Hey Lads,

In my previous thread on this topic, I was having a "bump" issue when the car rolled to a slow stop and dropped back into 1st gear. It was very annoying and a little concerning as I had just bought the car.

Did a transmission service with filter and Mercon SP transmission fluid, ran the car for about 100 miles and the bump had dropped about 75%. Last night I drained the fluid again and replaced with new and now the bump is down to about 10% of what it used to be and probably would go unnoticed by anyone else.

So late last night after I changed the transmission fluid and also put in a new bath of Royal Purple XPR racing oil, I decided to take the car for a road test. Things were going nicely and I decided to do a kickdown on the highway. As soon as the car kicked down, I got a "Transmission Fault" warning on the dash and the transmission went into a single gear "limp home mode".

So I took it to my friends shop this morning as he has a really good scanner and he told me what the stored codes were. There were a couple of irrelevant ones but two interesting ones.

P0735 - Gear 5 incorrect ratio
Obviously the code that threw the warning. Makes sense as that was the gear I dropped into when the car went into limp home mode.

P1571 - Brake Switch Malfunction
This is the interesting one. My friend owns a shop that specializes in imports and he told me that the brake switch is tied into multiple functions on this car. He said it is tied into the transmission as well and that if that switch is bad, it can have an impact on the way the tranny works.

Just wondering if anyone has experienced this before?
After I shut the car off last night and restarted it, the transmission shifted fine again but I haven't gotten into any kickdowns with it since.

Here are the other codes that were stored:

P1260 - Security Input (radio code?) I haven't reset it yet
P1582 - Flight Recorder Data Is Stored (This thing flies?)

P0430 - Catalyst Efficiency Below Threshold Bank 2
I have no OBDII codes stored so what is this one telling me?

Off to do some research but would appreciate any experience or input.

Bernie

 

I think I have heard that the brake switch can cause the trans issue.

 

For best assistance, post ALL the codes. Anything about wheel speed input?

 

Those were all the codes.

The first two were the important ones.
The rest were on the computer

Bernie

 

You can do a search to convince yourself, but the brake switch is a common problem. I have replaced mine, as have many others. Some parts store refer to it as a cruise control switch. It is a an easy job in the sense that all you have to do is replace the switch (nothing else needs to come off), but it is a pain to access as it is behind and above the brake pedal. There are many write-ups about this (some involving foul language), boiling down to a debate between removing the bracket with the switch on it, or leaving the bracket in place, and swapping out just the switch body.

Have you seen any "Check rear bulbs -- cruise control not available" message before? If so, that is another hint that the switch is bad.

Best of luck, keep us posted.

 

Here are some DTC guides for your car.

The P1260 means that the KEY was NOT recognized sometime when you went to start the engine.

P1582 is the DTC for EDR (Engine Data Recorder) and you cannot clear it with a generic scan tool. You must go to setup and configuration for modules, and then you can read/delete the EDR info.

The catalyst monitor you already know as well as the other common DTCs.

bob

 

Pushing this thread back up to the top because I have a bit more news and I am also getting around to working on the car again soon.

So I haven't driven the car very much as it has the transmission issues still and I also get a rattle from the VVT system (i think?) every time I start the car after leaving it for a while. I figured it was best to limit using it until I got my head wrapped around a few things.

So not long after I had made this original post, I did get warnings of the cruise control being unavailable and a light warning. Guess that seals the deal for replacing the brake switch.

The transmission issues remain and now I have learned even more. I was mortified on a couple of occasions that when the tranny kicked down, I got a howl coming from the unit. I thought that was it, all over but now I have read about the common "squawk" problem with these transmissions so I don't feel so worried.

To summarize where the shifting is right now:
1-2 has a feel of some hesitation in it. Not crisp.
2-3- no issues
3-4- no issues
4-5 - feels like it clunks a bit.
5-6 - no issues

Haven't experienced any issues when it downshifts other than it still has a bit of a bump going into first which doesn't happen until the car is nearly dead stopped. Seems really late to shift to first.

So there are a couple of things I want to check.
First I did the fluid change twice and did it myself. The first time I was rock solid on the procedure, the second time I fumbled more so I want to make certain that the fluid level is dead on. Probably will take it to my shop and have them do it on the lift - so much easier.

