble starting?  Or maybe your backup lamps just don’t work.  You can either spend hundred of dollars getting a replacement neutral start switch (aka Park/Neutral Position switch) or you can spend a few dollars in supplies and about twenty minutes and fix it yourself.

You will need the following items:

12mm wrench or socket
7/8″ wrench or socket
#2 phillips screwdriver
Standard screwdriver
Contact cleaner
Dielectric grease
Forceps or small needlenose pliers
Dental pick or other small sharp object
Steel wool and/or brass wire brush
Multimeter

You start by removing your Neutral Start Switch (NSS).  The NSS is located on the passenger side of the transmission just behind the bellhousing area.  To remove it you simple use your standard screwdriver to bend the tabs (not visible in the below photo) that secure the large nut flat and remove this nut.  Then remove the 12mm bolt on the top of the NSS and simply pull it straight outward, you may need to use screwdrivers to pry it outward if it is giving you trouble.

NSS Installed, click to see it larger
NSS Installed, click to see it larger

After you’ve freed up the bottom end you will need to disconnect the wiring harness.  The wiring harness connector is located near the passenger side rear of the cylinder head, it is the only black connector that looks like the photograph below (there is a grey one that is a lot like it, ignore that one).  To separate the two halves of the connectors pull up on the tab (do not down like usual) and pull, then feed the wiring harness down and remove the switch from the bottom of the vehicle.  You may have to cut some zip ties or other clips free in order to remove it.

NSS Connctor, click to see it larger
NSS Connctor, click to see it larger

Now that you have the switch out remove the screws from the back of the NSS and set them aside.

Back of NSS, click to see it larger
Back of NSS, click to see it larger

Next pry the two halves of the NSS apart being careful not to lose any parts that may fall out.  What you should see is a bunch of old dirty dielectric grease and some cruddy looking copper contacts.

Switch apart, click to see it larger
Switch apart, click to see it larger

First remove the two contacts from the switch arm and the springs behind them.  I use a pair of forceps to gently grasp the contacts and pull them free, then I use a dental pick type tool to hook the small springs and pull those dirty things out.

Switch arm contacts, click to see it largerSwitch arm contacts, click to see it larger

After getting all the pieces out spray everything down with contact cleaner (brake cleaner will also work) and make sure to get all the old caked on dielectric grease out.  After doing that take your steel wool or brass brush and polish the top of those copper contacts up.

NSS Rebuild - 08Inside of switch cleaned up, click to see it larger

Now take your dielectric grease and lightly coat the switch arm and switch housing, be careful not to use so much that it gums everything up then start putting it back together.  Start by inserting the small springs into their holes in the switch arm then lay the contacts over them.  Now gently lay the back of the switch over the switch arm being careful to make sure that the switch arm contacts do not come out of position.

NSS Rebuild - 09
Switch arm contacts, click to see it larger

Then flip the switch over and put the aluminum switch over in place and secure the four bottom screws (leaving the screws that secure the wire harness out).  Now put the wiring harness bracket into position, take care to make sure the switch vent is properly tucked into the convoluted tubing.

NSS harness, , click to see it larger
NSS harness, click to see it larger

Now put the remaining two screws in and you’re done, you’ve now fixed your neutral start switch and are ready to install it.

Start by placing the switch into position and putting the 7/8″ nut on, you don’t want to over tighten this nut as the switch arm does still have to move.  Next put the 12mm bolt in and run it down to finger tight, then back it off one half turn.  You will now need to adjust the NSS.  Take your multimeter and make sure there is continuity across these terminals for each shifter position.

With the shifter in Park you should have continuity between terminals B and C.

Shifter in Neutral, click to see it larger
Shifter in Park, click to see it larger

With the shifter in Reverse you should have continuity between terminals A and E.

Shifter in reverse, click to see it larger
Shifter in reverse, click to see it larger

With the shiver in Neutral you should have continuity between terminals B and C (the same as in Park).

Shifter in Neutral, click to see it larger
Shifter in Neutral, click to see it larger

With the shifter in Drive you should not have continuity between any terminals.

Shifter in Drive, click to see it larger
Shifter in Drive, click to see it larger

With the shifter in Third you should have continuity between terminals A and G.

Shifter in Third, click to see it larger
Shifter in Third, click to see it larger

And finally with the shifter in First/Second you should have continuity between terminals A and H.

Shifter in First/Second, click to see it larger
Shifter in First/Second, click to see it larger

Now tighten up the 12mm set bolt and double-check the switch alignment when you run the shifter back up into Park.  Now re-route the cable back up the firewall and plug the connector in.

All done!