reverse gear problem

[stevenstewart42]

Hi
Got a strange one here. When I select reverse I get the selector light indicating reverse, rear parking sensor make a noise. When I give it some gas there is no drive. After a few minutes the trans fail safe warning message come up and now when I select reverse and give it some gas I now have movement.
I have given it an oil and filter change but still the same.
I also have the brake, abs, and traction control lights on.
Anyone have any suggestions as I am a bit stumped at the moment.

[lincolnshibuya]

get it scanned for codes, use a scanner that can read BMW codes.. sometimes the freebie scan in the parts store is not enough depending on the type of scanner they have.


post the codes here..


https://www.facebook.com/diybmwx5/

[stevenstewart42]

OK will get it scanned and get the codes posted tomorrow.

[upallnight]

Originally Posted by stevenstewart42

Hi
Got a strange one here. When I select reverse I get the selector light indicating reverse, rear parking sensor make a noise. When I give it some gas there is no drive. After a few minutes the trans fail safe warning message come up and now when I select reverse and give it some gas I now have movement.
I have given it an oil and filter change but still the same.
I also have the brake, abs, and traction control lights on.
Anyone have any suggestions as I am a bit stumped at the moment.

You're stump at the moment, how do you think we feel? There are many variations of X5. Petrol, Diesel, I6, and the numerous V8's engines that were installed into the X5. No where did you mention which X5 you have. Different X's used different gearboxes. ZF box or the GM box? Too little info to tell you what is wrong with your car.

[stevenstewart42]

Hi
sorry for the lack of information regarding the vehicle.
It is a 2001, 4.4 V8 with the ZF gearbox.
Part number for the gearbox 24001423950 (Realoem)
Hope this helps.

[RRPhil]

You have a ZF 5HP24 transmission, ZF model number 1058 000 029.

Assuming for a moment that you don’t have an electronic/electrical issue, but a mechanical/hydraulic one instead:

Reverse requires two clutches to be engaged, C & F.

In August 2001 ZF carried out modification number 8740B where they changed the material of the F brake piston due to wear issues and subsequent pressure leakage.



The piston part number changed from 0501 208 317 to 0501 212 967.





As yours is a 2001 model it may, or may not, have the upgraded piston fitted. If you can supply me with the serial number off the green ID plate rivetted to the left-hand side of the maincase, I can tell you.




Another possibility is leakage in the C clutch circuit. To ensure smooth engagement of reverse from neutral when stationary, the C clutch has an accumulator or damper circuit which allows the clutch to fill quickly but then slows the application of pressure (and therefore torque capacity) using a system of one-way orifice valves, to prevent harsh engagement.



The underside of the damper/accumulator is fed with modulated system pressure. At zero throttle the modulation pressure will be low and the accumulator piston can move freely, allowing the system to provide smooth engagement. If the transmission is in failsafe then the modulation pressure is at its maximum and it prevents the damper from moving, thereby bypassing the orifice valves and allowing the clutch to engage at full pressure. If there is hydraulic leakage in the C clutch circuit the clutch will not therefore engage when the accumulator circuit is active, but will engage in failsafe mode. This can also be demonstrated by temporarily removing the connector from the 16-pin plug on the back of the transmission.



Anyway, this is all just speculation. You first need to eliminate the possibility of it being an electronic/electrical fault, which would be much cheaper to fix!

Phil

[stevenstewart42]

Thanks Phil.
You obviously no what you are talking about. That was a really interesting and informative. The serial number on my gearbox is 0360305.
I will try disconnecting the electrical connection and see if that replicates the fault. I have also just purchased diagnostic software INPA and ISTA and will try these and see what sort of information I can pull from the car to aid with fault diagnosis.
What electrical fault would cause these symptoms and if it is a fault within the gearbox itself is it more economic to replace the gearbox or repair. I only ask as I have been offered a low mileage box complete with torque converter and transfer box for a very reasonable price.

[RRPhil]

Your transmission came off the production line at Saarbrücken on 30th November 2000 so it is fitted with the old F-brake piston design (unless, of course, your transmission has since been rebuilt and updated).

We really need the fault codes from the diagnostics test to be able to help determine if you have an electrical or electronic fault.

Temporarily removing the 16-pin connector will force the transmission into failsafe mode and the transmission will select 4th gear when you engage Drive, and Reverse should operate as normal. Because the pressure isn’t modulated in failsafe mode it will engage with a ‘clunk’. If Reverse works perfectly without the plug connected but then doesn’t work once the plug is reconnected, then my opinion would be that you have an internal clutch leak and the transmission will require a rebuild. This isn’t cheap (for example, I charge £1650 incl. VAT) so it is worth considering a replacement transmission, providing you know its history. Clearly, though, this isn’t without risk.

I assume that the transmission you’ve been offered is from a 4.4 V8 M62 E53? The reason I ask is that there are 24 variants of the 5HP24 transmission, and only one of them – the ‘029’ model – will fit your X5. Actually, I lied. The ‘034’ model from the 4.6iS would also fit in your car but it has extra clutch plates, a different torque converter, and revised hydraulics to suit the higher torque engine so it isn’t really suitable.

Out of the 335,000 5HP24s that ZF manufactured for BMW just over 85,000 of them were ‘029’ models for the 4.4 E53, so they’re fairly easy to come across (only 11,000 were ‘034’ models for the 4.6iS).

Phil

[upallnight]

The good news is you and RRPHIL are on the same side of the pond.
You have a ZF specialist that can repair your old box. I would trust a rebuild job by RRPHIL before buying and installing a used box with no history.

[Rokolya87]

My reverse was engaging with a clunk for some time. I thought the fluid change might help and lost the reverse gear pretty much entirely right after. It engages when cold, but disappears after about 5min of driving/idling.

Tranny number 0356808
5HP-24, 000029 model

I'll try to pull the 16 pin connector, see if the reverse comes back in fail safe mode tomorrow