Hi all
Bit of background - car (2000XKR) is fairly inactive but kept on an optimate charger. I've had issues with the instrument cluster and have replaced it with a secondhand unit. For some time I've had an intermittent high gearbox temperature that seems to clear after cycling through the J-Gate.
The car is not unknown to get a misfire code now and again, this is only when cold after sitting for a while, I assume water ingress/condensation into the coil covers. When these are cleared, the restricted performance goes away.
I know I have an a/c leak which I noticed in the summer, and now it's winter I noticed my heater motor had stopped working (blowing a fuse in the engine bay), which turned out to be the alarm sounder - disconnected that and the fuse no longer blows and I have warm air.
Since that alarm sounder disconnect, I have a Restricted Performance that doesn't go away when I clear engine management codes.
I am getting a knock sensor low voltage code that keeps appearing - p0327, but again if I clear it, the restricted performance stays.

Other codes that I'm getting from an ICarSoft Scanner are:
U1260 SCP (+) circuit failure, and U1261 SCP (-) circuit failure (I don't know what the SCP circuit is)
B1202 Fuel sender circuit open
B1232 Inclination sensor self check fail
U1135 Ignition status not obtained
U1041 SCP vehicle speed signal invalid or missing data

Some of these could be from during the instrument cluster problems; the iCarSoft scanner couldn't reset some of them, and I've since done a hard reset but haven't rescanned, I will do that soon.

Of these, I'm thinking the U1041 might cause restricted perf, not sure about the P0327 - I thought it needed a couple of cycles to throw the code, but this restricted performance doesn't go away after switching the ignition off (as I've had previously), or a hard reset.
Any ideas on what to look for first?
Could I have caused U1041 if I've inadvertently knocked the wheel speed sensor when getting the front wheel off to disconnect the alarm sounder?
much obliged for any help. I'm pretty poor at electrical fault finding.. wrong car I guess!

 

If that was my car I would replace the KNOCK SENSORS and the gearbox CONDUCTOR PLATE for starters.

The gearbox temp sensor is built into the conductor plate.

The network diagrams are fig. 20.1 in the electrical guide S2000_XK8.pdf

 

if you replace the conductor plate, search out a genuine Mercedes part. The aftermarket parts are junk. I am kicking myself twice a day for replacing my original conductor plate “just because I was there” and it was getting old. No problems with the original part.
But the aftermarket replacement gives out spurless / false HIGH TRANS TEMP warnings occasionally.

dont do like I did. Use quality parts.

Z

 

thanks both, I am less concerned by the high gearbox temp problem, although it is annoying it is currently temporary and has been happening for ages (I stumbled across an old post of mine mentioning it several years ago!). Definitely on my list but right now I'm more concerned about notbeing able to get it through an MOT if I can't clear the code. I know the geearbox temp isn't actually a high gearbox temp, if that makes sense.
Anyway, I am now fairly sure the unclearable code is a "real" knock sensor issue, as I can see a pending code that comes back immediately after clearing, and changes to a "high" code when I disconnect the knock sensor, then back to "low" when it's reconnected.
Interestingly I seem to have a collection of small pieces of the foam insulation from between the supercharger and block all around the knock sensor - I am suspicious that I might have had some rodent activity in there. Could just be degradation, but also might not be.

So my next question is; any tips on replacing the knock sensors without removing the supercharger? Is it even possible?

 

SCP is standard corporate protocol. It is the network bus for communication between the body modules. I think you said you didn't have the problem until you disconnected the alarm. If so, that might be something to do with it. I don't recall for sure. But I think the box with the speaker Infront of the right wheel has part of the alarm module in it. If so , it wouldn't be connected to the SCP bus.
As for the restricted performance, what kind of fuel you have in it,? My 2000 xkr is very picky about fuel. It likes octane. If I put anything but highest octane restricted performance stays on.. I don't know about what codes it has. I haven't been able to get a scanner to communicate. One of these days I'll have to figure out why. For now if I keep high octane fuel it's fine. You also said it sits alot. If you do have high octane fuel in it, maybe it's degraded from age. I'd try draining the tank and giving it some fresh fuel. This gas they sell nowadays doesn't have much shelf life. I've had it go bad in a couple weeks.

 

You cannot replace the knock sensors without first removing the supercharger.

On October of 2020 I had a knock sensor fail on my 2002 XKR about 158,000 odometer mileage.

with ongoing back pain issues I was looking for a HACK repair that I could use to put off the supercharger removal.

So I did a complete share tree hack that kept the check engine light off and the car has been running completely normally ever since . That was 3 1/2 years ago, and approximately 30,000 miles ago.

the car is my daily driver and it’s driven as hard as I can and still keep a
drivers license; ie I do accelerate to the red line whenever possible.

