S Type problem with fault codes

[fitman207]

Hello my handle is fitman207

Please can anybody help me with the following printout I have had from an independent jaguar garage. Everybody says something different and I can't get to the root of the problem. My car is coming up to the MOT date and I urgently need to address this problem. Here is the print out:
Jaguar – EO51 AHY
S Type – 3 litre petrol
Year of manufacture – 2001
Fault codes done by independent jaguar garage:
Poss – ABS Module + Pump
ABS
C1095 – Hydraulic Pump Motor – circuit failure
U1262 SCP command fault – (audio related fault?)
P0228 – Throttle position Sensor C high input.
P0229 – Throttle Position Sensor C intermittent.
P1574 – Throttle Position Sensors – Disagreement between sensors.
Throttle Body?
End Printout

There is nothing wrong with the brakes. I have changed the entire ABS module with identical matching numbers twice!
The engine management light is on, the ABS light is on, and the computer readout on the dash says the car is in limp mode. However, the car happily accelerates to well over 80mph, it runs fine.

Could somebody please tell me where Throttle Position Sensor C is located on the vehicle, in order that I can change this. Is there a way of testing whether this sensor is working properly or not? I have an electrical test meter.

I look forward to receiving a reply. Many thanks for taking the time to read this.

[J44EAG]

I would begin by disconnecting the +Ve battery cable for twenty minutes. Then reconnect, reset the radio and the clock. That is known as a hard dump and will clear the computers of a mass of accumulated electronic junk. If the check light, MIL light or message centre still show a fault, then an issue still exists. Do this first before going further.

Disconnect the plug at the throttle body, exercise the connection,by plugging and un-plugging several times. Crud can build up on the connector pins. Do the same at the throttle position sensor on the throttle body and also at the throttle pedal. All can get electrical corrosion hot spots given age. Try that after the hard dump. Disconnect the battery again to clear faults which may have again become present if the car has faulted again. Sensor C would appear to be the throttle potentiometer on the throttle body. The fault may not be the unit but could also point to a bad connection on the plug and socket. Infrequent failure of the throttle pot sensor is not unknown. A couple of Torx head bolts secure it to the throttle body. Also clean out the throttle throat with carburettor cleaner. They get filthy and sometimes cause the throttle plate to either not shut correctly due to a build up of baked crank case oil sludge. The throttle when cleaned, should shut with an enthusiastic clunk as the spring rapidly springs it shut.

The throttle pedal can also give issues. What sometimes occurs is that the pedal unit potentiometer gets damp. Removing the pedal from the car and placing on your central heating boiler can sometimes effect a cure.

Try those ideas first before spending any more money. It is worth noting that often the simplest of issues can cause multiple fault codes to be generated.

Mike K

[Martec]

I had something similar to this a few years ago, a horrible wet day just before Christmas and the car went into limp home mode. I had previously had red lights and got the codes read.

I found an odd reference to this and the solution was to undo the two screws holding the throttle peddle in and disconnect the cable. Then put the entire peddle ontop of the boiler over night, the problem has not reappeared since and all the other odd fault lights disappeared.

It turns out that the peddle and the throttle body have three reostats fitted to them (sealed) but only the throttle body under the bonnet is supposedly waterproof. The peddle isn't so damp in the car gets into the reostats and gives false reading and when comparing the three readings from the stats the car gets upset and throws a hissy fit.

A cheap solution.

Brian

[fitman207]

Hi Mike and Brian and all who are reading this. Thanks Mike and Brian for your kind help. I got a second hand tested part TPS from a parts dealer. The TPS part numbers on the back of both sensors are identical. I changed the TPS and the ABS light went out.

However, the Traction Control light is still flashing and the moment you pull off and apply the brakes the ABS light comes back on.

Switch the engine off and then re-start the car and no ABS light until you start to pull off and apply the brake. Then the ABS light comes back on (not flashing). The dash still gives a "DSC system fault" reading.

Can anybody shed any light on this please? I look forward to hearing from you.

Kind Regards - fitman207

[J44EAG]

I would now be looking at battery condition. ie terminal voltage of around 12.8v as a minimum, engine off reading when cold. Batteries need to be near perfect to run these cars. Batteries can die through lack of terminal voltage, a lack of capacity, or a combination of both. How old is that battery? Time takes its toll.

Having been involved with this type of Jaguar for over twelve years now, I would be suspecting the battery as a known prime cause of the issues you may have. I would disconnect the battery for at least twenty minutes to wipe historic fault codes from the computer system. This can often clear issues. If that fails, then I would be looking to replace the battery. A battery voltage drop test using a suitable tester will confirm battery condition.

You might also try charging the battery for a few hours using a mains powered battery charger. Restoring battery voltage will enable the start up diagnostic in the car to complete satisfactory. Failure to complete the diagnostic is usually down to a duff battery and frequently results in ABS/DSC type antics like you have seen.

As regards electronic handbrake oddities, this can again be due to an unstable battery platform.

Mike K

[classicmorrisman]

Hi there!

I'd just drafted out my message and then saw there had been more activity on the subject which is leading me to think that I might have a duff battery as well.

Basically, I was wondering whether disconnecting the battery for a few days might do any harm (I can't see why it should).

We're going to be away for a week and have use of another car. What I thought I would do would be to charge the battery right up (it's a heavy duty Exide, but I don't know how old it is) then see how things go before a) installing a new battery b) taking the car in for diagnostics. No obvious signs of dying battery - engine turns over lively enough and lights are bright.

