Gearbox Problem-Sort of Merc

[reflexboy]

OK, not exactly a Mercedes car, but a Mercedes engine and gearbox in a 2.7 CRD Grand Cherokee(hope that's ok Moderators, if not feel free to delete). I believe this is the same engine and gearbox as in the ML270 CDi. Fault is: If the car hasn't been driven for a day or two a solid yellow warning lamp appears on the dash. This has been put on the diagnostics and only a general code pointing towards the transmission comes up. When the light is on the car changes through all five gears fine, although a little rougher than normal. After about 15mins of driving the light goes out and the gear changes are 100% perfect. This started a few weeks ago and has got worse to the extent that occasionally when the light is on (say one in five times) the gearbox won't go further than 2nd gear. If I turn the engine off and re-start it then it will change through all the gears ok, and will then go on to get smoother after 15mins of driving once the light has gone out. It has been with a Chrysler dealer for the day and they have basically got nowhere as the lamp wasn't on. They will try again in the morning. On my last visit they told me they would print off a schematic from Chrysler to work through testing resistances and voltages as various points. Obviously we are paying for this labour and are keen to get the fault repaired as soon as feasable. It seems to be a heat related fault possibly. Also bear in mind I believe this is an electronic gearbox with solenoids and sensors!! Do any of the forum members have any idea what the fault may be, either through personal experience ( ie: same engine and box as ML270) or because you guys seems to be very knowledgeable? Lots of thanks in advance

 

[Buggerlugs]

Speak to the dealer and get the fault codes that were stored, post em here and then I can help, I really wouldn't even start to speculate without this.

 

[reflexboy]

Hi-The code that i read off the dash display and the code that the dealer read on his diagnostics was "P-0700" which if you go here: http://www.wjjeeps.com/faultcodes.htm
and scroll quite far down simply says:

P0700 (M)
Check Transmission DTC's
This code indicates that the EATX (Transmission controller) has an active fault and has illuminated the MIL via a BUS message. The specific fault must be acquired from the EATX via a DRBIII tool. (Input or Output Speed Sensor failures often cause this code and are a common failure part on WJ Grand Cherokees).

But bear in mind that is a US website and over there they only have the 4 litre and 4.7 litre V8 of this era, with Chrysler transmission (2002), where as this is a Merc transmission.

 

[rpe2]

Assuming it is a 722.6 gearbox, then it is probably the conductor board at fault. From memory circa £200 for the part + fitting.

Richard

 

[reflexboy]

Hi Richard-Thanks for your reply. What is a conductor board? Do you mean the gearbox controller/ECU?

 

[Buggerlugs]

Ok, P0700 is a generic engine management DTC and basically says that the engine controller has received a DTC flag from the Transmission module, so now, we need the specific transmission module DTC's.

If the car is at the OEM (Chrysler/Jeep) dealer this shouldn't be a problem, if it's not, then they need to be equipped with a suitable diagnostic tool, I can tell you that the MB Star doesn't work, so it'll need a Chrysler DRBIII or similar. Also some EOBD scantools will work, but only the ones that let you select a specific compliant powertrain module at the opening screen.

 

[reflexboy]

Thanks Buggerlugs-I didn't manage to speak to the Chrysler dealer where the car is at the moment today and the donuts rang the wrong number when they tried to contact me. D'oh. They did however leave a message saying they would like to speak to me about the price of changing the ATF and filter and 'flashing' the gearbox ECU's software. Would this sound about right to you considering the problem I have described above?

PS-I will ask them about the specific DTCs when I speak to them tomorrow.

 

[rpe2]

Hi Richard-Thanks for your reply. What is a conductor board? Do you mean the gearbox controller/ECU?

I'm refering to the circuit board with the speed sensors built in which resides within the gearbox above the valve body.

Best to get a definitave fault code read-out before commencing any work.

Richard

 

[Buggerlugs]

Thanks Buggerlugs-I didn't manage to speak to the Chrysler dealer where the car is at the moment today and the donuts rang the wrong number when they tried to contact me. D'oh. They did however leave a message saying they would like to speak to me about the price of changing the ATF and filter and 'flashing' the gearbox ECU's software. Would this sound about right to you considering the problem I have described above?

