Driving home, engine begins to run really rough, displays shows Engine System Fault, DSC System Fault, Cruise Control Not Available. Limp home about a mile....and yeah engine is really running rough. Pull the codes and get the P2135. However in pulling the code, with the ignition to ON, the throttle body is making a steady noise. I assume this is the motor that rotates the throttle plate, right? The throttle plate moves freely...so nothing is jammed.
I had replaced the intake air hose last year as it was cracked in several places. Checked the new one and no cracks, so not the problem this time.

Are there any checks of the throttle body I can do?

Thanks

 

Do you have another code reader you can try?

I can't find any P-codes above 1799 in the DTC list

 

P2135 shows to be a generic code for Throttle/Pedal Position Sensor/Switch A / B Voltage Correlation. Let me try my other scanner...see if it shows any difference.

But from the noise the throttle body was making....it is probably the motor inside.

 

How many miles on your car? Be sure to check/listen to the crankcase ventilation hose for a possible leak; they deteriorate over time and will throw the display errors you mention. Gary VanRemortel (author of the XK8 Bible that we all study daily...) offers superior grade hosing and will rebuild yours if you send him your connectors.

 

No Go on the other scanner, only reads P1000.

Mileage is just under 105k. I was not aware of the crankcase ventilation hose....I will check that....THANKS.

I removed the throttle body....sure needs a cleaning... as does the intake....but that will be another day.

 

I guess it's possible that the code is valid since your car is a late model and there's no update on DTCs since the 2003 list, AFAIK.

Slightly different beast, but my TB does make a slight buzzing noise whenever the ignition is on.

 

Perhaps I just never heard the buzzing noise before....hope so....really do not want to replace the throttle body.

I removed the PVC hose....no cracks in it. Going to try changing the O rings on each though....if I can find some.

 

Thankfully, P1000 is a status, not an error code. It typically means that the battery or powertrain control module (PCM) has been recently disconnected; it should clear by itself just driving a few miles. Have you disconnected the battery lately? A hard reset might be in order and wouldn't hurt. Are you familiar with the steps?

Jaguar Hard Reset
Short Negative connector to Positive for up to 30 seconds (or leave the Negative cable off for 30 minutes). Tighten Negative post back onto battery.
Turn ignition on, don't start.
Reset windows.
With switch in position II, (not started), slowly press accel pedal through kickdown detent to the floor & hold 5 seconds. Release pedal and repeat 1 more time.
Let off of pedal.
Start engine, idle until operating temp is reached. Switch engine off.
Restart, idle for 2 minutes.
Apply foot brake, shift to Drive, idle for 2 min.
Then, drive around for 5 miles of varied conditions.
Don't forget to reset clock, audio, and climate controls

 

Yeah I know that P1000 is just status. However I have not had the battery disconnected lately....has been over five years since I replaced that battery. The DSC fault is letting me know that battery life is short.

I will do the hard reset after I check the TPS resistance values. I am suspecting the TPS is worn, checking the resistance as I move the throttle plate will probably confirm this. It appears that a replacement TPS is available now and not even expensive. Denso part # 198500-3300.....Amazon shows like $36...

Thanks the hard reset steps....did not have the saved anywhere.

 

Not a bad time to check and adjust the throttle cable to 95-96% before kickdown and 100% at kickdown, while you're at it.

 

Have to admit that I have not ever checked the throttle cable, nor how to adjust it. Time for me to do some research into this.

Just to be sure here....mine is a drive-by-wire system...no throttle cable to the throttle body.

 

As you say 4.2 are fully drive-by-wire throttle. This is the procedure for setting/calibration.



5, setting WOT, covered in JTP939

After battery reconnection, the engine management system must ‘re-learn’ the limits of throttle pedal travel.

Re-programming is done with the ignition switch in position II as follows:

Do not start engine.

Slowly press the accelerator pedal fully through the kick-down de-tent to the floor. Hold 5 seconds

Release the pedal and repeat the action.

 

Well....
I removed the throttle body and cleaned it. I did some resistance checks of the TPS, pins 1-4, 1-2, 1-3...all values were quite a bit lower than the ones I found on here that someone posted. Same Denso 198500-3300 TPS.

