2003 S-Type 3.0L V6 148,000 miles
VIN M68444

The solutions to these fault seems to be all over the place so I'm trying to pin down with my particular symptoms

When I start the car from cold I can run for a significant time at speed and touch the brakes on the highway, etc. and everything is perfect. After driving for awhile, when the engine is warm (not hot, just mid range on the temp gauge) these faults come on plus the DSC, ABS, Brake and engine lights. If I shut the car off for about 15 seconds and get going fairly quickly and up to speed, the faults/lights don't come back on until I have to stop and the engine goes to idle again. If I'm in traffic and can't get up to speed, the faults/lights come on pretty quickly.

I'm also occasionally getting a "restricted performance" warning that limits rpm to less than 3000 but this clears by itself after I drive about a minute and goes away and I can drive it as fast as I want.

Even with all these faults/lights I get 30+ miles per gallon at 70 to 75 mph and 32+ at 60 to 65 mph. on the interstate and I want to get this sorted so my wife won't get nervous driving the car.

So it seems the faults/lights only come on when I'm at low rpm. I have a new battery (and just had it checked again and its good) I had them (Advance Auto) check the alternator and it checked good too.

I'm thinking that maybe the Alternator is putting out some "noise" or a little glitch when its idling and that is causing the problem.

Has anybody else had these symptoms? ie get the faults/codes at low rpm?


Any help wojuld be greatly appreciated. I don't want to get rid of this car as the milage is great but my wife is getting nervous. I've had this car since it hat 30,000 miles on it and I am very pleased, just want to get this figured out.

Thanks in advance

 

Clarification of this paragraph

When I start the car from cold I can run for a significant time at speed and touch the brakes on the highway, etc. and everything is perfect. After driving for awhile when I slow down and the engine comes to a idle, when the engine is warm (not hot, just mid range on the temp gauge) these faults come on plus the DSC, ABS, Brake and engine lights. If I shut the car off for about 15 seconds and get going fairly quickly and up to speed, the faults/lights don't come back on until I have to stop and the engine goes to idle again. If I'm in traffic and can't get up to speed, the faults/lights come on pretty quickly.

I'm also occasionally getting a "restricted performance" warning that limits rpm to less than 3000 but this clears by itself after I drive about a minute and goes away and I can drive it as fast as I want.

Even with all these faults/lights I get 30+ miles per gallon at 70 to 75 mph and 32+ at 60 to 65 mph. on the interstate and I want to get this sorted so my wife won't get nervous driving the car.

So it seems the faults/lights only come on when I'm at low rpm. I have a new battery (and just had it checked again and its good) I had them (Advance Auto) check the alternator and it checked good too.

I'm thinking that maybe the Alternator is putting out some "noise" or a little glitch when its idling and that is causing the problem.

Has anybody else had these symptoms? ie get the faults/codes at low rpm?


Any help wojuld be greatly appreciated. I don't want to get rid of this car as the milage is great but my wife is getting nervous. I've had this car since it hat 30,000 miles on it and I am very pleased, just want to get this figured out.

Thanks in advance[/quote]

 

Smokey, so you have a new battery? Cause I was going to suggest a weak battery. Though others will be here soon to help you address the issues, I have a simple suggestion; after being sure that all fuses and connectors are snug, including the new battery's terminals on its posts, and chassis grounds are in place and tight; perform a hard re-set of the ECU (disconnect both battery terminals, touch them together for 30 seconds then replace). Our Jags have a funky electrical system that can be re-set by a "hard re-set".

 

bump

 

Did you try the suggestion & what's happened since?

It's not in my opinion the thing to do. Instead get ALL the codes read from ALL the related modules and get a detailed printout to post here.

My money would NOT be on a glitch, though it's a possibility. Could just about be a slipping drive belt or any of many other problems including a failing battery or bad connection.

Battery is #1 suspect by a mile. Read the forum and see..........

 

I found the problem with "restricted performance" which turned out to be a vacuum leak at a connector right at the throttle body. That has been fixed and I have not had the restricted performance since. I think that was unrelated to the other lights. Even with the vacuum leak I was getting 30+ on the highway - go figure.

I have not had all the module codes read yet so I still at the point where all the symptoms in that regard are as related before. I'm pretty sure the battery is good. It is new and a heavy duty battery that I've had checked on the "computer" twice and it always says its good.

Its the coming on when hot and only when I am at idle that has me stumped. That would seem to indicate something to do with charging or the alternator, etc. I was thinking about the slipping belt as when its hot and the lights are on the power steering seems "heavy" too but you'd think a slipping belt would make some noise. I can't recall the last time I replaced the serpentine belt so that tells me it wouldn't be a bad idea to replace it anyway. I'll also check all the connectors, grounds etc. and go from there. If anyone has any other ideas I'm open to suggestions.

 

Well done finding that leak!

The car will have learned (wrongly) how to do fuelling based on that leak
So, clear out its learning - disconnect the battery for a while (5 mins). That may fix the problem. It'll run a bit rough as it re-learns but should improve with varied driving. Fuller details are in the code (DTC) PDF in the FAQs.

There is a scale on my car and I think yours to show when the belt needs replacing but if yours may be original and at that mileage I'd just replace it. The tensioner rotates (against a spring) to loosen the belt and you can then slip it off. Watch your fingers!

Sounds like it's not the battery, so could be bad power/ground. Have you checked everywhere in the trunk (esp. under tire) for damp.water? Common problem