Cvail

I have had a CEL for almost year and when I scanned it I got P0705 and P1899. I have not had any shifting/starting issues so I didn't really make it a priority to check it out. This past Friday night momma was gone and it was raining so I pulled the jeep in the garage and I figured I would go ahead and clean the NSS. Didn't look too bad but I went ahead and cleaned it out, touched all the contacts with emory cloth and applied a light coating of dielectric grease. Put her back together, cleared the codes and drove her for a couple miles and the codes didn't return. Drank a beer and congratulated myself.

5 miles down the road Saturday morning the codes come back. Pull over, clear the codes and drive for about an hour and no codes. Crank her back up in the afternoon and 10 minutes later the codes are back.

So it appears that I can clear the codes, crank it and drive without the codes flagging but if I turn it off and restart the codes will pop up. I'm pretty sure my cleaning job on the NSS was good and I didn't mess anything up.

Does anyone have a test procedure for the NSS? I need to see if there is possibly an issue in my harness or one of the connectors but I'm unsure of the contact logic that I should be looking for in the switch.

Cvail

Meant to add....there are no symptoms present that there is anything wrong with the NSS besides the codes. Only starting in Park or Neutral, back up lights work, torque converter appears to lock/unlock just fine.

CCKen

P0705 is a range sensor (NSS) code, indicating (among others) that there's a Park/Neutral Switch DTC set.

P1899 is the P/N switch DTC.

You can check the NSS P/N switch circuits using an Ohmmeter and checking for resistance between the applicable pins in the NSS connector when the transmission gear selector is positioned to P and N (move ignition key to OFF-first detent from LOCK when making the gear selections). See chart below. This checks the P/N switch contacts in the NSS. The P/N switch cannot be tested from the TCM.

The connector is near the trans dipstick tube (see pic).


Test Chart:





Connector location:

Cvail

Thanks.....I'll check that out this afternoon. Any idea what could cause a P/N fault but still allow the starter to engage. I would think a DTC would be telling the ECU that the selector is not in one of those two position to set the code and therefore wouldn't allow the starter to engage.

CCKen

Don't know for sure, but the switch and wiring to the starter relay control coil must be adequate to pull the starter relay in. The TCM/PCM may be sensitive to a low voltage signal in the P/N circuit (?).


Forgot to mention that the ground for the P/N switch (Transmission Range Sensor) is at G106, on the left inner fender, under wire bundles going to the PCM (see pic). You may want to remove the screws and brighten up the wire ring terminals and the inner fender contacts.



.

CCKen

Do this test, it may be less troublesome.


Using a Digital Ohmmeter set to 200 Ohms.


See PDC starter relay socket layout.


Remove the battery NEG post connector.


Select Park...


Touch pin cavity C10 with the meter + probe and the meter - probe to the disconnected battery NEG cable connector. You should see 5 Ohms or less (less is better) on the meter.


Select Neutral and read the same.

Cvail

So I did the tests about and everything checks out. Running 1.9 - 2.1 Ohms everywhere there is supposed to be continuity and open circuits where they should be open. Not sure where to check now.

Do you think it could be where the NSS ties into the ECM?

Cvail

I just pulled up the ECM schematic. It appears that pin 6 on the black connected is the NSS sense. I measured between the socket and ground and had 2.0 Ohm between there and ground only when the transmission was in P or N.

As of now I have no way of actually telling if the connector is actually making good contact with the pin on the ecu. I do know that it will not turn over with that connector unplugged. I am wondering if the problem is with the TCM.

smarrs

To the OP, did you ever resolve this issue? My 2000 is doing the exact same thing (minus the p1899). Everything tests fine at the connector, no symptoms (reverse lights work, will only start in park or neutral)- the only thing is the damn light!

-Scott

Saudade

The OP was last seen in May 2017. You may not get a reply. Consider starting a fresh thread.