OK let me try and explain this the easiest way I can. A (CAN)controller, area, network is series of small wireless routers that communicate with the many modules throughout the car.These little guys are placed over the car,and are receiving data usually from the connected modules via fiber optics.Now if one of these guy stop communicating then the CANBUS network will fail.It is a cool system,and usually is bulletproof.What is good about it,it kinda screens the errors before they go into the ecu so that the car wont shut down because your window wont go up or down etc.I am by no means a expect but just sharing with you my understanding as simple as I can make it...

 

Thanks 912 Guy. When I mentioned this to dealer, they said they can not pin point the fault because the codes are historical and nothing new. No new hard codes to pinpoint the throttle body or anything else. I don't understand this since I told them what message center read when the limp mode occurred. They still have my car. I am allowing techs to drive home in it. After a week, the limp mode has not re-occurred. I am thinking about picking car up this Thursday if they have not discovered problem by then. I am sure throttle body replacement is expensive. I used to work on my own cars back in the muscle car days. However, things have become complicated with computers controlling things. Is a throttle body something a shade tree mechanic can replace, or does it have to be calibrated or anything. In other words, can I do this without the high tech stuff the dealer has? Does computer have to be reprogramed after a repair like this? I am getting a little frustrated, but don't want to be in an accident on interstate if this limp mode occurs again. Is what they are telling me true about not being able to pinpoint yet? Do I need to take it somewhere else?

 

I will say, removing and replacing the throttle body is VERY simple.

VERY Simple
I have removed mine a few times to clean it, inspect in and whatnot. It literally takes like five minutes to remove.

Remember, do it as the engine is cool. There are two coolant lines that connect to it.

Other than that, four 8mm bolts, its off.

Also, pay attention to the two connectors on the throttle body. I.E. the Throttle body control and the TPS. Over time, the heat generated by the engine tends to make those plastic connectors very brittle. Use care while disconnecting.

 

The problem is going to be the TPS. Mine fails when the temperature outside hits 30 degrees. I tested this by driving 2,500 km in temperatures of 21 degrees. Got back to Joburg and as soon as we saw 30 degs it failed.
The TPS is not serviceable and the whole TB has to be replaced. I have searched the world for the TPS and althoug some Chinese companies claim to make them I have not had any joy in procuring.
Sorry to be the bringer of bad news but thats the way it is.

 

Yes thats true the throttle body is very simple to replace, it is plug and play.Just make sure you put the coolant lines back in place,these will run to the left side if your facing the throttle.Also do not disrupt the brakebooster line running inside the induction plate that the throttle body rest on with those 4 -8mm bolts.It will have one gasket beneath it that you will see.I recommend getting some electro-motive electical cleaner to clean the contacts ...it is made by crc(sold at any autoparts store),and it works wonders and I have seen this stuff bring a worn or calcified connector back to life.Even at times the smallest build up will make the tbs give the wrong signal.Just spray the pigtail and the male side also.If you have a air compressor apply air to it afterwards.We have used this on marker lights,knocks sensor pigtail harnesses,abs pulse sensors,and ballast harnesses also.It does work well,if the unit has not malfunctioned.Usually moisture will form corrosion on the connector and or people will rinse the motor and at times just plain old rain water can at times be the culprit.

 

Ok thank you all. Very helpful advice!

 

On the note about "plain old rain water", that is when my TPS seems to fault. When it is raining, has rained, or there is excess moisture.

Everytime my car faults, I clean the connector with connector cleaner. The problem goes away. For a few hundred miles.

 

Open the hood and spray LIGHTLY in the engine compartment near the TB and see what you come up with. Note Do not soak the engine compartment just a light spray. If water is a problem you need to find out why. Caution the knock sensors do not like to get wet.....

 

Usually it is the xjr that suffers from the rain water because the throttle body is near the firewall where the rain could interrupt the unit.The xj has the throttle body to the front above the plenum of the motor,but just like Gus said check all areas near the sensor for potential leaks etc