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Unread 01-27-2012, 09:51 AM   #1
inliner6
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1996 XJ Cherokee 
 
Join Date: Jan 2012
Location: Panama City Beach, FL
Posts: 9
neutral safety switch diagnostics

i think my neutral safety switch is going out (well has gone out). how exactly do you determine if it has? what do i need? etc... heres y i think its dead: i put the key in the ignition, turn it to ON and i get juice from the battery to run the A/C, radio, power windows, etc. i turn the key from ON to START and i get nothing whatsoever. the problem used to be intermittent but now its everytime.
i have replaced: key lock cylinder, ignition switch, starter motor and silenoid, battery cable connectors, the battery has plenty of juice and the cables are fine.
could it be something else?

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Unread 01-27-2012, 11:26 AM   #2
gunner44
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1997 ZJ 
 
Join Date: Aug 2011
Location: Petoskey, Michigan
Posts: 641
This will give you a over view of the operation when the key is turned. Assume the charging system works because lights are working. Next, Starting system, that has in it the Ignition switch, Engine starter motor relay in the power distribution center, Park/neutral position switch, Motor and solenoid. This is through fuse 8 in the PDC. I would also check the Auto shutdown Relay in PDC. The security system is not armed is it. --- Got to go, will check back, Get at least a Haynes book at the parts store.

IGNITION SWITCH (KEY-ON) MODE
This is an Open Loop mode. When the fuel system
is activated by the ignition switch, the following
actions occur:
The powertrain control module (PCM) pre-positions
the idle air control (IAC) motor.
The PCM determines atmospheric air pressure
from the MAP sensor input to determine basic fuel
strategy.
The PCM monitors the engine coolant temperature
sensor input. The PCM modifies fuel strategy
based on this input.
Intake manifold air temperature sensor input is
monitored.

Throttle position sensor (TPS) is monitored.
The auto shutdown (ASD) relay is energized by
the PCM for approximately three seconds.
The fuel pump is energized through the fuel
pump relay by the PCM. The fuel pump will operate
for approximately three seconds unless the engine is
operating or the starter motor is engaged.
The O2S sensor heater element is energized via
the ASD relay. The O2S sensor input is not used by
the PCM to calibrate air-fuel ratio during this mode
of operation.
ENGINE START-UP MODE
This is an Open Loop mode. The following actions
occur when the starter motor is engaged.
The powertrain control module (PCM) receives
inputs from:
Battery voltage
Engine coolant temperature sensor
Crankshaft position sensor
Intake manifold air temperature sensor
Manifold absolute pressure (MAP) sensor
Throttle position sensor (TPS)
Starter motor relay
Camshaft position sensor signal
The PCM monitors the crankshaft position sensor.
If the PCM does not receive a crankshaft position
sensor signal within 3 seconds of cranking the
engine, it will shut down the fuel injection system.
The fuel pump is activated by the PCM through
the fuel pump relay.
Voltage is applied to the fuel injectors with the
ASD relay via the PCM. The PCM will then control
the injection sequence and injector pulse width by
turning the ground circuit to each individual injector
on and off.
The PCM determines the proper ignition timing
according to input received from the crankshaft position
sensor.
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Unread 01-27-2012, 06:33 PM   #3
leftlanetruckin
XJ on 37's
 
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1998 XJ Cherokee 
 
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Before replacing all those parts, did you ever try to start it by either wiggling the shifter, or putting the shifter in neutral?
Here is the wiring diagram for the XJ NSS plug:
nss.gif
You can jumper the plug and make it start, and that is free
Do your reverse lights work OK? Another sign of a bad NSS.

Martin
__________________
1998 XJ on 37's.JK Rubi axles with chromo shafts and ctm's, 4:1 transfer case, etc etc etc.The Cherylkee....
2003 Range Rover HSE, 4.4 Quad Cam.
1998 Range Rover 4.6 HSE
2000 4.7 4WD WJ with a rebuilt motor.
4.3/700r4/new frame buildup (YJ)....
http://www.jeepforum.com/forum/f12/swap-offically-underway-324622/

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Unread 01-27-2012, 09:36 PM   #4
inliner6
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1996 XJ Cherokee 
 
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Location: Panama City Beach, FL
Posts: 9
martin- ive tried to start it wiggling, jiggling, and through all the gears. nothing works. my reverse lights havent worked since i bought it in aug 2010. (i replaced every bulb in the jeep when i bought it)

what do you mean by 'jumper the plug'? i have the haynes manual that has the diagram you posted and i am familiar with it.

gunner- i dont have a security system of any kind. from what im reading from you and martin and others i really think its my nss... thanks

disclaimer: IF I SOUND IGNORANT AND SAY SOMETHING REALLY STUPID, UM, JUST IGNORE ME lol
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Unread 01-28-2012, 07:46 AM   #5
leftlanetruckin
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Jumper means to use a wire to connect two pins together on the plug. This will bypass the nss itself and make the ecm think it is in neutral or park, this testing the switch in a roundabout way. If it starts when you jumper the wires, it's the switch. If it still does the same thing, it isn't.

Martin
__________________
1998 XJ on 37's.JK Rubi axles with chromo shafts and ctm's, 4:1 transfer case, etc etc etc.The Cherylkee....
2003 Range Rover HSE, 4.4 Quad Cam.
1998 Range Rover 4.6 HSE
2000 4.7 4WD WJ with a rebuilt motor.
4.3/700r4/new frame buildup (YJ)....
http://www.jeepforum.com/forum/showthread.php?t=324622

Years to gain the hands on experience, and offer it freely.
Minutes to gain the knowledge from the internet, and quote it just as freely.
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Unread 01-28-2012, 08:17 AM   #6
gunner44
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1997 ZJ 
 
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Location: Petoskey, Michigan
Posts: 641
Here is another way also. You know the starter motor relay is working, right? If the Position Switch on my 97 5.2 ZJ is the same as a Safety Switch on yours, this comes from my Factory manual, this might help.

