L322 ZF8HP70 gearbox problem

Graculus said:

Don't do that! The only time that should be done is if a software change requires it or solenoids have been replaced, doing so on a 'box that has had no work done can lead to some pretty bad shifts, some 'boxes never achieve their previously 'acceptable but could be better' shift behaviour.

Click to expand...

kermit_rr said:

I didn't see a live data selection called output speed sensor but saw a few others.
Transmission output shaft speed was interesting, it was at zero apart from a spike when starting and a spike when stopping.
There was transfer box motion sensor voltage which went from low to high, the switch happened before i came to a stop

Click to expand...

A new feature of the 8 speed transmission is decoupling of the transmission
when the vehicle is at a standstill. Normally the transmission remains in gear
with the torque converter slipping and the vehicle is prevented from moving
by applying the brake. The new system disengages one of the transmission
clutches and only a minimum rotating load remains

Click to expand...

Speed Sensors

The turbine speed sensor and the output shaft speed sensor are Hall effect
type sensors located in the Mechatronic valve block and are not serviceable
items. The TCM monitors the signals from each sensor to determine the
input (turbine) speed and the output shaft speed.

The turbine speed is monitored by the TCM to calculate the slip of the


torque converter clutch and internal clutch slip. This signal allows the TCM
to accurately control the slip timing during shifts and adjust clutch
application or release pressure for overlap shift control.

The output shaft speed is monitored by theTCM and compared to engine
speed signals received on the CAN bus from the ECM. Using a comparison
of the two signals the TCM calculates the transmission slip ratio for
plausibility and maintains adaptive pressure control.

Click to expand...

Graculus said:

This sounds like it may be relevant to your issue:-


And

So the output speed sensor monitors and reports rpm, it's not an 'on-off' sensor, which yours seems to be behaving as. Unfortunately it's not a serviceable item from LR - but may be at a ZF service centre.
You may wish to have a proper diagnosis carried out rather than a virtual one if it involves spending what little cash the incumbent Gov't. leaves you with.

Click to expand...

Graculus said:

You can change the Mech, I've done quite a few on various ZF 'boxes - even more on M-B & VWG transmissions... If the sensor is defective and it is replaceable seperately, then a ZF centre will be able to do it, your transmission specialist may be able to do it if ZF sell it as a spare component to third parties. I would advise getting a proper, physical diagnosis carried out to confirm this 'virtual diagnosis' before committing to any repair though.

Click to expand...

Graculus said:

You can change the Mech, I've done quite a few on various ZF 'boxes - even more on M-B & VWG transmissions...

Click to expand...

Mark Piercy said:

The box in the Chrysler/merc 300d? yep seen that one.

Click to expand...

Graculus said:

No, much more recent vehicles than that! many still in manufacturers warranty....
When I was at VW, there was at least one vehicle a day in for a Mech. replacement, where I am now, we average two a month, again, not particularly old vehicles.

Click to expand...

kermit_rr said:

i wonder if this lack of data is why the cruise control is rubbish?

Click to expand...

Mark Piercy said:

That's plausible mate

Click to expand...

marjon said:

Founds this and found it quite interesting.

The Definitive Guide To The ZF 8-Speed Transmission (8HP45) - Specs, Common Problems, Diagnostics, & Maintenance

ZF Friedrichshafen was formed just after the turn of the 20th century in Germany. Initially, ZF was dedicated to designing parts for Zeppelins, but the quickly growing automobile industry soon became their main focus. By 1934, Zahnradfabrik Friedrichshafen had built their first fully...

www.fcpeuro.com

Although the history of use in Range Rover seems wrong.

But anyway worth a look, some interesting points made about the electrical connector.

J

Click to expand...

kermit_rr said:

The rubber sleeve thingy was replaced with three oil change, no dash lights or codes so maybe a scarlet sardine

Click to expand...

marjon said:

But.. Was the plug clean of oil? Maybe a pink salmon but
As there's so much going on in the box and you are having issues with signals coming out, worth a look/thought .

Did like that "neutral" bolt though, cant remember seeing it when I did my front prop, as it kept dropping into park and it was a PITA. (need to look back on pics).

J

Click to expand...

kermit_rr said:

isnt the neutral thingy what you operate when you pull on the red strap under the cup holders?

Click to expand...

marjon said:

Yes I thought it could be done from under the cup holder along with the EPB release.
Need to check, have to remember he was talking BMW so could well be different for JLR.

J

Click to expand...