I haven't had my 1999 XJR for two weeks yet, and this morning was the first time it has rained since I bought the car. By the time I left for work, it was barely sprinkling and the roads were damp, but with no puddles.

When I started the car, idle was at 1100 RPM, which caused a transmission fault when I put it in gear. No worries, I just shut it off, restarted it, and waited 20 seconds or so for the idle to drop to normal. All was fine on the 3 mile drive to the gas station. I shut the car off and ran inside for a soda. When I returned to my car and restarted it, I had the transmission fault again. Once again, I shut it off and then restarted it. This time, the transmission fault warning went off again, but the performance was restricted. I couldn't get the engine to rev past 3500 RPM. I had no check engine light or "performance restricted" message. I drove it like this for 10 miles at 60 MPH, then stopped at another gas station. I shut the car off, restarted it, and it was fine the remaining 15 miles to work. I have no codes showing on my scan tool.

Any ideas?

 

Have your battery tested first.

 

I work at an auto parts store, and we have an excellent high-tech battery tester. I tested it last week, and it was perfect.

However, we did have a power outage last night, and I charged my cell phone in the car for half an hour (which means having the key turned to the first position to provide power to the outlet). I didn't even think about the fact that the battery could have been a little low this morning!

I'll test the battery again, and post the results in a few hours.

Owning a Jag is quite the adventure, isn't it? I've learned more about this car in the last two weeks than I've learned about every other car I've owned combined...

 

Okay, I found a moment to step out and test my battery. It looks good, but I did drive a total of 30 miles to work. Here are the readings:

12.51 volts
808 CCA (battery is rated at 850 CCA)

The battery is a Bosch brand, manufactured in October 2010, which means it was most likely put into use in late 2010 to early 2011, making it 2 1/2 years old (give or take a few months). I'll keep an eye on the battery a little closer.

Do you think owning a good battery tester is as important as owning a good scan tool? I'm starting to think so...

 

An adventure is an understatement! If the battery tested good and voltage is good then we need to move on. Take your OBDII code reader and plug it in prior to starting the car and drive the car stop and go. When the trouble comes up on the dash the code reader should capture it we hope. Document the codes and post them.

 

I'll see how it drives on my way home from work this evening. The car drove perfect for the last 15 miles of my drive this morning. It is very well possible that the battery was low and was then recharged by my driving. I will keep an eye on the battery, for sure.

I will plug in my scan tool before I start it, and see if anything comes up while driving. It is an Actron CP9575, and seems to connect to my car quite well. I'll keep this thread updated with any codes I may find.

Also, the car has always had a loud vacuum leak coming from the general vicinity of the throttle body. I have yet to determine the cause of the leak, but it is my understanding that it could be the cause of the occassional P0171 and P0174 codes that have popped up on my scan tool. Your thoughts on this?

 

Obviously any vacuum leak can cause fuel mixture codes. I have had intermittent problems on my XJ8 when the weather was damp, BUT they always had a Restricted Performance indication. It tuned out to be a cracked knock sensor. Have a look at pending codes, if you can.

 

In answer to the battery tester question... NO! Alll you need for a battery tester is to know the running voltage level, along with the "AC" componentof the running voltage. These cars are sensitive to voltage, but the batteries last a long time due to being large and trunk mounted. If you drive it regularly, you will have a problem every 7 or more years due to a worn out battery.

 

I've had the restricted performance message before, just not today. Today was the first time that the RPMs were limited, though. We'll see what codes, if any, pop up when I drive it home tonight. Hopefully, I just drained the battery some when I charged my phone last night...

 

I drive it 30 miles each way to work, for a total of 60 miles a day. No stop and go. All rural driving. I also usually make a separate 3 mile trip into town every other day or so. I'm hoping for a few more good years out of the battery.

 

Yeahm, but DO get that code reader! It will get used...

 

Drive it with the code reader installed until you get the restricted performance.

 

Will do. I will post the codes here as soon as they appear.

 

Well, it rained cats and dogs on my way home last night. I can safely say moisture is not the problem, as I could not get it to repeat yesterday morning's issues. I will continue to drive it with the scan tool plugged in, until I can get a "restricted performance" message.

I had no check engine light or messages, but I did pick up two codes with the scan tool. A P0400, and a P1000. How long after a reset before a P1000 changes back to a P1111?

 

Well, I finally got the car to recreate last week's incident. I got a P0705 code when the transmission fault message appeared. I shut the car off, then restarted it, and the message and code were gone. The car then limited my RPMs again, and would not downshift, but there were no messages or codes. After searching the forum for the P0705 code, I am fairly certain that my shifter cable needs adjusting. When I shift slowly into reverse, I notice that reverse actually engages when the shift lever is halfway between reverse and park. I'll dig into that next weekend, and we'll see if that does the trick.

 

Adjust the cable and see what takes place.


Transmission Range Sensor Circuit Malfunction (PRNDL Input)
What does this mean?
OBD Code P0705refers to
The park/neutral position (PNP) switch includes a transmission range switch. The transmission range switch detects the selector lever position when the shift lever is in the N or P shift position and sends a signal to the Transmission Control Module (TCM).
Symptoms
Possible sumptoms of OBD code P0705
- Engine Light ON (or Service Engine Soon Warning Light)
Causes
Possible causes of OBD code P0705
- Open or short park/neutral position switch circuit - Poor park/neutral position switch circuit connection - Misadjusted park/neutral position switch - Park/neutral position switch may be faulty The Error code is generally activated on detection of the following conditions: The transmission range switch detects the selector lever position and sends a signal to the TCM.

 

Update:

I didn't have time to mess with the shifter this weekend, due to an unexpected septic tank issue at home, so I have no update on that.

However, I did find that pesky vacuum leak. The plastic vacuum hose, that runs from the bottom of the throttle body to a valve of some sort on the firewall, had broken off at the throttle body. One piece of 3/8" fuel hose and 10 minutes later, it was fixed. I did it on my lunch break today. No more vacuum leak. The idle is much smoother, and I can't wait to see what my feline can do now!

 

After taking off the ski slope, I realized I didn't have the wrenches needed to adjust the shifter cable. I'll have to try again another day.

If I let the car warm up before shifting into reverse, I do not get the transmission fault warning, and I haven't had a restricted performance message since I fixed the vacuum leak, so I'll leave well enough alone for now.