Failsafe engine mode , ASC not available, Trac not available
 

New problem on my car, 2002 XJ8, even after cleaning all the connectors on the throttle body. I think is related to the gear selector cable adjustment, I did the mistake to take off the selector once without making signs on the cable threaded adjuster.
Today I adjusted it using some pictures where I could count the threads.
It starts OK, I can drive half mile without any problem, stopped the car.
Then, it starts, and few seconds after, Failsafe engine mode, ASC not available, Trac not available, the engine change it's tone,a little vibrating, rpm is increased, to 1200, and the pedal can push it only to 3000 in 10-20 seconds.
Last week I seen P0121 and it happened to have the engine stopped while I was driving. But one minute after, it started, without any problem.

Is it possible to be the bloody gear selector cable? All the positions of the shifter are recognized on the lighted part of the J gate.

Any advice?

What are the codes now?

Yes, I was thinking about that... when all the bad things happened... my ELM just decides to stop working yesterday, so no code for now.
It first happened about 3 weeks ago, after a guy plugged his tester (some profi equipment with a Panasonic laptop) to look for the coolant temp and seen just P1111 . Half hour later, I had the first problem ever with the engine stop and bad messages. Could be any connection?

Not sure but would like to see the codes. The P0121 is a plug connection code on the TB however, was it really P1121??? That is a TB problem!

Read this Link JagRepair.com - Jaguar Repair Information Resource

You need to get the codes before you make any assumptions. Document them correctly and post them.

Thank you, I seen already your recommendations two days ago, I cleaned all the connectors today and no change....
It was indeed P0121 , where can be other connections? I recently did some work under the dash, and an engine wash...with P0327 and P0332 for the knock sensors. But they were cleaned after.

Excessive water on this engine is not good and a good indicator is that you knock sensors were affected by the water or the cleaner. My best guess is that you have moisture in one of the plugs or in the TB controls I would suggest you put the car in a dry covered spot, open the hood and let it dry before you begin troubleshooting.

Just measured the knocksensor, on the connector near the cooling tower, it's 196 Kohms the left and 194 Kohms the right. Sounds familiar?

I removed the shifter cable from the J gate and moved the gearbox arm under the car to N,as in the JTIS, to be sure no missadjustment of the linkage cable is involved.

When it's cold it works OK, when it warms up, it starts throwing the codes on the screen, with the rev 1000-1200-1000 rpm(after I give some gas).

Update:
Looking under the bonnet today, I seen that the part load breather hose have 2 little holes, where it rubbed on the wipers motor housing. Evrika! some sealant and some tape and let's go!


I raced it about 2 miles, everything perfect, started the engine 10 times, in the garage,out of the garage, on the street,perfect!
When I was ready to go home, for a 10 miles drive, the same thing happened...bloody car!

At least now I can focus on the engine bay, no problem with the shifter cable and adjustment.

Can these symptoms be due of a leak in the breather system?

i am still thinking about TB...How common is a faulty throtle body on a 2002-2003 xj8?

check your breather tube repair again ... it might have gone bad again.

If you touched any wiring connectors while doing the repair ... suspect those connectors. Maybe they made contact after moving and have gone back to no contact.

I had the same problem with my car. The garage kept seeing codes for all sorts of things, but it wasn't until they had the diagnostic machine hooked up when it faulted that they spotted the usual "throttle body fault"

Check the plugs on the throttle body, and make sure that it's seating tight, and that none of the clips are broken or cracked.
I think the clips on my main plug had broken, and the fix was to wrap a cable tie around it to secure it. It seemed to do the job, as it has only faulted once in the last six months.

It's not an idea solution though. I might have to do some more research into possible throttle body upgrades. I'm sure I saw something somewhere about a larger throttle body being used with the Kenne Bell SC upgrade

Thank you for your help!
Today I removed the plastic covers from the engine, exactly like it was when the engine worked. I connected the battery,engine started, and D engaged.... for the next 10 miles, I drove it old style, no pedal to the metal, just a maximum 80 mph (in some states probably I would go to jail for this...:icon_slapcry:).
A few miles in the town, no problem... Left the car for half hour, and started again. No problem, another 1-2 miles. It was the most boring drive on my Jag, but happy for no codes.
I just ordered a new scanner Autel MD702 , let's see tomorrow how it's with the codes (the check engine light is still on).

I still think that the engine covers are pressing on the plastic breather hoses, and maybe they are moving allowing vacuum to escape.

Is it possible that a vacuum leak to cause these codes?

In the evening, when the car was resting, I tried it again; it started OK, trying the gears, all was sweet, then trying to give some more revs when in N, the messages comes again and that ugly voice of the engine killed me.

A few days ago, I noticed that one relay from the trunk fuse-box got hot, it's the one pointed here (the one at the base of the T) , any idea what is it for? I have a scheme but only 6 brown relays are there.

your picture is not showing

Ok, the picture can be seen now.

Just received the Autel today, plugged in immediately, only codes P1000, system check not complete, P1260 security input , and P0121 TPS circuit range / performance TPS1 compared to TPS2 .

Cleared the codes, drove the car, old style, no problem!

In the afternoon, after opening the bonnet (one cable just jumped from the latch, one more job for today...) I had a look under the spark plugs cover, remembering that yesterday when I started the engine , my father told me one plug is not firing.
The left cover was full of water drops, like after a rainy day, and some bolts were rusted.
Cleaned all the parts, taking out the coils, electric connector cleaner everywhere all back together.

