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[ajd1]

New member, 1st post.
This is an 11/03 Grand Cherokee 2.7 Diesel Auto. Car had been faultless, but a few weeks ago at 62000 miles, noticed that the lights next to the gear selector didn't come on; car reversed ok, but the only forward motion in 'D' was at tick-over; as soon as the accelerator was depressed, the engine just revved.
Main dealer diagnosed shot gearbox (said the fluid was 'sludgy') and wanted £7k fitted. I declined.
Car was taken to autobox specialist who says gearbox is ok, it's an electrical problem; trouble is, he can't find the fault. Says there's a control module somewhere but he can't locate it and is waiting for a comprehensive wiring diagram to turn up.
I should add, if it's any use, that on one occasion, with the autobox guy, the car started and ran ok for a couple of miles, but since then has been as described above.
Any thoughts or ideas gratefully received as I've been car-less for 6 weeks now.

[isle of man]

the nss is faulty........



oh and hello.




peter henry

[ajd1]

nss ??
sorry to be dim!

[ajd1]

ok, goddit; neutral safety switch.
Thank you

[isle of man]

its the switch at the gearstick. don't attempt cleaning it, just replace with new one.




peter henry

[tim_aka_tim]

Neutral Safety Switch, also known as the NPS - Neutral Position Switch.
Seven thousand quid to fix a couple of quid switch? That's impressive even for a Jeep dealer!

[Mike Pavelin]

I don't think it has a NSS as such. Anyone who isn't equipped and experienced in these Jeeps might struggle to diagnose this fault. IIRC, it will have an electronic module built into the gear shift lever assembly, a transmission control module and the powertrain control module. This was the first product to come out of the DaimlerChrysler merger so to add to your misery the transmission is on Mercedes CAN Bus and the powertrain and most of the other controllers on the vehicleis on Chrysler PCI Bus, making diagnostic work very complex if it turns out to be an electronic fault. Many garages will find they won't be able to access all the systems with their scan tools. If the shifter assembly isn't lighting up, I'd look here first and check the wiring.

[wazza]

i second the neutral start switch!!!

mine on the cherrys died compleatly, i had to bridge it out to start an move it but it will only move slowly altho engine revs freely!!!

[Mike Pavelin]

Have done a bit of digging. There is a P/N switch, it's inside the transmission on an electrical control assembly attached to the valve block........

Trans temp sensor - P/N Switch circuit
The TCM will detect the selector lever in park
and neutral positions. The TCM does this by monitoring
the Transmission temperature sensor signal
along with the shifter position signals. The P/N
switch contact is operated by a cam located in the
transmission which, opens a reed contact switch
that is wired in series with the transmission temperature
sensor. When the P/N contact switch is
opened in park and neutral, the TCM senses a high
transmission temperature. Confirming the P/N
switch status. Note: In park or neutral, the TCM
uses engine temperature (to avoid setting a DTC).
The TCM sends a hardwired signal to the PCM/
ECM that will allow the PCM/ECM controlled start
circuit to engage in P or N only. The TCM also sends
a P/N bus message to the PCM/ECM to confirm the
P/N switch status.

However, this shouldn't cause the shifter assembly to fail to light up, so you need to check the shift assembly as well......

Shift Assembly
The Shift Selector is similar to the TRS found on
other DaimlerChrysler products, but is located in
the Shifter Assembly instead of the transmission.
The Shift Selector switches transmit all selector
lever positions to the TCM. Light Emitting Diodes
(LED’s) are used as a light source in order to display
the current selector lever position and provide basic
shifter lighting. The shifter also has a vehicle PCI
bus circuit for communication with the cluster (electronic
PRNDL display). The Reverse light switch is
integrated into the shifter module and controls the
reverse lights through a reverse lamp relay. The
Brake Shift Interlock solenoid and Park lockout
solenoid, are also part of the Shift Selector module
and are controlled by the TCM. The shifter module
also supplies all power to the transmission system.
Note: If there are no LEDS illuminated on the
shifter and the vehicle will not start, the TCM
has a no response check the shifter
assembly power connections

[ajd1]

Thanks guys, this is all excellent info which I hope will lead to a resolution.
Mike, one question .... you mention "... to avoid setting a DTC" ...  DTC ??

My feeling of hopelessness is slowly dissipating ... now, if it was a Boeing I might have a clue !!

[Mike Pavelin]

Diagnostic Trouble Code. Thing is, the transmission will go into shutdown for dozens of reasons. When it does, you get no drive, as you describe. If you turn the engine off and leave it for ten minutes, it will then allow you to limp home if you leave the shifter in the 2 position. To be honest, it might be worthwhile contacting the Jeep dealership and asking exactly what diagnostic work they did, and if there were trouble codes recorded, what they were. The trouble is that the dealerships are not trained to do major repair on auto transmissions, so tend to just condemn thm unless you happen to get a really good keen technician. Do you know if your transmission shop actually have the diagnostic gear required to get into the controller? If there are DTCs recorded it would be a big help if we knew what they were.

[ajd1]

I don't think my chap has the specialist diagnostic gear that you refer to.
I imagine that even a workshop manual would not be much help without the diagnostic equipment.
If memory serves, the main dealer said that no fault codes were shown, but, as you say, they were keen to sell me a new gearbox; begs the question that if I had allowed them to fit a brand new gearbox, chances are it still wouldn't have worked !
My chap is still having no joy. Can you recommend anybody not too far (say, 20 miles or so) from North London who you think might be able to fix it?
I'm just about at the stage where I'll pay whatever it takes to get it sorted.

[daggie]

mike, will a drb111 scan, that motor?

[Mike Pavelin]

Yes, with the right software level.

Adj1, you have a pm.

[ajd1]

Mike, pm sent.

[ajd1]

Thanks to you guys, esp Mike P, for your help.
It was the selector, or at least the electronics beneath.
I will now be having an interesting correspondence with the Main Dealer who wanted £7k to replace a gearbox which wasn't at fault!! They actually chased me pretty aggressively for £155, being the labour (and fluid change) charge for this monumental piece of mis-diagnosis; for a quiet life, I paid up .... now I'll be chasing them.
Thanks again.

[Mike Pavelin]

A main dealer should have been able to diagnose this fault. If you have trouble call Chrysler Jeep Customer services.

[actd]

Hi All,

Does anyone have a DRB III tool or know of a sensible alternative (such as a USB plug and software) - I have a Chrysler Voyager which is showing fault codes and I want to clear these off without paying silly dealer prices.

[Mike Pavelin]

Just disconnect the battery.

[tim_aka_tim]

You have tried disconnecting the battery for an hour?

[actd]

You have tried disconnecting the battery for an hour?

No - does it affect anything else by disconnecting it, such as the radio or any other settings?

[tim_aka_tim]

Make sure you have the radio code before you try.

[Mike Pavelin]

You have tried disconnecting the battery for an hour?

If it's gonna work it'll do it in seconds.

[actd]

You have tried disconnecting the battery for an hour?

If it's gonna work it'll do it in seconds.

OK, thanks all. I'll dig out my radio code and give it a go over the weekend.