Not tired at all, keep up the commentary. We'll all be in similar position sometime.

I wish you all success,
Steve

 

OK, Here's the first look at trying out Vehicle Spy;





And Look! There be CAN messages...



And that CAN message at the bottom seems to increase when the XKR is moving. I have named it appropriately here. I found that the first two bytes are Front Left, thet next two are Front Right, the next are Left Rear, then Right rear.



So I spent a couple minutes making an easier to read display to decode that particular message. It still needs some cleaning up, but the green bar graph and gauge are suppose to indicate each wheel speed, witht he numerical display on the gauge being speed of each in km. The most handy thing I think will be the histogram plot on the right, it should make it very obvious to see which one is not acting like the other three. It's pretty neat, a quick brake torque ramped up the two rear wheel signals, turning to the right made the two left wheels go higher than the rights, etc, so I know I have them mapped correctly.




I also filtered on only this CAN message, then saved a log file so I could review the entire drive to work in Excel...

I think this will help me, but I doubt most of the rest of you will ever be able to use it. Hopefully it will at least be interesting.

 

Nothing beats real data eh? Good luck with the continued research! Any chance Vehicle spy can show the PIDs it is seeing?

 

I can request any PID's I want to see (and a TON of other things) However V-spy isn't requesting anything for what I am doing so far. It is simply displaying the messages that are already flying around on the bus.

The wheel speed message is just automatically sent out every 7.7 mS, so I don't see it's storage location in the ABS module.

The V-spy is more of a development tool. (Jaguar corporate is listed on their website as a customer of this tool, so I imagine their engineering group uses it similary to the way I am, however they have the benefit of knowing what the messages are without figuring them out.) So it is low level, and can be dangerous if you don't know what you are doing with it. I can construct messages to request any data that can be provided over the bus. I can see anything on the bus. I can reprogram things, and change settings. In short it has the ability to do anything that ANY scan tool on the market does, and more.

However all of the above depends on knowing WHAT to change, and the format used to do so. So I am limited, but what I can figure out on my own. One thing I can do easily, is connect this WITH a scan tool and see what messages are used to request and clear DTC's, and simulate those messages.

 

There are threads all over the place about this debate - I'm doing fine with Mobil synthetic which meets the same standard, though some insist only the stock fluid at seventy bucks a quart will do. To each his own.

But yeah, you should quit driving it and have someone who KNOWS how to properly fill this transmission do the job. There are also threads out there on this - very specific and temperature sensitive exercise that AAMCO might not know.

By the sounds of things you're already on the way to needing a replacement. To get an idea of the cost, check eBay for some shops that sell decent rebuilds with warranties (don't forget the core charge). I found a few - day I know I'll need one. And run away from anyone who offers to install a used transmission.

 

This is an XKR - Different trans than you have.

I'm confident the fluid level is fine now, and really I don't think it was ever too low. It was old, and I'm glad I changed it, but the fluid, and the trans for that matter are fine.

I have an electrical issue, that I have been detailing over the last page or so. The Mercedes trans in the XKR seems to be quite a bit more dependent on the wheel speed sensors than the XK8 trans.

 

I think we have a winner;



It appears the left rear wheel speed signal flaked out while I was turning right. I kind of felt the stabilty system or something kick in, but I didn't get any warnings. I've been kind of suspicious of the left rear, as it was giving small spikes once it a while.

Also I am suprised at how sensitive these wheel speed readings seem to be. Those jagged sections towards the beginning of the trace (between 1405 and 1406 seconds as listed along the bottom of the plot) are from me hitting some roughly patched potholes. Also I once in a while feel like there is a tire out of balance, and glancing at the laptop while driving, I swear I can see a corresponding ripple on the plot. I'll dig into that more and see if it is one wheel with the ripple, and get it balanced to see if it changes.

Right now, I have a left rear wheel speed sensor to change...

 

...gonna swap it with the right side and see if it follows it? If it does...sensor, if it doesn't...you guessed it, wiring!