I put the throttle body back on and went to start the engine, but after the System Check the same three failures came-up: Engine System Fault, DSC System Fault, Cruise Control Not Available, plus both red and yellow warning lites were on. Started the engine but of course it was in limp home mode, would not rev-up at all. I thought the failure was heat related, guess not!

I currently have the negative battery terminal off, letting is set....see if I can even do the hard reset....probably not going to be able to if not able to run engine.

I did order a new TPS but doubting that it is the solution. Probably looking at getting a new throttle body....but without more diagnostics.... do not just want to replace expensive parts without reason.

 

Don't overlook that the code is set because there is a discrepancy between one of the Gas Pedal position sensors and one of the Throttle plate position sensors.
So it could be the pedal sensor, throttle sensor, powers/grounds to either or the cable in between either to the ECU
Before firing the parts cannon at it, first take a look at the pedal and the wiring for obvious issues. Then test the resistance of the two( three?) potentiometers on the pedal at off, 30%,60% and see if they match the spec - they will usually have different resistance curves. Same with the throttle sensor output.
Not sure how easy the ECU is to get to on the 4.2 but (key off) check the resistances on the appropriate wires there too. Also check the sensor ground wires are good.
Sorry I don't have a wiring diag for that model but you can probably find one.

 

Agree... Fault is either what the accel pedal position sensor is telling the ECU or what the TPS is reporting to the ECU what the throttle plate position is.

I suspect that during System Check the ECU commands the throttle plate motor to move a few degrees and the TPS reports to the ECU that the throttle plate moved those few degrees. In my case the ECU is not getting the correct information.

I did check the wiring at the pedal position sensor, TPS, ECU, all seem good.

What I would like to do is apply the proper voltage to the throttle plate motor to see if it moves.....but need a wiring diagram, which I do not have....may be I can find one.

Oh and did the hard reset...but no change. When I turn the key to ON and let the System Check run, the same faults are displayed along with the red and yellow warning lites.
Whatever has failed is a hard failure, not intermittent now.

 

That's a good point about the start up test, though I suspect it will want to see the correct pedal off resistances too.

Jag repair has wiring up to 2003, plus the workshop manuals might have sensor data in the pinpoint tests
JagRepair.com - Jaguar Repair Information Resource

The Throttle body will be driven by a square wave with the duty cycle altered to balance against the return spring to give an exact position with feedback through the pots (that's the whine as the motor and spring fight each other). I drove one on the bench with a simple square wave generator. Not sure what the max duty cycle expected is but I would be wary of shoving 12v up it until I knew!

 

Again agree....the throttle motor is driven by a PWM signal. Just do not know if on the positive side or return side, or what the amplitude is....so not going to even try applying a steady 12V.....that would be a disaster!

I checked JagRepair, did not find anything that I could use. Spent some time searching for a wiring diagram using various keywords....found nothing so far.

The saga continues....
.

 

AAARRRGGGHH!!!!.....now I know why the fault has become solid....I did not reconnect the throttle plate motor connector.....AAARRRGGGHHHH!!!!

Will try the hard reset again....this time with the motor connected.

UPDATE: so now all faults are gone except for DSC. After doing the throttle reset, started engine and had the Check Engine Lite on...which was not on before. But was probably due to me not having the throttle motor connected. Cleared data to turn off the CEL. Engine running fine, same as before the limp home mode hit earlier this week.

Will still be replacing the TPS once it arrives next week. Until then will only be driving it short distances....see what happens the next few days.

 

Okay...something a bit different.
Cold start this morning (garage temp about 40°F), no problems, drove 12 miles with no problems. Arrived at my destination, car sat for a little over an hour in the parking lot. Get in, turn key to ON, let System Check run, see both yellow and red warning lites on...start engine....get the three failures. Drove for about 100 feet. Stopped, shut off engine. Re-started...all was fine, drove home with no problems ( four miles).

Does this give anyone any different thoughts????

 

Random warning lights after a cold start usually indicate battery issues. An hour outside at "flippin cold" will mean a big battery draw from an already cold challenged battery. Short journeys with lights/heater motor/heated screens/wipers etc will not help as it will not be charging much if any.
If you have a min/max meter take a look at battery voltage on start , it should not drop below 9.6v - if it does it can give the electronics a fit hence lots of warning lights.
You might get away with just an regular overnight charge up or the battery might be on the way out, might be worth getting it load tested.