Neutral Safety Switch Problems
Updated August 4, 2006
I turn the key but the engine won't start and the starter won't turn.
There's a good chance it's the neutral safety switch. This is a switch located in the shifter mechanism that keeps the engine from starting if the transmission isn't in park or neutral.
First, you might start the truck by holding the shifter for the transmission hard to the left (toward your leg) while in neutral or park. You must constantly hold it while trying to crank the starter. Once started, release the shifter.
There are no adjustments for this switch. It is a simple steel ball type switch in a rectangular housing that is held with two screws to the shifter mechanism. The screws can loosen up so the switch gets out of alignment. The switch's ball bearing surface wears out causing poor mechanical contact with the shifter.
You can bypass the switch if you can identify the two wires. There are 5 wires in total, two for the reverse switch, two for the neutral safety switch and one for the internal light. The neutral safety switch is toward the front of the truck (shifter). If you bypass, then the truck can be started in any transmission position so a real potential safety hazard. These are military style connectors so rig a 6 inch wire with two military ends, I believe one male and one female ... could be wrong.
You can "jumper" the neutral safety switch. There's a velcro "pouch" under the gear shifter accessible from underneath the truck directly below the shifter. Open the velcro pouch from under the truck & you'll see all the wires. Install a piece of 8" long wire as a JUMPER around the neutral safety switch by connecting the jumper wire to each side of the switch. Look in the service & parts manual to confirm the color of the wires (the wires I jumped on my 97.5 were blue/white and brown, but your model year may be different). Be careful after you install the jumper because now your truck will start in any gear.
To pull the shifter out of the truck really takes two people. The person inside the cab holds the Allen screws holding the shifter mounting plate while the person under the truck removes the nuts. The hardest part is removing the cable to the ignition lock mechanism. This requires the ignition to be ON (i.e.: have the transmission in Park and T-case in High) prior to disconnecting the levers. Chock the wheels, and do not disconnect the battery until you get past this step to give you cable length to pull the metal ball on the cable out of the shifter housing using a curved needle-nose pliers.
Otherwise you have to disconnect 5 wires, disconnect the adjustable rods to the shifters (do not loose the wave washers or the shifter levers will rattle), remove 4 nuts in very awkward positions and pull out the shifter with its two boots on. Be careful that you don't cut the rubber boot while removing the lock cable. This job takes around 2 to 3 hours due to the tight spaces.
I've been told that you can use a backup light switch to replace the neutral safety switch which costs a lot more. You have to modify the backup switch to work. The top is the original neutral safety switch. Below it is the modified backup switch.