I have all the reasons to think that my problems were caused first by the vacuum leak from the breather hose and secondly because of the water in the coils cover. When the engine was cold, the water was on the cover, when it was hot, it was vapors everywhere, causing misfiring.
But, no codes to see, probably only throttle body was shown.

Drove the car after, no problems, full throttle, it was OK, but still not enough power when floored it.
Is it normal after hard reset, to have a limited engine performance (without codes,of course) just till the ECU learn all the parameters again, for 20-30 miles?

It's happening again...

Apart from those existing messages today I got Gearbox fault, Low brake fluid, Engine stalled, plus the codes C1155, P1796, P1638, P1642, P0121 andD P1000.

The codes were cleared, and only Restricted performance was showen plus MIL on.

Cleaned the codes again, no codes, normal driving...

What should I search for.... brake switch?

This becomes my diary,... today I changed 2 wires from the TPS connector from the right of the car and from the pedal position sensor connector from the left.
Some description of this P0121 is that the signals of the two sensors are not equal.
Worked nice after, racing a little, left the car for one hour, and...you're right, it did it again....P0121 on the scanner.

If somebody can translate for me what are the connectors and pins recommended in the repair steps for this code, as I don't know who is who...

PINPOINT TEST D : DTC P0121, P0122, P0123; THROTTLE POSITION (TP) SENSOR RANGE/PERFORMANCE, HIGH/LOW VOLTAGE
TEST CONDITIONS
DETAILS/RESULTS/ACTIONS
D1: CHECK THE TP SENSOR SENSE CIRCUIT FOR HIGH RESISTANCE
1 Disconnect the battery negative terminal.
2 Disconnect the ECM electrical connector, EM11.
3 Disconnect the TP sensor electrical connector, PI06.
4 Measure the resistance between EM11, pin 11 (U) and PI06, pin 03 (U).
Is the resistance greater than 5 ohms?

Yes
REPAIR the high resistance circuit. For additional information, refer to the wiring diagrams.
CLEAR the DTC. TEST the system for normal operation.

No
GO to D2.


D2: CHECK THE TP SENSOR SENSE CIRCUIT FOR SHORT TO HIGH VOLTAGE
1 Reconnect the battery negative terminal.
2 Turn the ignition switch to the ON position.
3 Measure the voltage between PI06, pin 03 (U) and GROUND.
Is the voltage greater than 5 volts?
Yes
REPAIR the short circuit. For additional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.

No
GO to D3.

D3: CHECK THE TP SENSOR SENSE CIRCUIT FOR SHORT TO GROUND
1 Turn the ignition switch to the OFF position.
2 Measure the resistance between PI06, pin 03 (U) and GROUND.
Is the resistance less than 10,000 ohms?

Yes
REPAIR the short circuit. For additional information, refer to the wiring diagrams. CLEAR the DTC.
TEST the system for normal operation.

No
INSTALL a new TP sensor.
REFER to Throttle Position (TP) Sensor in this section.
CLEAR the DTC. TEST the system for normal operation



So, which are the E11 and PI06 , pins 03 and 11? How the hell, after measuring the pins on the harness, they recommend to change the TPS as being faulty?

Anybody was lucky enough to locate a seller for the sensor for an easy replacement? They just don't recommend "install a new throttle body", isn't it?

My VIN is out of the numbers recommended for the golden tips connector upgrade, they are already gold on both sides.

Recently I experienced similar problems to the same model car. The trottle position sensor TPS ssenses the position of the butterfly plate that controls the air intake. If the plate is blocked, even by a tiny amount, it sends a signal to the computer that there is an imbalance between the fuel and the air intake.
Over time a coating of carbon black builds at the plate. this stops the plate closing properly and causes a problem. If you disconnect the air tubing on the filter side of the air intake, to the throttle body and look into the body itself, operate the spring loaded plate by hand, gently, do not let the plate slam closed. looking in you will see the black carbon blocking the plate from closing. A Carb or/and throttle body cleaner can be sprayed in to remove the carbon and allow the plate to move through the whole range. I removed the throttle body housing from the intake manifold to prevent the fluid going into the engine but really that is not necessary the engine will burn it anyway. Let me know if this helped.

Thank you,if you suggest cleaning the butterfly valve as recommended here on the forum also, I did it with the ignition on, and pedal pressed, the valve is then wide open.

Use this link from my page JagRepair.com - Jaguar Repair Information Resource the plug that is in question is in the last two photos it goes to the throttle position sensor. Also in the comments I put a link to the TSB for the contact problem; however, it addresses MY 1999 to 2001 and not you’re my 2002. This is not to say the contacts are not the same or your problem but it would suggest you might have a position sensor problem and not a plug problem. If that is the case then you may need to have the TB rebuilt and this link might help JagRepair.com - Jaguar Repair Information Resource it also has a link to ASI who did the rebuild for me.

The connector and pin layout for the ECM is laid out in the earliest sections of the electrical diagrams. For other connectors, the location of the connect and type of connector is laid out in the notes page associated with each section of the electrical diagrams.

There should be a link to the diagrams in the stickies at the top of the section.

If you have JTIS, you also have the electrical diagrams. It is one of the other buttons at the top of the screen in JTIS.