2004 XKR. I am occasionally getting alternating "Check Rear Lights" and "Cruise Unavailable" messages. This seems to be a failing Brake Light Switch, and I have one on order. Today at 70 mph with no messages displayed I got, for the first time, a "Restricted Performance" message. This was followed a few minutes later by the alternating "Check Rear Lights" and "Cruise Unavailable" messages. I was 100 miles from home, so I couldn't pull any codes. After shutting down the engine and restarting about 2 hours later, there were no messages displayed. Could this Restricted Performance message be caused by the faulty Brake Light Switch? Is Restricted Performance the same as Limp Mode or Fail Safe Mode?

 

You are correct that "Check Rear Lights" and "Cruise Unavailable" point to a faulty brake pedal switch at least 95% of the time. And I certainly wouldn't rule out a "Restricted Performance" condition being thrown into the mix as well. How old is your battery? And do you have any history of moisture getting into your throttle body?

Limp Mode and Restricted Performance are usually different animals with different causes....

 

Mine is a 1998 and when my brake switch went the only message I got was "Fail Safe Mode". The only noticeable difference was that cruise control didn't work, the car still drove with full power. Not sure if this is different on a 04.

 

The later the MY the more codes are stored.
Earlier cars have limited DTCs and the later cars have more diagnostic codes available to determine the cause of the fault.

I remember when you could 'short' 2 pins in the OBD port, get about a dozen 'flash codes' and THEN diagnose from there. We are getting spoiled and people still complain about the lack of information.

Soon all you will have to do is push a button and PAY a certain amount of money to get a 'DOWNLOAD' fix for the car???????

"ENTER PAYMENT METHOD AND DOWNLOAD NEW WATER PUMP AND COOLANT"!!!!!!!

Don't Laugh!! People thought the world was FLAT and horseless carriages were a FAD!

I'll be gone but transportation will not be.

bob gauff

 

Got a droid phone? Download the Torque Pro app (3.99 I think from app store) and get the ELM blue tooth adapter, then you can pull codes anytime anywhere.

 

We are brothers in misery - I had both of the same problems on my XKR recently.

+1 on the ELM and Torque. It will save you lots of hassles. If you don't have one, you can go down to Autozone and they will read out your codes for free.

In my case the restricted performance turned out to be an air leak but it could be any number of things so you need to pull the code to know. If yours is an air leak, read my other thread...

I am still puzzled by my own "Check Rear Lights"/"Cruise Unavailable". I found it's the 3rd trunk/boot lid light that's not coming on; I put a brick on the brake pedal and found 12v in the wire to the light so I assumed the light unit was faulty, I replaced it with another one and the problem persisted. What I've found is that the 3rd light comes on when the headlights are off, but does not come on when the headlights are on...? I can't figure that out.

 

The battery is 2 years old. The car has been garaged in the two years I have owned it and it hasn't been in the rain for at least 6 months. I hooked up the scanner and there were no codes stored.

 

Hi Tim - Don't have a Droid. I just looked on the Apple App Store and they have an app called OBD Fusion. I'll have to do some research and see what hardware I would need to go with it. Using something like this with my iPad sounds very handy compared to hauling around a laptop and a USB OBD connector.

 

Hello marcgr - I got out the scanner and there were no codes stored. Long Term fuel trims were high, so I might have a leak somewhere.

 

Hey PatB,
Did you have any luck with the OBD Fusion app ?

Thanks, Terry

 

Hi Terry - I went with the PLX Kiwi 2 Wifi OBD interface and the DashCmd app. I'm not real pleased with this combination because the app won't stay connected to the Kiwi. I bought an Autel scanner, I don't have the model number available right now, that I am very pleased with.

 

Pat I have the same combination and it works well. You have to turn off the auto detect IP and set the address. Then when you start the car just push the button on the Kiwi Box.

 

Thanks Rick. I'll try that.

 

Confirming - I also have a 98 and the same message!