PS-I will ask them about the specific DTCs when I speak to them tomorrow.

Now that depends on whether they're gonna charge you for the ATF/filter change and reflash even if that doesn't fix it? You need to clarify this, we always state "no fix, no fee!" But I doubt somehow they're gonna be quite so compliant. My experience tells me that the TCM reflash is the only thing likely to make a difference, but to give you a proper informed opinion I still need the trans DTC's.

 

[reflexboy]

Buggerlugs-I see exactly where you are coming from and couldn't agree with you more. I did mention all you said about specific DTCs to the service department. He was absolutely adamnet that they use a Chrysler specific DRB2 tool and as that is specific to Chrysler they will get no more info from a DRB3. I did tell him I thought the DRB2 only brought up the P-0700 code and the DRB3 would give an exact diagnosis of the faulty component. He babled on about solenoid valve pressure and basically told me that the technician working on the vehicle said an ATF and filter change and a software 'flash' would cure the problem, which to me basically says they will fix it for the price they quoted me today. No filter or torque converter gasket in stock today so it looks like I will be collecting friday evening. Watch this space!!

PS-I wish you lived nearer as you sound like you know what you are talking about and inspire far more confidence than the stealer.

 

[Buggerlugs]

DRB2 or 3, doesn't matter, both can interrogate the TCM. I suppose to sum up, you can't get P0700 alone ie; without another DTC to trigger it. Wish I could be stood alongside when the spiel is flowing........Anyroad, I'll keep em' crossed for you.

How much for the fluid change and reflash by the way?

 

[panason1c]

My thoughts are that this could be a 'maf' problem.......a faulty maf doesnt always flag a diagnostics code.

 

[reflexboy]

DRB2 or 3, doesn't matter, both can interrogate the TCM. I suppose to sum up, you can't get P0700 alone ie; without another DTC to trigger it. Wish I could be stood alongside when the spiel is flowing........Anyroad, I'll keep em' crossed for you.

How much for the fluid change and reflash by the way?

£316!!! I suppose this maybe for the labour as well. Just found out after they were unable to do the work yesterday because they needed to order the filter at 8am yesterday that today it still isn't ready tonight either as apparently not one Chrysler dealer in the country has a filter and they have ordered it from Germany and are expecting it Tues/Wed. My my, they are doing well

 

[reflexboy]

Well, I recieved a call yesterday and the g/box filter is in. Just dropped the jeep off this morning and will hopefully collect this afternoon. Sadly, I won't really know for sure if they have cured the problem as it is intermittant and tends to happen when it is really cold. Of course, the last few days have been a bit warmer and sod's law was that the MIL wasn't even illuminated this morning!!

 

[grober]

here are list of fault codes which as has been said probably require the use of a DRBIII TOOL scroll down to FAULT P0700M on the list. http://wjjeeps.com/faultcodes.htm They seem to think failure of the input or output speed sensors is a very common fault on these gearboxes. http://wjjeeps.com/speed_sensors.htm not sure if this applies to the CRD GEARBOX or not

 

[reflexboy]

Thanks Grober. I read that, but the website is from the US, so I'm presuming this is refering to the 4.0L and 4.7L engines that were available at that era in the US. Hopefully by tonight it will all be sorted.

 

[reflexboy]

Found this on the web, which does in fact tie in with the dealer's diagnosis:

http://wjjeeps.com/tsb/tsb_wg_2100908.pdf

 

[Buggerlugs]

P0657 in the TCM is the trigger in that case for the P0700 in the ECM, there are around 30 other TCM trouble codes which will trigger the exact same P0700 in the ECM, the P0700 is basically an indicator that the TCM has transmitted a MIL (Malfunction indicator lamp) illiumination request and the MIL is controlled by the ECM, so you see what I mean about getting the TCM codes?

 

[reflexboy]

I understand it now Buggerlugs. Maybe the dealer was reluctant to give me the TCM code. Well, I got the Jeep back and so far so good. The real test will be when the car has not been driven for a couple of days and the temperature falls again. Once again, many thanks for your help and expertise and I'm only sorry I don't live nearer to you as you seem like the man to approach with gearbox troubles. Best of luck to you and thanks.