I use the best available 91 octane pure gas fuel and have yet to have any indication that the relocation of the knock sensor is causing any damage or performance reduction.

But it’s a hack, pure and simple, if you care to read the post below you’ll see the criticism that this hack generated.

yes, I’m lazy. Someday I might fix the knock sensor properly. Likely when I have a leaky octopus hose. Until then, I’m just going to keep going against the tide of conventional wisdom.


https://www.jaguarforums.com/forum/x...r-hack-238806/

Z

 

^^ Yes, there's quite a lot to do to get to them on the 'R.

You could follow zray's route initially to confirm the sensor is faulty. If you do elect to do the R&R, I'd recommend replacing them as a pair as you don't want to do this job twice in quick succession. It's also a good opportunity to replace the valley hoses 'while you're in there'

As noted, SCP is a (Ford) network protocol over which some of the car's modules communicate. The others communicate over the separate CAN (controller area network), with the Instrument Cluster acting as a 'bridge' between the two so everything can converse.

I can find no detail on the 'B' and 'U' codes you list until the 2003 documentation. I'm not sure if it's possible to rely fully on Jaguar not having changed the meaning of those codes across the years, but, if so, they're mostly SCP-related and could relate to the issues you've had with the cluster. According to the DTC lists, none of these codes will set the MIL.

The 'intelligent sounder' you've disconnected is not on any network.

Does the UK MOT test stick sniffer pipes up the exhaust and not read OBD codes?

 

Plus, genuine parts aren't even that much more expensive from mercedes. Came as a bit of a surprise to me. Did my transmission connector recently and decided to leave everything else the hell alone seeing as its all working right and it had a trans fluid and filter change 15k ago.

 

Also, trickle charger or not, what are your battery volts when coming off the trickle charger prior to starting? Some battery keepers aren't the kindest to AGM batteries and these cars hate having a weak battery.

Im also drawing a blank on those codes for a 2000XKR - could you go back and run the diagnostics again and triple-check you picked the right year and model? What model of icarsoft scanner do you have, and can you confirm the software version number on it?

 

I had the exact same problem the OP had on my 2001 XKR - no heater, blown fuse and it was of course the active sounder, which I removed, without causing any other issues. I looked into replacing it with a non-Jaguar siren, but it isn't as simple as a direct on/off connection, it does appear to be on one of the buses. According to the Electrical Guide it is on the "ISO serial data bus":-

If that is the case on the 2000 XKR, it would certainly be worth making sure none of the wires in the active sounder connector are shorted/have water in them etc.

 

Thanks, dibbit.
I'd missed that, although Murphy's law the EG doesn't mention the sounder in the description until the 2001 edition

 

The active sounder is connected to the SCP network. Look on page 132 of the 2000my electrical handbook. When you have multiple problems and or crazy things happening it's good idea to check grounds. A loose body ground can cause nightmares

 

No, certainly not directly, and there is no reference in the SCP message list to its being a node. Single-wire comms with the BPM.

Other than the check dibbit suggested above, IMO it's not relevant to the OP's issues as the car doesn't care if the sounder is missing.

 

​​​​​​Ok so the circuit diagram doesn't know what it's connected to. I can't say about any descriptions. I've not been able to find any. I found a couple things like the electrical manual on jag repair something.com But most of the pages on that site won't even open. Says they are down. Nobody saying anything about fuel. Fuel is definitely relevant. Fuel will cause knock. And a knock on this car will make it undrivable. And the fact it's been sitting shouldn't be overlooked with the crap sold for gasoline. Recently I had 5 gallons sit for a week in a closed container. After a week nothing would even run on it. Tried it in my truck, tractor, lawnmower nothing. Was good when I bought it. Gasoline has always degraded with time. Turns to parifin. Bad gas , especially in a supercharged engine causes detonation which is picked up by knock sensor. From my experience knock sensors don't go bad often. I've been doing driveability since early 90s. Ford and ASE certified master tech. I've had to replace knock sensors because someone broke them. I've seen many times people replaced them and didn't fix anything. The number I've replaced that were actually bad I can count on one hand with fingers left. It usually comes out to be wiring issues or something fuel or timing related. And the "hack" with adding a sensor. If mounted properly could work fine. Key is mounting properly. Needs to be mounted in proper location( correct bank) And has to have a good ground. A bracket not being a good spot. Sensor must have good ground to operate. Must have good engine ground and good body grounds. After years of operation ground straps get damaged , removed , etc causing all sorts of issues.

 

Thanks everyone for your input and suggestions! I'll do a rescan over the weekend and check I set the model year correctly, pretty sure it was set to 2000 though. No idea what year the scanner is, these days I think I did something 6 months ago and it was more like 5 years!
Anyway I have new knock sensors and will replace them properly when I get some clear time, it doesn't look too bad, just time consuming.