Car runs beautifully but it's a bit unsettiling seeing all these "warnings". Having done a "hard dump" yesterday (disconnected +ve lead for 20 mins), all the warnings continued, now with the addition of the parkbrake (it's the electric one) light flashing on and off most of the time when I took it out for a run. No evidence of binding brakes/discs being hot when I checked.

[J44EAG]

Despite the hard dumps and the problem persisting AND the electronic brake issue, I`d certainly be looking at a new battery. I can`t recommend the Bosch Silver and Varta equivalent batteries highly enough. Only when I`ve used that premium type battery have I ever had a problem free car! The cheapo batteries or old tired batteries cause just this sort of issue. I have an elderly battery here which is OK for summer use but it fails to perform in the winter. Low temperatures do not help.

You can leave the battery disconnected but obviously you have no in car security operating with that action having been taken. The car will have to learn the gearbox adaptive again for your driving style when you re-connect again. Thats no big issue.

Look for Bosch or Varta batteries of at least 90ah. (I remember that the battery size was an 069, but do please check. You can get these Bosch batteries of this size with 100ah capacity in the same sized case. That is very useful)

Hope that helps,

Mike K

[classicmorrisman]

That's most helpful - thank you very much, Mike.

Best wishes,

John

[fitman207]

Thanks very much guys for your much valued contribution. I will drop-test the battery and think about getting a Bosch one.

Kind Regards - fitman207

[J44EAG]

Not always appreciated is that not all makes of battery are created equal. Cheap batteries in my experience don`t always perform that well off the shelf. They just don`t appear to have a stable enough battery platform to perform well enough for our seemingly very sensitive cars.

So I suppose the best advice I can offer is to buy premium level batteries. Then you know you have the best and the most stable you can find. That gives a bullet proof point from which to start diagnostics for any issue that may still be present on the car.

One of those issues can be sorting out the electronic hand brake after a brake pad change. With my old, age unknown battery, I experienced difficulties after putting in a new set of electronic EPB pads. My XJR has a separate rear caliper just for the park brake. I was present at Jagcare in Portsmouth when the new pads were fitted and was fortunate enough to be allowed into the workshop as the work was being carried out.

To begin, we held the brake switch down with the ignition on. Still holding the switch down, we switched the ignition off. Moving to the rear of the car, we punched out the two pad pins on each handbrake caliper. Out came the old pads and shims. Removal of the caliper was required to wind the pistons back into each caliper to gain the space for the new pads. With new pads fitted, the anti-squeal shims and the pins were re-fitted. The essential thing was then to manually work the lever arms to push the pistons back out again to ensure the pads gained the correct working clearance against the discs. This must be done manually rather than using the hand-brake motor to do that action. If that mistake occurs, then the electric motor over runs its stops and that is irreversible. You then need a complete new handbrake motor unit to correct the problem!

We then moved back to the switch and ignition. Switching on the ignition, we pushed the switch down, then up a few times. On came the brake warning message and MIL lamp. Vile language ensued! We connected the garage SDD/IDS computer to the car and tried to cancel the faulting issues. No go. We tried my iCarsoft 930i unit and then my Android phone app and ELM327 unit. Still no clearance. Near desperation ensued and we disconnected the battery to hard dump computer errors and rigged up the garage mains charger to the battery for half an hour.

Half an hour later, we re-connected the battery after a charge and it was all systems go again! Not seen the issue again although I had planned to change the battery after the EPB problem. That battery got heaved out after I then experienced two other problems. On a cold day, I could start up first thing in the morning and the petrol cap would open and the glove box drop down. This was seriously annoying. I immediately replaced the old battery with a Varta Blue premium unit of 100ah rating. The result is that all those maddening issues are currently a thing of the past.

I`ll add that I could not economically operate any Jaguar without having one of the two diagnostic units present in the car at all times. Indeed I run the car with the ELM327 Bluetooth chip permanently plugged into the OBD11 socket on the car. If an electronic glitch ever occurs when out on the road, all I need to do is pull over and open the Torque Pro app on my Android phone. A few moments spent diagnosing and clearing codes at the side of the road clears issues and off I go again even if only just to get me home. No trips to the garage at huge cost and I have control of the situation at all times. The other day, I had been quietly driving around the country lanes bring my Father back from hospital. My car is supercharged and I run a water/methanol system on the car for extra performance. It was a cold day and the car was not fully hot. I pulled out onto a fast moving A-road, gave the car a significant boot of supercharged boost and a good squirt of water/methanol which I had set to begin to inject at 6psi above normal atmospheric pressure. On came the engine check light. Annoying but of no consequence for that short trip. At home, I found a P0430 code present which implied my sports cats had not performed well and caused the 430 problem. Google lead me to a Youtube video. The guy knew his stuff. Damp in the cats can cause 430 to be generated. It all added up. A cold engine and cats and a great gulp of water/methanol quenched what little heat was in the cats and caused the 430 code. Clearance of the code switched off the check light and off I went again!

Batteries, fault codes, MIL lamps, message centre legends and check lights are all part of the necessary electronic management systems and once understood make running a Jaguar a less fraught experience. Out of all of those potential issues, the battery remains the most obvious and common fail point and can generate a whole pile of odd and frightening codes. Replacing the battery in so many cases just makes issues disappear.

That`s my few pennyworth drawn from mucking about with these cars for over 20% of my life years to date!

Mike K

[classicmorrisman]

Many thanks, Mike - some very helpful and in-depth observations there!

John