So now I know about the magic additive that was put into a TSB from Jaguar to address the squawk but it says it should only ever be done once. I certainly didn't see a label on the old pan stating that it had been done but I bought the car at 120k so who knows for sure? I am hoping the dealership would be able to confirm it in their records if it had been. If not, maybe I should do that as well.

The big question mark I have is about the adaptive reset procedure. Have read dozens of posts on the subject but my question remains. We have the simple - disconnect the battery and cross the leads to bleed out any intel the computers have stored. It sounds like this puts you back to a factory fresh setup from where the car can relearn again. The fluid in my car was old and might have been the original fluid so I am certain that the module has adapted itself far away from the proper settings. So my question is - Is this the same reset procedure that the dealer will do with their computer system or is that something different.

I would also want to confirm that I have the latest firmware as well but the adaptive reset procedure has me confused. Are we talking the same thing? If so, why doesn't the dealership do it that way instead of hooking it up to a computer to reset the system? Oh wait - expensive computer = lots of money charged to do the same thing....lol

At least that is what I am hoping

Thoughts?

 

My 05 has a sticker on the drivers door jamb saying the computer has been updated, does yours? Regarding codes, replace the brake light switch and report back. In my case, having never done a Jag. switch, I removed it from the bracket and replaced just the switch. Was necessary to bend the bracket away from the pedal then bend it back with the pedal depressed, engine running.

 

CLEAR ADAPTATIONS is a procedure that is done with a diagnostic computer.
When the procedure is chosen from the menu, you will sometimes get a screen prompt that the ECM must also be configured/updated. Sometimes the TCM will just allow CLEAR ADAPTATIONS. It will depend on the software level installed.

You click CONTINUE.

A hard reset will do NOTHING to clear TCM adaptations.

The fluid additive is NLA. The newer fluid formulation from ZF already contains the chemicals needed for the 'squawk' fault.

bob

 

Thanks,

Yea I have read some of the nightmares guys have had working on these. I will check the doorjamb and see if there is any indication that it had been done before.

Thanks!

 

Thanks Bob,

You know I have read post after post about people saying the putting the positive / negative battery leads together were getting some major improvements on the shifting in the car. I had read before that it doesn't reset the adaptive in the TCM so what are we dealing with here. Is it doing something else or is it merely a placebo?

Going to try it anyway as it is on the cheap side with regards to repairs...lol.
So the dealer will have to reset the TCM and it should fly up a firmware upgrade request. Ok, then that's my next move.

I swapped my transmission fluid over to the Mercon stuff so I guess what I have forfeited the element of the ZF fluid in the process?

Bernie

 

The DEALER does not have to clear adaptations. Anyone with the proper diagnostic equipment can perform the configuration. I have BOTH WDS and IDS so it can be done with those and I think AutoLogic and maybe AutoEnginuity or others if they have the software update installed???

The TCM might already have the latest software but if the gearbox has had low fluid level or some other malfunction it will 'learn/adapt' bad habits. The CLEAR ADAPTATIONS simply puts the TCM into a 'blank-slate' state to relearn shift patterns. After the TCM adaptations have been cleared there is a procedure to follow to allow the TCM to adapt properly as per TSB S307-17
"Carry out the adaption drive cycle road test:
• Drive the vehicle for ten miles in an urban environment to provoke the transmission
to carry out upshifts and downshifts.
• Use light throttle only and do not exceed 2500 rpm.
• At one point in the drive cycle, when the traffic conditions allow, accelerate gently to
60 mph (95 km/h) then allow the vehicle to coast down to 25 mph (40 km/h).
Note: This process must be carried out in normal mode (not sports
mode). The transmission fluid temperature must be above 60°C
(140°F) (Having the vehicle at normal operating temperature will
ensure transmission fluid temperature is above 60°C (140°F).

Note: The customer must be advised to use normal mode (not sports
mode) for 200 miles (321 km) and to try to avoid full throttle/kick down
over this period."

As to your other question....
Mercon may or may not have some additive that will help with the shifting???

I use the proper ZF fluid so I don't know about other kinds.

bob

 

Bernie,
I once had the "Gear 5 Incorrect Ratio" warning and a slew of others come on all at the same time. And like you, I had the car go into 4 gear only limp home mode, no cruise control, etc.

As ridiculous as this sounds, the cause was a loose battery connection in the trunk. I guess the last mechanic just wiggled the connector onto the terminal for testing and forgot to tighten it. I tightened it up and the problem(s) never returned. That was two and half years ago; approx. 50K miles.