PARK/NEUTRAL POSITION SWITCH TEST
(1) Place the transmission gear selector lever in
the Park position.
(2) Disconnect and isolate the battery negative
cable.
(3) Raise and support the vehicle.
(4) Unplug the park/neutral position switch wire
harness connector.
(5) Check for continuity between the center switch
terminal and a good chassis ground. There should be
continuity. If OK, go to Step 6. If not OK, replace the
faulty switch.
(6) Move the transmission gear selector lever to
the Reverse position and check for continuity
between the center switch terminal and a good chassis
ground. There should be no continuity. If not OK,
replace the faulty switch.

IGNITION SWITCH TEST
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS,
REFER TO GROUP 8M - PASSIVE
RESTRAINT SYSTEMS BEFORE ATTEMPTING
STEERING WHEEL, STEERING COLUMN, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG
DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the steering column shrouds and
unplug the ignition switch wire harness connector.
Refer to Group 8D - Ignition Systems for the procedures.
(3) With the ignition switch in the On position,
check for continuity between the two fused B(+) terminals
of the ignition switch (terminals 1 and 7).
These are the terminals at each end of the switch
connector receptacle. There should be no continuity.
If OK, go to Step 4. If not OK, replace the faulty
switch.
(4) With the ignition switch held in the Start position,
check for continuity between the two fused B(+)
terminals of the ignition switch (terminals 1 and 7).
There should now be continuity. If not OK, replace
the faulty switch.
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Unread 01-28-2012, 10:44 AM   #7
inliner6
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@gunner- ive already replaced the ignition switch- its good. how do i check for continuity on the nss? ive got the diagram to do it. i just dont have the electronic device... what do i need?

@martin- what wires do i need to jumper if the nss is bad? looking at the diagram- make all the connections? or just cetain ones? or just one? im clueless... if its supposed to be obvious- im just not getting it
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Unread 01-28-2012, 10:45 AM   #8
inliner6
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@msrtin- B and C ?
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Unread 01-28-2012, 10:47 AM   #9
inliner6
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AAAHHH i cant type..... sorry martin
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Unread 01-28-2012, 02:07 PM   #10
leftlanetruckin
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Quote:
Originally Posted by inliner6 View Post
AAAHHH i cant type..... sorry martin
No problem mate.
You are correct, jump B and C to make the ecm think its in neutral or park. You can also back probe those terminals to see if there is continuity there too when it's in park.
Sorry for the delay, I had to replace the heater core in my big rig this morning, as the dealer I stopped at wanted 5hrs labor plus an AC evac and recharge.
Did it myself in 3hrs, and never even laid eyes on the ac evaporator etc, and cleaned and vacuumed behind all the panels. Always happens on the road when you are away from home huh?

Jump those 2 and see what happens. You dont even need to get under the rig, disconnect the battery, and so on. Takes about 3 minutes to do it, and that includes finding the wire
The plug is near the center of the motor, just to the passenger side, on top.

Martin
__________________
1998 XJ on 37's.JK Rubi axles with chromo shafts and ctm's, 4:1 transfer case, etc etc etc.The Cherylkee....
2003 Range Rover HSE, 4.4 Quad Cam.
1998 Range Rover 4.6 HSE
2000 4.7 4WD WJ with a rebuilt motor.
4.3/700r4/new frame buildup (YJ)....
http://www.jeepforum.com/forum/showthread.php?t=324622

Years to gain the hands on experience, and offer it freely.
Minutes to gain the knowledge from the internet, and quote it just as freely.
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Unread 01-29-2012, 12:00 AM   #11
inliner6
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ok sounds good. one more ignorant question... what kind of wire do i use? any particular gauge? i located that connection the other day so locating it again is no problem...

yeah im not a fan of dealer repair... $$$ ive saved literally thousands of dollars doing repairs myself. when i bought my xj i had to replace every componant almost of my liquid cooking system- thank God for DYI manuals
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Unread 01-29-2012, 02:18 PM   #12
leftlanetruckin
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Wire does not need to be anything special, 12 or 14 gauge will work fine.

Martin
__________________
1998 XJ on 37's.JK Rubi axles with chromo shafts and ctm's, 4:1 transfer case, etc etc etc.The Cherylkee....
2003 Range Rover HSE, 4.4 Quad Cam.
1998 Range Rover 4.6 HSE
2000 4.7 4WD WJ with a rebuilt motor.
4.3/700r4/new frame buildup (YJ)....
http://www.jeepforum.com/forum/showthread.php?t=324622

Years to gain the hands on experience, and offer it freely.
Minutes to gain the knowledge from the internet, and quote it just as freely.
Choose wisely!
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Unread 01-31-2012, 08:02 PM   #13
inliner6
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a 14gauge wire is too thick to fit down in the terminal to jumper it. i took a strand of stranded wire(not solid), twisted them together, and jumpered it. still nothing different. i hav not idea what im doing.
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Unread 02-14-2012, 07:56 PM   #14
inliner6
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hey guys. just got back from TN and im back on the jeep fixins. does anyone know where i could find a new neutral safety switch for less than $185?
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Unread 03-12-2012, 02:54 PM   #15
inliner6
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found one on ebay -new-mopar- for 130. all is well once again
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