Great diagnostic tool! When the wheel speeds no longer interest you, could you see if you can find the PID for the transmission fluid temperature sensor? I'm not sure what you need to help find it, but If I can do anything, let me know. Borrow the AE, whatever. I'd like to give everyone that ability through Torque. Need the PID, then going to figure out the equation to attach to the measurement (unless you want to undertake that also )

 

I didn't think to swap them side to side. I already swapped my front ones with the two used ones I picked up from the XJ, so I put one of my old front sensors on the left rear, and ran out to see some friends, about 60 miles - no issues. I monitored the speed sensors the whole ride there and back. I also used the cruise for half the ride back, and purposely took a bumpy road to try to set it off. So far so good.

As far as the PIDS, I'll see what I can do. Do you know if the trans temp is sent out to other modules without it being requested? If it's sent out on the bus already I should be able to find it.

The thing with PIDs, they are basically like a memory address. Sometimes the modules are programmed to dump the value of that memeory address on the bus periodically, like the wheel speed values. Some times you have to request the value if it is something only used occasionally for a diagnostic. The PID numbers are 4 digits in hexdecimal, so if I have to request it, that's 0000 - FFFF to try. I won't know what I am getting back, so I'll have to have an idea what the trans temp is to know what value to look for. Sometimes requesting a PID that is not used will tell you it's invalid, so that's easy to know it's wrong. Other times with an unused PID you just get a random number, but how do I know if it is a random number, or if it means something?

It is much easier if there is a tool that is already reading trans temp. I could see the PID being requested. Anyone around Southeast MI have a Jaguar test tool I could borrow for an hour?

The scaling formula might be straight forward. Scaling the wheel speeds was easy. Vehicle spy can convert from Hex to Decimal on the fly, so watching the decimal number and comparing with the speedo I realized that the decimal number was 1000x the speed in kilometers. So the number sent out is actually speed in meters per hour, or kpH to the third decimal point. Hopefully the temp will be a similar move-the-decimal-point conversion.

 

i have the same noise it sounds like slipping disk or a bad torque converter it moves slow until about 3000 but once moving its fine but still makes that slipping disk noise the scm displays gear box fault and the check engine light is on
also i went to get emissions done and after they tested it cleared the codes and ran fine for like 60 seconds so what do you guys think

 

Amazing forensic work Andy.

I learn so much on this Forum.

 

The XK8 is a different transmission than I have in the XKR. It has a known issue with the A drum failing. It also could be need of a fluid change. Check the FAQ at the top of this forum, and there are links in the second posting to several discussions about the ZF 5HP trans in your XK8. Also if you get the warnings back don't clear the codes, have them read and share them here. The codes are big clues as to what is wrong.

As for me, I got a few more moments of flakiness from the left rear wheel speed sensor on the drive to work this morning...

Also looking at the appendix section of the elecrical guide, the transmission oil temp message looks like a periodic message sent out by the trans control module to be used by both the ECM, and Instrument cluster. I should be able to find it.

 

Very interesting post...thank you.

I think the cables & connectors the sensors connect to go open or intermittent as often or more than the sensors themselves...don't overlook that.

 

Still flaky and its got a different sensor? Sounds like wiring or those connectors like WhiteXKR mentioned above.

BTW, this is the very same sensor (LR) that Gameblaster over here in Dallas was experiencing on his car, it was always dropping a few mph behind all the other sensors...in addition to his messages of trac control/stability control and other failure messages...resulting in a newly rebuilt ABS module. Of course, we haven't checked to see if the LR wheel speed sensor has returned to normal.

And Andy, I should have my AutoEnginuity scanner w/ enhanced features back in a couple weeks. If you can't find the tranny temp data by then, and the corresponding PID, I'll ship it out to you so you can monitor it side by side...well, figuratively that is. I'll check back later to see if you make any progress.

 

Well, I found....something...

I decided to spend today getting to the bottom of this. So I supported the rear end of the car with the wheels off the ground and put it into drive (traction control switched off) so I could wiggle test all of the electrical connections while watching the wheel speeds to find the bad connection.

