Does anyone know what U codes are? The AE de
scription is communication bus failure. That does not tell me a lot and I can not find anything in JTIS on Ucodes.

Thanks

 

There are dozens, maybe 100s, of them!! Which specific one(s)?
Also, did you try google?

And again, they depend on the model year of your car which depends on the VIN. Please get on with posting it.

 

U codes are network faults of some type. There are a ton of U codes, as mentioned.

 

VIN=M37734
U1131
U1262
P0460
P1233
I don't understand this!! Car runs great except for very intermitent failsafe mode and throws P1584. It seems that I must have a SCP bus failure. Any suggestions to narrow down which module???

 

you needs to lists modules that threw the codes, which ones and then the fun begins. it can be modules and or wiring. This stuff seperates the techs from the mechanics.....unless your a customer because then "the computer tells you whats wrong with my car, how hard can it be to fix!"

 

That looks to be a 2001MY-type car, but at least it's before the facelift. So you likely have the modules and bus structure that implies. As Brutal says, which modules? If those are all from the PCM:
U1131 not listed for the PCM as fas as I can see
U1262 (an audio-related fault)
P0460 fuel level sensor cicuit malfunction
P1233 (another fuel system fault)

As Brutal says, you want a tech i.e. someone competent, experienced and with both tools (especially electronic OBD) and a brain.

You could try what I put in the DSC system fault thread if you've time and are competent and persistent. You may need some expensive tools, too. (Thus, a tech lol)

 

LMAO....so true.

 

"you needs to" ????? WTF I have to remember, proof read, and no wine or beer when posting

 

Thanks for all the tips.
The codes are coming from the instrument pack and fuel sensor A which is monitored be the RECM. I am thinking that somthing is actually killing the SCP data bus intermitently. I guess it could be a faulty module or a wiring short to ground. possibly a dirty connector but I doubt it. I had the AE connected and recording yesterday when the fault occured but nothing showed up unususal on any sensor at playback. It gave a fail safe message and MIL for about 40 seconds while doing 60MPH on the interstate. The fail safe message and MIL went off and the engine then ran normally. Left code P1584 and the P and U codes posted earlier. I am now going to connect a scope to the SCP bus and monitor while driving and hope that it will fail while driving so that the memory scope will record the SCP waveform at the time of failure. I may connect the CAN bus to channel 2 on the scope just for reference. I will keep posting as events unfold.

 

Now you really surprised me as the diagrams I've seen appear to show your car doesn't have CAN.

 

Issues with pins and connectors are not corrosion, but loose pins. You have to to a "drag test" on the pins. These are the biggest issues with scp, can intermittent faults. Also when other modules have issues with communications, but 1 module says everything is fine, its usually that module thats the culprit. If youre shade treeing and dont have axcess to pin repair kits, cut out the suspected wires and splice together outside the connectors. Can always be cut apart later if someone has to seperate and reconnected. But it will eliminate that connector set of pins as the issue. but youre in for alot of diag work, these type repairs are seldom clear cut

 

You are actually right. I have been calling it CAN but it is actually Jxxxx.
Sorry about that.

 

I HATE when people don't mention when a problem was solved, but I'm afraid I have to re-open this thread. I have a 2000 Jaguar S-type V8 N/A, and I have all the same codes.

U1131 SCP (J1850) Invalid or missing data for fuel system
U1262 SCP CJ1850 Communication bus fault
P0460 fuel level sensor circuit malfunction malfunction
P1233 Fuel System disabled or offline

The combination problem here is causing the general electronics module and the rear electronic control module to signal the fuel relays (G signal), this is causing a drain of approximately 600 MA on the battery at all times. The question is, which module is sending a signal to one of these two computers (once a ground is received, both modules show ground signal on) to turn on the fuel relays? Since I have codes for the cluster, I'm starting at its connector and pins in the morning. Some of you have seen me here, I'm a Jag Specialist, WE WILL HAVE AN ANSWER. Eventually... But I'm off the clock for the day, I'll keep everyone in the loop.

 

Of the about a dozen modules, which ones have which codes?

 

U codes are stored in both the General electronics and rear control modules. P codes are of course in the PCM. The problem appears to be in the rear control module. The signal is NOT on from the instrument to the module, so it is sending a signal it shouldn't be. I have also found that the rear lights are doing all kinds of crazy things, so I am getting a used rear electronics module.

 

Thanks for your effort to report the repair. This one does not sound easy or even possible for a home guy!
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Well, getting the codes is easy as there's now a choice of OBD tools that will read all the modules. Changing an RECM is easy I think.

I don't currently see why it's the RECM but as it's not my car that's not a surprise.

 

RECM is signalling the fuel relays at all times, causing a drain on the battery (turns all 3 relays on) it has a 600 mA drain. I fit a test module, drain is down to 10 mA.

The RECM also works the lights, which are doing crazy things.

 

Diagnosis took approximately 4 hours, very complex issue.

 

At least you had clearly wrong things to guide you. I wonder if the module's been wet or the car jumped (or welded).