Jeep Needs a Neutral Safety Switch

Oh I love it.

After hitting a deer, doing the spark plugs, fixing a coolant leak and the suspension, the neutral safety switch goes on the jeep. Of course it’s not an easy fix, I was really hoping it was the starter relay. I was at autozone at 8am this morning buying a new relay and they sold me the wrong one (for $6 I am not even going to bother returning it) and then when I got to wawa to fix the jeep it passed the voltage test on the battery, which was the other quick fix I was hoping for. I ended up opening the engine electrical panel to see it was corroded as hell, so that’s another fun possibility but I was able to swap the relays from the fuel system to the ignition system and I still couldn’t get the starter to move. I considered jumping the battery to the starter but could I replace the starter in the wawa parking lot? Nope. I figured it was easier to call AAA and get it towed home.

The neutral safety switch on a jeep is a piece of work. Rather than KISS it together with a contact which is made when you’re in the proper gear (Toyota) on the shifter itself, Chrysler saw fit to put a gear in the shifter which moves a linkage which sweeps a rotor to the proper set of contacts. Of course the gear gets worn out, or the rotor wears down, or the contacts get corroded because the car is a rust bucket and you really start to question your sanity for trusting automatic transmissions or Chrysler to build anything right. Replacing it involves not only getting the part for $400 but then dicking with it endlessly to ensure the contacts line up and the travel is correct. Apparently there’s a third party one for $120 which “doesn’t require alignment!” but I’m guessing it simply feeds the correct signal to the harness rather than doing any real work.

After putting all the various relays and wires back into the correct positions, I started googling and found out that this affects the entire line of jeeps from 1991 to 1998. It’s a known problem.

Thankfully, someone helpfully posted the neutral safety switch schematic to the internet. While they didn’t tell you that the diagnostic port for this is next to the oil filter, you’re pretty much led to look there. The insinuation is to jumper the pins and forget about it. Now the bad part – unlike real service manuals which indicate the binary “connected”, “do not connect” and “doesn’t care”, I don’t see any “do not connects” marked in that diagram. Anyone know if it’s bad to leave this jumpered?

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