Good morning, guys. I went to home depot with my XJR this morning. Car got to the engine safe mode/ACS/traction not available one time on highway and one time at red light,help help.

It's nice and dry today where I'm at and my XJR has the rebuilt abs module, new speed sensors.

Is the throttle body the top suspect? Nothing is more scary than losing the steering.

 

The TB could be the suspect for the safe mode. There are two sensors on the TB, the Pedal Position sensor (PPS) and the Throttle Position Sensor (TPS). The PPS is where the throttle cable hooks up and the TPS is on the the other side of the TB. These two units have to match up or you get the safe mode. I fixed mine by cleaning the PPS connector with some electrical cleaner and a little dielectric grease. I also had the "ABS/TRAC CONTROL" issue, but that didn't cause any safe mode issues, just the annoying lights flashing between the two. I replaced the ABS/TRAC Control module and all is fine, but I did clean the connector to the module using the same method as the PPS.

 

The sensors on the TB get dirty ... they use a duel track Denso sensors. With duel track any difference between the two paths in each sensor will cause problems.

The ABS module is not going to cause the failsafe -- only the track/abs

Any problem with the TB or CAN system will throw the ABS/Trac because they have to be working correctly for the cruise/ABS/Traction control.

The battery has to be in tip top shape. One of mine was going into fail safe -- often as I was coasting to a light or lightly accelerating (not always). Everything checked out ..but the battery was 3 years old. The car was stuck at my weekend place and since the battery is used in other cars I own -- bought a new battery vs having the car towed 100 miles. The new battery solved the issue and it's not come back -- over three years ago. The battery went into one of my MB and has been working fine. Same Bosch battery. I will note that the new battery did seem stronger at start.

The other thing I recommend is to cycle the TB by pushing the gas pedal to the floor .. I do both of mine a couple times a month for 50 cycles to make sure the contacts stay clean. My low mile 02 (I have two 02 R's) had an issue maybe 8 years ago with the FS .... and this solved the problem and it's never come back.

It's a shame Jaguar does not sell the sensors .. I was told many years ago that they needed to be calibrated in the TB. Even when Jaguar was replacing them in great numbers in the early 308's they did not fix -- it was the whole TB.

Good luck

 

Try and get a proper OBD scanner and read the codes. That will give a much better idea on what is wrong. The suggestion to check the battery is always a good one on these cars. Just like making sure all the electrical connection/grounds/fuses are clean.

There is one other well known problem that causes the engine to go into safe mode: The brake micro switch for the auto-cruise. There is a specific Jaguar TDC code if this is the problem. Replacing the brake switch is a simple job. But again, on these sort of problems best get the error codes, or you are likely to go into hit/miss mode.

Good luck

Jeroen

 

Hi guys.. I to have had these intermittent issues and replaced the 4 yr old battery and I thought that had fixed the FS mode, NO, it happened again yesterday. Swithc off, wait 2-3 mins and re-start, no problem.. frustrating.
Q. What is TB?

thanks!!

 

Short for throttle body