At the sensor - no dice, at the module - not there either. OK follow the sensor harness to where it goes inside the car. Looks OK so far.

Pull the trunk trim and there is a connector where the sensor harness joins the body harness in the spare tire well. Jiggle that while running - still no luck.

Follow that branch of the harness over to the main body harness and...What the hell?



Looks like someone was doing electrical work with an ax!

It's hard to see, but there are several bare wires, and one wire (white with green - I need to see what THAT is) is cut completely and may have been occasionally hitting the fuel tank.

I stopped the jiggle testing there and am about to get started on wire patching.

I'm kind of glad I DIDN'T take this to a trans shop... I also kind of doubt that anyone with the same symptoms as me will find the same cause.

 

OK the harnesses are all patched up, but I have my doubts about seeing the end of the gearbox fault.

I don't think the left rear wheel speed wires were the damaged ones.

But I did find about 7 wires with bare copper that got taped back up. And the wire that was cut completely? That goes between the "Transit Isolation Device" and body processor module. I am not sure it was even used.

I did however unplug, inspect, and reconnect two plugs that the wheel speed sensor circuit goes through. All of the connections appear to use gold plated terminals.

I was hoping the wiring would also get my rear park sensor system functioning, but no.

My CD changer is now working again however. Not because of the wiring fix though. Since I had everything in the trunk apart I removed it, opened it up, and cleaned it a bit. Then I re greased some of the mechanisms with lithium grease. So far so good there.

 

Left rear wheel speed sensor still acting up. I felt the stability system kick in as I was leaving the parking lot at work today. So I hooked up the V-spy again for the ride home, and saw the same flakiness on the left rear.


So I jacked up the rear of the car again and went for the jiggle trick on the trunk harness to body harness connector, as well as the body harness its self where it goes over the right rear wheel arch into the body. There seems to be something there. The actual connection seems OK, but moving the harness way up over the wheel well would occasionally make the sensor drop out.

So I guess tomorrow I'll start pulling the rear seat and interior out to see if the body harness has rubbed through more insulation somewhere in that area.

 

Hooraaarrr

 

OK I found it for sure, and I mean it this time!

I removed half of the interior of the car yesterday chasing the harness. I had the rear end jack up, and the car running in drive, and I wiggled every part of that harness all the way up to the next connection under the center console. Nothing.

Then as I was sitting contemplating my next move I heard the faint whooping sound again, and with it the speed signal dropped out. They are related! It makes sense, both the noise, and troublesome wheel speed sensor are left rear.

I got out of the car and waited for the sound again, and heard it a couple more times, it seemed to be coming from the knuckle/spindle.

I shut the car off and gave the rear wheel the up down wheel bearing test, and got a LOT of movement, probably 3/8" at the edge of the wheel. I tried the passenger side, and no noticeable movement at all.

So after taking a look at the JTIS procedure I decided that changing the rear wheel bearing is not something I want to do. But this morning I decided to take a look anyway. I removed the left rear wheel, and put the spare on there so I could lower the car to the ground to hold the hub in place while I turned the hub nut.

I got out my biggest breaker bar and prepared to fight the 300+ N-M torque, but the nut was barely on there. That's not good. So I decided to tighten it and see if that would help. I turned it probably 90 Deg tighter than it was before it felt like 300 N-M. Then I jacked it up and tried the wheel bearing test - no movement.

Then I removed the hub nut again, and the brake disc, and the spindle quite easily came away from the axle shaft. I reached in side and grabbed the ABS tone ring and it came off in my hand! This is suppose to be a press fit onto the hub, and it was just laying in there loosely.

I think the speed sensor and wiring have all been working correctly all along. Its the tone ring that has come loose, and sometimes stops spinning at the actual wheel speed! That would bee the whooping noise I hear as it is slipping, and would explain why I sometimes seem to hear it when the other issues popped up with the trans, and ABS.

Pictures to come.

 

Wow, you are the man! What a search, you are an inspiration to say "never give up". Well done.
Steve