If you hold the key over, and jiggle the shifter in park or neutral and it starts, it's your NSS. http://bc4x4.com/tech/2010/jeep-neut...ty-switch-nss/


What freedgr said in post 12 is pretty important. If you hold the key over on start, then jiggle the shifter around park and neutral, does it go? (move the shifter while holding the key, good and over on start)

My NSS is gummy. Parked hot it always starts in the AM. If I just move the Jeep while it's cold the NSS will stick and I'll need to jiggle the shifter. (Actually I know now to just push it forward on mine)

But it clicks? See here: Battery gasses have a nasty habit of helping a thin, hard crust form on the bat post's and clamps. They can look pretty good, but that micro-thin layer is a surprisingly good insulator. SHINNY! Lead is what you want. I use a pocket knife, (gently), for the insides of the clamps. For the posts I might use one of those post cleaner wire brushes, but still scrape it with a blade. If you have a condition where you have power, (dash lights ect.), then when you hit it power goes out altogether, that's a common result of a layer of oxidization there. Btw, a half *** connection could be expected to get hot during cranking, or while it's trying. Cleaning those is something to do now and then anyway, so if you are having starting problems, you might want to make sure you have bare lead on lead. Might save you some grief!

 

Assuming you've checked the fuses in the PDC as suggested earlier,
There is a start relay in the PDC that switches power to that small wire. (That wire activates the starter solenoid) The positive coil terminal of that relay is triggered by the ignition switch, the negative runs to ground through the NSS.
See if the relay is operating when you turn the key to start. Might try swapping the relay with another. If the relay isn't operating, start tracing your way back to the ignition switch.

 

Evening Chuck...Yea underutilized, the amount of info that can be gotten right at that relay socket. IS the NSS grounding it? IS the ignition juicing it? Sacking out.

Btw OP, it has two directions sort of like a cross. It gets juice at the feet it shoot's out the head to the starter solonoid. It does that when the ignition shoots juice in one hand, that is grounded my the NSS on the other hand. (that "hand to hand" actually makes a little magnet/solonoid, that is connecting the real current)


...........-- <out
NSS> l -- l < Ign

............l < in

The SPDT relay, (single pole, double through), will route power from the bottom to the middle until it's energized, (and grounded), at which time it will divert that power to the top. That would be the starter solonoid in this case.

 

Starts when post on starter are jumped. When testing no current at small wire on starter when keys in run position.

 

Exactly same thing happened to me before with my 91. A new battery and battery cables solved that problem for me, but I always thought the problem is caused by the loose battery connections on either positive or negative side. Put a wrench under the neg or pos connector on the battery and apply pressure upwards with a 30 degrees angle. It really tightens the cables there, and might just be your solution.

If something doesn't work when it's warmed up, it usually (not always) is because that thing has a crack or a gap on it. The crack expands with the heat and the unit starts to malfunction.

 

Fuse #19, 10 Amp, in the Junction Block powers the control coil of the starter relay. If this fuse is blown the starter relay won't pull in.

 

Wow, I go to bed defeated, and I wake up to all these replies! Thanks guys!

OK, I'll try to address as many of these as I can....

1. First, it does NOT start when I jiggle the shifter in Park or Neutral.

2. As Red mentioned, the Reverse lights do not come on. I never noticed that before, but now that I checked, they don't work. Could I test the appropriate contacts on the NSS plug for Reverse to see if the switch is picking up that signal from the tranny? Also, even if that part of the NSS is shotty, would that really affect its ability to start if I'm getting good continuity between 'B' and 'C' when its in Park and Neutral?

3. Ken, thanks for the suggestion, I checked the #19 fuse and it is good.

I also tried jumping the battery from my newer car, which has a great battery, no luck there. When I attempt to start it, I have all the interior lights and headlights that I should, as well, none of the lights dim or cut out when I try to key it on. So that has me feeling like the battery is fine.

 

Here's the Transmission Range Sensor (NSS) connector pinouts.

To NSS:



To TCM:



To check the reverse lights jump pins 3/A to 6/E on the 'To TCM' connector with the ignition switch to RUN.

 

Thought I'd trough this in for good measure.

It's testing from on the connector that goes to the TRS/NSS:

PARK/NEUTRAL POSITION SWITCH TESTING

Test switch continuity with an ohmmeter. Disconnect the TRS/NSS connector and check continuity at the connector terminal positions to the TRS/NSS and in the gear ranges. Switch continuity should be as follows:

• Continuity should exist between terminals B and C with the transmission in Park and Neutral only.

• Continuity should exist between terminals A and E with the transmission in Reverse.

• Continuity should exist between terminals A and G with the transmission in third gear.

• Continuity should exist between terminals A and H with the transmission in first and/or second gear.

• Continuity should not exist in D position.

 

Well I definitely don't have continuity between 'A' and 'E' when the transmission is in reverse. But I do have continuity between 'B' and 'C' when its in Park and Neutral. So that should rule out the NSS causing the failure to crank, right?

 

UPDATE- just to humor myself, I followed that tutorial and pulled the NSS, cleaned it up real well, and reinstalled it. I get continuity between 'B' and 'C' when the transmission is in Park and Neutral..... but still will not start!

What could be wrong?

 

Did cleaning the NSS get the reverse lights to work?

 

Yes. I am kinda happy about that. It was a gummy horrible mess inside!

 

You may want to check the ground connections at ground G106, located on the left inner fender near the PCM. The pic shows one of the circuits grounded here is the "Transmission Range Sensor", aka NSS, P/N switch that connects the Start Relay control coil ground circuit to this ground.

You may want to remove the sheet metal screws and clean all the terminal ends and resecure them with new screws.

 

Thanks Ken! Headed to work now, so I'll have to try it in the morning, but I have already jumped the 'B' and 'C' terminals on the main harness plug for the NSS, essentially bypassing that component. I'm also leaning toward the ignition switch right now.

If I pull the ignition, is there a procedure for checking it for function?