Was hoping someone could help me out ...I have a P1720 error and I also have a C1175...

Anyone been through this one before...P1720 is loss of output speed and wheel speed information

Under P1720 it states it will also throw a C1175 error ...so I think the root of the issue is the P1720 error

The C1175 is the left rear wheel sensor which I've swapped out so it doesn't appear to be an issue

 

It's almost never the sensor, the wires in the cable can break. But could P1720 be a transmission speed output fault?

 

P1720 is loss of output speed and wheel speed information

How often is it actually the sensor in the transmission as opposed to wiring to the transmission...so should I be looking ABS to TCM connection and tcm connection to transmission

 

There have been a couple of reports of the transmission plug needing cleaning. To unplug, disconnect neg batt cable first. There is a locking ring on the plug that has to be rotated. Push the tab on the ring with a screwdriver if I recall correctly.

You can also locate the yellow and green twisted wire pair for the CAN circuit and check the resistance-60 ohms.

There is a thread open now on the forum that you may want to check.

https://www.jaguarforums.com/forum/x...roblem-175264/

 

Doesn't sound like a CAN fault.

The C1175 is the clue I think.

 

I am planning to check the electrical connector on the transmission and then start testing resistance at the pins...see attached pic for how the c1175 is tripped...it looks like this doesn't have anything to do with the wheel speed sensor, which I've checked and swapped .::

Also this is intermittent with little rhyme or reason...I'll be driving the stability/traction error message with a lit ABS light...even then very occasionally he gear box fault comes on and the tranny stays in gear....the gear box warning does not happen everytime I get the ABS light

After an ignition cycle the error goes away and abs light disappears after reaching 10MPH

Any other thoughts welcome
2001 XJR

 

Dubious connection/wiring / failing bearing / etc - any of the usual failures for cars of its age. You know from C code roughly where to look.

 

 

I just checked the electrical connector that goes into the tranny and cleaned it with contact cleaner

The whole plug that goes into the transmission was pretty oily so I am wondering if this is my issue ...oily connector that goes into the transmission

 

pdog2000, We'll be anxious to hear how it goes!

RJ237, Good call!

Cheers,

Don

 

Thanks Don. It's too soon to pat myself on the back, but I'm hoping the fix is this simple. Not a common problem with the ZF box, but I've read about it being the cause of similar codes with the Mercedes unit in the R models.

 

So far so good...no issues after about 50 miles...let's see what happens in the next few days

 

ok it worked...well at least i hope it did after 600 miles and about 3 dozen car rides...ever since i cleaned the connector, pics above, i haven'd had the issue again...

 

so it did not work...i am bummed

the error came back just as i passed 1000 miles from when i cleaned the connector that goes into the transmission...i did drill further into the IDS troubleshooting screens which seemed to firm up what some of you were saying related to a CAN issue...

also this time around when i saw the ABS light come on with the no trac no asc message the check engine light came on for a few minutes...

so for now i am guessing either the plug into the transmission, the tcm module, the abs module or some cable in between...this really sucks though, so hard to find the problem....any tips would be greatly appreciated...

oh one other thing...the heat shield that attaches to the transmission to protect the transmission cable on my car is missing so could the heat be compromising one of the wires in the transmission cable? i guess i need to also check if any CAN messages even go between the transmission and the TCM or if i have narrowed it down to be a TCM to ABS issue?

please help

 

still got the issue, i tried cleaning the plug again...this one is wearing me down...i am wondering if it actually is the speed sensor instead the gearbox?

 

Hi,

was the connector oily again?
The MB boxes are known to leak at the connector when ageing. There's an upgraded version of the connector sleeve with thicker o-rings available. Easy to fit and cheap. If you google "connector leak w5a580 or 722.6" you'll get quite a bunch of results. Worst case scenario is that the leaking ATF will draw into the cables and being soaked into the TCM (via capillary forces) which causes multiple confusing DTCs. That's the reason why some Benz drivers considered installing an oil barrier before the TCM. I did too, but didn't install it yet. Dependent on which of the 2 o-rings fail, you wouldn't even notice any ATF dripping on the floor, as the outer o-ring might be still intact. But with the second o-ring failing, the ATF will enter the connector and therefore the wiring loom, without being noticed by you since the outer o-ring prevents the ATF from dripping onto the garage floor.
So if your connector had been oily then I'd recommend changing the connector sleeve with the upgraded version and see if the codes disappear. If not, I'd consider replacing the wiring loom to the TCM.
Best regards, Alexander

 

Thanks Alexander...do you think there is any chance it could be my abs module? The connector wasn't oily the next time around...

 

Hi pdog2000,

If it were up to me I'd go for checking the wiring looms and the TCM. I doesn't take much time and effort to remove the covers in the engine compartment for checking if there's oil at the TCM connector and/or in the TCM. Take a closer look here and for some impressions of ATF oil drawn into the TCM.
I might be wrong on this, but it might be possible datalogging the sensor signals of the wheel speed sensors. That way you can compare the signals of all four signals and see if you can catch any anomalies with the rear wheel speed sensors. Or, if you want to do it the easy and fast way just replace the wiring looms with used ones from the breakers yard or off eB*y.
Keep us updated on this!

PS: No, I don't think it's ABS module related. For 99.9% all ABS module problems are related to weak solder points of the ABS pump (causing C1095). Otherwise there are not much more of known weak points with these modules. As already mentioned before, the wheel speed sensors are almost bulletproof too - but the harnesses aren't.

 

Thanks all..I am heading down the route of checking the gearbox wiring harness...LNF3030CC

Haven't found one on eBay yet...will let you know

 

after the many months of trying to fix it...I still have the issue...let me know some thoughts
- I've wrapped the wire going from my Gearbox to TCM with flexible heat shield fabric as the main heat shield that should have been attached to the gearbox was gone and I thought the wire overheating could affect its movement of voltage or resistance
- I've replaced the plug on the gearbox that the cable plugs into as when I disconnected the cable it did have some fluid in there on the pins, so I replaced it as I guessed one of the rubber seals was bad...
- when my mechanic went to change the plug the screw was stripped and the connector was slightly melted to the conductor plate...so I had the whole conductor plate changed, which includes the hall effect sensor which was one of the items I thought could be causing this issue so that has been ruled out as well
- all my wheel speed sensors have also been charged due to an unrelated error from the front right sensor, which was a bad cable that I did replace...


so what is left is
- ABS module change
- cable from gearbox to the TCM...I did order what I thought was the right cable, but I was wrong...still trying to figure out where I can get this ordered
- maybe the ABS cable changed out?


any other things I need to be looking...