C5 V6 ZF 4HP20 Code P0782 2-3 Shift Malfunction

[Jan Calitz]

Thanks, This is the document that I have used to do the gearbox. Space "F" is not shown. They show that they got to a value of about 3 mm and then that one must chose the correct final wear plate (3 of different thickness) Unfortunately the final space is never mentioned. I came right with the other brakes and clutches.
Thanks for your previous message. I did see that the ratios could be different. I have requested information about final drive from ZF. It looks as if the box that I have put in, came from Peugeot 406 2L 16V. Can not get info on this model's use of this gear box. It could be that this ratio could be 3.73 and the original was 3.45 which gives a difference of about 9%. This would activate ESP. I am in process of looking at what Micro is used. I will then have to get code out and change the ratio in EEPROM. Will shop for location of presets. I have many years ago programmed the old 8080 and made my own board to monitor limits on Mill. Kind regards, Jan Calitz

[Mandrake]

Can not get info on this model's use of this gear box. It could be that this ratio could be 3.73 and the original was 3.45 which gives a difference of about 9%. This would activate ESP.

Incorrect final drive ratio won't cause an ESP problem as far as I know, however what it will do is cause an error condition in the gearbox ECU itself, even on cars without ESP.

The ECU measures "input speed" (after the torque converter but before the epicyclic gears) and "output speed" - measured after the final drive gear just before the diff. For each engaged gear it expects a certain ratio between these two speeds, anything outside a relatively narrow margin is interpreted by the ECU as undesirable slip of the main clutches which can result in it going into emergency failsafe mode. It can also affect gear changes because the auto-adaption that tries to optimise clutch engagement overlap will get confused by the mismatched ratios.

We've seen this problem before (I think it was CitroJim) when trying to use a 4HP20 from an XM in a Xantia or vica versa - which have different final drive ratios. Without also changing the ECU it will keep detecting a "fault" because the speed ratios don't match.

I am in process of looking at what Micro is used. I will then have to get code out and change the ratio in EEPROM. Will shop for location of presets. I have many years ago programmed the old 8080 and made my own board to monitor limits on Mill. Kind regards, Jan Calitz

If you're able to make any progress on this I'd certainly be interested to know - I've always wanted to tweak some of the lookup tables in the 4HP20 ECU to improve driveability, (for example neuter the SK1 autoadaptive mode so that it doesn't keep dropping into "old man mode" when driven gently...) but I haven't been able to find any info on even downloading the existing firmware let alone disassembling it.

Your other choices are to find another final drive gear of the correct ratio, or find an ECU that matches the final drive ratio of the gearbox, and at the same time matches the interface in the car. For example some 4HP20's were installed in cars with CAN bus and some without, and are not compatible with each other - there are quite a few different versions of the ECU for a given gearbox, and the lookup tables for gear shifts, torque converter lockup etc are probably different for petrol and diesel as well.

There is a possibility that there is no version of the ECU available which meets the requirements of both the interface with the car and communication with other ECU's and supports the correct final drive ratio.

[Jan Calitz]

Thanks Simon, Will let you know. Regards, Jan Calitz.

[Sloppysod]

Not a ZF 4HP20 but a BVA AM6C1 - Shift Malfunction sorted and I do not believe it!!
My AM6CI gerabox behaves very similar to Jan Calitz's ZF 4HP - not always changing up from 4th, unless I used the gearstick. So after reading this and the linked posts I decided to check the tyres on my car, three road wheels are Michelin Primacy 3's and one is not. I run a tape measure around the circumference, and my spare (a virtually bald Primacy 3) was acually 15 mm smaller than the 'odd' tyre.
I put my spare onto my car and drove it up the road, it behaved exactly as an automatic should, up and down the gearbox without any trouble at all, kick down worked fine, a completely different car - thanks for all the advice, I was actually thinking my gearbox was faulty.

