Hi I own a Grand Voyager 2007 2.8 CRD Executive Diesel and it is now off the road due to its strange behaviour. It has gone into its safety limp mode of staying in second gear but whilst i was getting it home the rev counter started racing of its own free will. I took the vehicle to a local garage to access any fault codes but none were showing up, but strangely it showed the car hitting 5mph, whilst it was stationary. After reading many threads on various sites I decided to change the input and output speed sensors. Now when i start the vehicle it sits fine for a few minutes, but then the speedometer rises to 10mph drops back to zero and the rev counter starts moving on its own before going back into limp mode. I have done the key dance and it only comes up with code P1685 which is for the key its self but starts every time.
Any thoughts or help would be greatly appreciated

 

Those symptoms could be caused by excessive ripple current generated by a bad alternator.

You can test for a bad alternator by temporarily removing the field connector from the alternator to see if the symptoms go away. Be aware that with the filed connector disconnected you will be driving on battery power only, your battery will not be charging, so don't leave it disconnected too long.

 

I have disconnected the plug from the alternator and the only change is that the battery light comes on, car still goes into limp mode

 

Did you still have the problem with the speedometer and rev counter?

 

Disconnecting the alternator has made no difference, the rev counter still revs on its own

 

Battery is No1 for eliminating

I would start by pulling the NEG terminal for 16 minutes to clear the BUS, don't do a couple of minutes only .. .. do it for the 1/4 or 1/2 hour, a CAP holds a good amount of reserve to keep the BUS polling and its the BUS that connects the gearbox brain under the OSF arch and the PCM you want to re-set. When you reconnect the NEG you will hear clunks and clangs and all manner of checks being performed, wait till they are finished then start the car and re-set your overhead stuff and clock time etc. I've long argued that that 2.8 should have a battery of [example only] 800CCA/80aH and fylly charged on a smart [example only] .

Depends on the spec of your car but the IOD [Ignition off draw] 'factory-fuse' variously [but you cant see this] controls :

Remote key fob
Radio
Heater blower
Folding mirrors
Central locks
Interior lights when the key is in the ignition
Power seats

According to Chrysler's own workshop manual : Allow twenty minutes for the IOD to stabilize and observe the multi-meter reading. The low-amper- age IOD should not exceed twenty-five milliamperes (0.025 ampere). If the current draw exceeds twenty-five milliamperes, isolate each circuit using the fuse and circuit breaker remove-and-replace process in Step 4. The multi-meter reading will drop to within the acceptable limit when the source of the excessive current draw is disconnected. Repair this circuit as required; whether a wiring short, incorrect switch adjustment, or a component failure is at fault.

A slack [badly fitted] fuel filter [leakback] and for that matter a cracked diesel heater plastic component will cause it not to start, but will not cause 'limp mode'. Your car has a 41TE gearbox. The sweeping needle is an indication of a flat battery.

- did you pull the NEG terminal for 16 minutes to clear the BUS ?
- is your battery now fully charged ?
- the writing in RED mean you are supposed to click on them

With the car in PARK the RPM should be ± [digital meter] 800 ohms, the turbine shaft [input] is measuring the torque converter and at PARK that would be the same[ish]. Now take it out of PARK, put it in drive and the output sensor should rise slowly relative [linear] to the car's speed. Only after that 'live test' should [1st] the input then if necessary (2nd) the output sensor be replaced with calibrated units.

Limp is always a megga problem to chase down. Either it is easy after reading the codes and replacing both sensors or you are in for the long and tortured haul. Most threads involve garages including main stealer's replacing part after part after part then the TCM itself and still it won't work.I wish my post could be more helpful in practical terms and supportive, but I've been there, done that, unlike you it cost me nowt, but the outcome[s] was the same. You clearly are not undercharging you battery otherwise it would not start "every time", but I would still re-set the CANbus [should not affect radio code on an 07] by pulling the NEG for 15-20 minutes. BTW 2nd and reverse are hard wired [get you safe emergency] not CANbus/computer controlled. Best of luck.

GARAGE please NOTE : "Only after" - yes only after testing, put the 'soddin' code reader down and plug the brain in, the torque converter is the same speed as the engine. Do the 'live' test then decide on a menu of probabilities where to put your customers money.

 

Thanks for all of your help guys. I have now changed the alternator, this has now stopped the car revving of its own accord whilst stationary, battery is ok as it starts every time. But it is still in limp mode with all of the gear settings highlighted. The only thing I can think of now, is the ECU shot. i managed to take off the top plug and it did look a little damp in there. Have disconnected the neg of the battery for around 30 mins to try and reset the ECU but has made no difference.

 

Its all Voodoo

What you [personally] can and can't do without you [or a garage] playing 'parts darts' with your money.
If the PRND etc box's are lit [cluster self check sequence] it means the TCM does not know which gear is selected.
The 2nd, Neutral, Park & reverse are human and selected via mechanical linkage. 1st, 3rd & 4th are electronic and selected by the computer [TCM for petrol & EAXT for diesels] via an instruction to the solenoid pack.

Most people can manage an ATF+4 fluid change, never flush just a drain & replace fluid. If you do a replace fluid many many people get lucky and it re-trains [fuzzy logic] itself over a couple of hundred miles on the 41TE. Yes the module under the NSF wing & plastic cover has wiring that goes through a hole in the metal inner wing that is well known to chafe & expose shorting out wires.Your 5/10/15 year old car has possibly (like many of us) never had an essential life giving new gearbox fluid & filter change in its whole life.



Best of luck.

 

Thanks QinteQ I will look into doing a transmission fluid change and see what happens

 

Parts Darts

4+ isn't cheap, ditto the filter . Some go on [see allpar / youtube site] colour / smell / etc I always argue for brain 1st, the thing is having tried everything else and without evidence of it ever being carried out let alone ''stamped' it's still going to be at best a calculated expensive risk my friend friend.

Given I had your problems and risk, I'd go this one extra mile with fluid. Best of luck, caveat emptor.