 

Thanks Bob,

With your experience I was most intrigued to hear a response about this battery lead crossing technique that supposedly does the same thing. There was one thread that had post after post about this making an immediate difference in the performance of the car. Not one response, not half and half but post after post of yes, it makes a difference.

If this is not some sort of placebo effect on the masses, what exactly is happening to the car that makes everyone believe there is some major change after doing this?

I am just honestly curious.
Surely I can find someone with the necessary equipment to clear the adaptions so that's coming up right after the replacement of the brake switch. No point in having anything malfunctioning before I do that.

The more I think of this the more I believe the adaptions need to be reset. When I bought the car, it had a noticeable bump going from 2nd to 1st as detailed. This was the reason behind doing the fluid and filter change. No other symptoms presented themselves until after I did the filter and fluid change. I have no history of when or if the car ever saw a transmission fluid change in its 120k life and the fluid that came out certainly looked past its useful life. There were no filings of any sort on the magnet in the pan so I was sure this was the way to go.

After the fluid change (actually twice a week apart), the bump from 2nd to 1st got substantially better (about 75% better) and then the other symptoms started showing up. Sluggish 1st to 2nd upshift, the slight bump going into 5th and the squawk heard on a few occasions now. I did get a transmission fault warning one night as I did an aggressive throttle to force the car into a downshift from 6th to 5th so I have not driven the car like that since.

My hope is that the adaptions were so far off that the car has compensated too much and now it has surfaced issues because of it. Resetting the TCM is the obvious next service before I start to worry that I may need to change solenoids in the tranny or have it rebuilt. Then I can circle back to the squawk and see if it still remains.

Thanks for your experienced input on this. I know its a topic that has been beaten around quite a bit but I always follow up on results from whatever I do.

 

Thanks for the suggestion but it certainly won't be that.
I do the majority of work on my own vehicles and have been hands on with the battery a number of times performing various service tasks.

I'm putting money on needing the TCM reset at this point.
Will let everyone know how it goes when I am done with it.

B

 

I gather this is the ZF 6HP26 (as my car has). The dealer tool nowadays can not only clear the adaptations but also can be used to re-learn (re-adapt). They drive the car and an extra person watches IDS/SDD as the TCM learns the clutches and the display shows each as it does. (The TSB is rather old.)

 

Go ahead and have the ZF adaptations reset procedure done. We've had it done twice now on my wife's 2006 XK8, once in July 2013 and again in April 2016. Both resets returned her ZF to shifting normally throughout the gear range. $150 well spent each time....

 

Thanks lads, all very useful information.

Had the car out for a while today and the transmission was acting all up. Weird shifts, got a squawk and finally got a transmission fault. I was babying it too.

I remember when I bought the car, the only issue I noticed on the drive from SoCal to Vegas was the bump going from 2nd to 1st. The whole reason I did the service to begin with. I don't remember anything weird outside of that.

Now I have all sorts of weirdness going on including my second transmission fault / limp home experience.

So it has to be one of the following as far as I can tell:
1) Adaptions were so far off dealing with really old fluid that the TCM simply must be reset.
2) My transmission doesn't like the Mercon SP fluid I used. Highly unlikely since so many others have used the same fluid with no ill effects posted.
3) Somehow I have the wrong fluid level in there or something occurred during the R&R of the fluid pan.

That's all I can think of.
The fluid was definitely way old and when I checked the magnet in the old pan, there was literally nothing on it to mention.

Seriously hoping that the TCM reset helps this out.

My shop has a Autoland Scientech VEDIS II.
Really hoping their unit can do a TCM reset. I only know what they have because I took a picture of it on my iphone one day instead of writing down codes.....lol

Having a look to see what its capabilities are now

 

You definitely need to get the codes read to get the specifics. Don't discount causes unrelated to the fluid. Several times, folks have reported an issue with the ABS reluctor ring on the driver side rear axle. If it is loose (not completely solid with the axle), it reports vehicle speed inconsistent with other sensors, and the TCM/ECM throw all kinds of errors. Easy to check, too.

Best of luck, keep us posted.

 

Great tip!

Will definitely have a look into those things.
It's odd to me that although I had the one issue with the transmission after buying the car (2nd - 1st bump), now that I have done the service, there are a host of issues.

Seems to point to a pretty confused TCM module but I will turn over everything else in the process.

Cheers
Bernie