[Jan Calitz]

Hi Simon, How can we get CitrJim connected to this problem of mine? The statement that you make about the mismatch if final drive is wrong makes more sense to me. Remember the display inside car beeps and then reports that transmission is faulty. It happens just after the gear did not move to third gear. It will stay in second until ignition is switched off and car started again. It will change through all gears firs time and second time it faults. Now for the problem: I have Can bus but can not obtain a spare TCU. There are no one in South Africa that has got any. No spare boxes and no final drives. I will have to get somehow the correct TCU numbers before going shopping.
The other part, processor has got no data sheet. I think it has got a complete book covering the micro. It looks as if one will have to get a BDM 100 tool to get to the codes. I will need what code to change to other ratio.
I will open gearbox if removed from car to fix oil leak and open it again when I will take data on final drive gears. So this is where CitoJim will have to come in and help with ratios. Remember that I have not got old gears.
Nice week ahead,
Jan Calitz.

[myglaren]

Jim has rather a lot on his plate just now but rest assured that when he gets time he will have a look into your problem.

[Jan Calitz]

Hi everyone,
Following an update. Gearbox has been removed. Oil leaking at seal "o" ring on oil pump. I have ordered a new one. Hopefully next week? I have established that the final ratios are different. The 4 gear ratios are the same. I have found the "free play" for all brakes, clutches. Look at the URL below and browse through the documents. The original box was code 1019 000 054 and new one is code 1019 000 020. The torque converter is one for V6 C5. I will measure all clutch "free play" according to document. The box will be OK then and can be taken out of the problem line.
https://drive.google.com/open?id=0B6g9L ... DZRQVRaR0k

Simon for you:
I have found that one needs a BDM100 tool to do program actions on ECU and TCU. It also works for other cars. Go look on Youtube for a video on how it works. I am at moment trying to find a disassembler for the program code. One will then be able to figure out what changes to make.
Regards, news will follow.
Jan Calitz.

[Jan Calitz]

Hi Mandrake (Simon),
OK, the gearbox is at last back in. I have ordered Oil and expect it soon. After this we will be able to test the car.
Can you perhaps tell me what to look for on the Lexia once oil level is fine? A list will be appreciated for then I can report back to you and we can start on the fly. I need to start working with a plan.
I bought this car 6 years ago and have had problems with gearbox since then.
I have documented all the things since then and looking back, I realised I will have to take a decision if car needs to be sold as scrap or carry on.
I has been very heavy on the Finances too!
Kind regards,
Jan Calitz.

[Mandrake]

Hi Jan,

I'm not sure where you should start - perhaps try a short test drive and see if the gearbox behaves, if not check for fault codes immediately after the test drive ?

[Jan Calitz]

Hi Simon,
Ok.. we got car going. Gearbox still the same but another problem surfaced: As soon as you move lever from N to D, the gearbox sometimes gives a bang and jerks.
We will investigate it later. First we need to find the shifting problem. We drove the car and took a series of screens on the different modules. They are here:
https://drive.google.com/open?id=0B6g9L ... HNKaEVvaEE

We have noticed that 2 screen shots show gear selected as "2eme". This is during the fault. The display in instrument does not show the gear selected in "D" but does show when in manual selection however gear shown is not always the gear that box is physical in.

We will check the electro regulators to try and see where the bang comes from. Will also test the selector switch.

Kind regards,
Jan Calitz.

[xantia_v6]

The bang is the sudden change into 3rd when the box drops into limp mode (the software does not do any of the things that normally soften changes).

If if is going into limp mode when moving from N to D then you certainly have a faulty selector switch or the wiring to it. There is practically nothing else that the ECU can detect at that time.

[Mandrake]

The bang engaging drive or reverse is indeed probably due to the ECU being in limp mode, which puts the gearbox into emergency hydraulic only mode - its not a sudden change in gear as such, the reason for the bang is that in emergency mode the rail pressure regulator runs at the full 15 bars all the time (since the ECU can't monitor and control slip if proper ECU control of the gearbox has failed) and this causes a large jolt especially engaging reverse. In itself it is not a concern, and is probably not a fault in its own right, it's only the result of limp mode due to another fault. When working normally the rail pressure is regulated much lower when engaging 1st or reverse which gives smoother engagement.

Of the screenshots the one with P1728 sticks out - although the Lexia reports that as "CAN engine torque information", a google search turns up multiple instances of P1728 standing for "Transmission Slip Error", for example:

http://obdii.pro/en/code/P1728

Unfortunately that's exactly what I'd expect to see if the final drive ratio of the box didn't match what the ECU was expecting. If the turbine speed is 3168 RPM and output speed 2112 RPM and it should be for example 2300 RPM in that particular gear then the ECU would interpret this lower output RPM as severe clutch slip and put itself into limp mode almost immediately. As the comparison of input and output speed is constantly used to fine tune the clutch engagement overlap to optimise gear change smoothness, the acceptable error in measured RPM would be fairly small before being interpreted as slip.

P0872 is listed as "2-3 Shift malfunction":

http://www.obd-codes.com/p0782

This could be a genuine problem with the solenoid responsible for shifting from 2nd to 3rd, but its also possible IMHO that the incorrect final drive ratio may fool the ECU into thinking that the change to 3rd was not successful because the output RPM was too low. So I think its likely P1728 is the real cause of your issues and P0782 is a side effect.

Regarding 2eme - I haven't seen that before but I would guess it may be reporting that the gearbox is in emergency mode in 2nd gear ? What ratio does it feel like to drive in that condition - does it feel like you are in 2nd ?

If the box does not feel like it is in the indicated gear then it's almost certainly in emergency/limp mode.

If replacing the final drive gears in the gearbox to get the correct ratio isn't possible, I think you're back to replacing/reprogramming the ECU to accept the fitted final drive ratio as your only solution I'm afraid.

[Jan Calitz]

Hi Simon, Thanks a lot for your time and effort. Exactly what I was scared of in the onset. I did count the intermediate gear tooth (the one on which the output speed sensor sits counting) and it has got 71 teeth. According to the data sheets that I got from ZF shows a count of 58 (I think, will make sure!) for the correct ZF gearbox for the C5.
You do not know what the codes for the Xenia V6 box must be? I could try to substitute the TCM?
Kind regards,
Jan Calitz.

[Mandrake]

Hi Jan,

If by TCM you mean the Gearbox ECU, then no, you will not be able to use the TCM from a Xantia in your C5 - the Xantia ECU is not CAN bus compatible nor is it ABS/ESP aware. It would not be able to communicate with the Engine ECU or ABS/ESP ECU. (It also doesn't support flappy paddle gear change controls)

The Engine ECU, ABS/ESP ECU and Gearbox ECU are all designed to talk to each other in a symbiotic relationship so you can not mix and match older models of ECU even if it was the right ECU (final drive ratio) to match the gearbox mechanicals.

Sorry!

[Jan Calitz]

Hi Simon, sorry my Internet was down friday. We took the car for a proper run. Went further and took some Videos of screen showing some test points. I did not include it here but as soon as my son wakes up saturday. I ran the one video and took freeze frames. I will share them with you. I do not know if you will be interested in the video's? Can you please suggest which points to put on Video? Don't stop at the 6 allowed. I will filter them out as we go along and take ones that I can say are correct and add some of your other suggestions in. have found the tooth count for the two different boxes from ZF in South Africa. Wonderful response!! Ok the broken Citroen gearbox has got 59 teeth, the peugeot g-box has got 58 teeth. That gives a fault of close to 2%. On some of the screen shots the output speed seems to be 20 RPM different, but then on others the RPM is very close.
Something I have noticed is that the electrovalves regulate between +700 and +100 mA but then drop to 45mA! Strange, I can not find this phenomenon in all the documents. Can you help here??? We drove the car very light but had to use tiptronic shift.
The P0** codes are vehicle or manufactures own specified code. I will investigate the code on Saturday. I have got a comprehensive DTC codes for each car up to 2011 This is a book that is about 5 inches thick. Can not go and scratch because granddaughter is sleeping in same room.
Kind regards,
Jan Calitz.