Evening Everyone!

A few weeks ago, in response the ENGINE IN FAIL SAFE MODE light coming on, I had the brake pedal switch(s) replaced. The harness it connects to was not replaced, the techs saying that the new switches came with an ability to connect to the old harness. That offered a few days of relief, but then the SAFE MODE light came back on. The light would go back out each time I shut off and restarted the car, then come back on after a few blocks of stop and go. (The only clue I have that the light is about to come on is that the cruise control will fail or not engage shortly before the FAIL SAFE light comes on.) So, the car's performance not being otherwise affected, I drove it around for a few weeks until yesterday, when the car needed a boost pak connected in order to crank and spark properly and it did finally start after great difficulty.

So today found it in the shop, where a new battery was installed and the SAFE MODE light/code history investigated and reset again with no problems found. They declined to replace the harness, even though I offered to let them do it. And of course the light came on again on the way home.

What should I do about this now?

 

Hi Skid,
Sorry to hear of the problem, do you have any codes? Just a stab in the dark you may want to look at the TB plugs http://www.gusglikas.com/AutoRepTB.htm Get the codes they should give you direction.

 

Thanks Gus. I hooked up the code reader and all it said was "5 codes: 1000, then the words: evap, misfire, fuel, O2 sensor" all on separate lines. No numbers came up for the words mentioned. Never seen it display that way, always had numerical codes along with words. Oh, well, I'll look into the TB plugs tommorrow. Thanks for the guidence.

 

My restricted performance was caused by a dirty MAFS. Code was a ' lean condition on 1 bank' . If I remember correctly it also affected my cruise control. I fixed it within 1 week of discovery.

 

I dropped the car off this afternoon at the indy shop I use so they could jump on it in the morning. I mentioned to have them check the plugs associated with the throttle body, to make sure the MAFS was cleaned, and mentioned all the codes I saw last night, including the O2 sensor, so we'll see what they come up with.

Thanks for the advice, and will report back.

 

Let us know what they come up with.

 

Sure will. Gus, do you think there's any point in replacing the brake switch harness while they're looking at the car today?

 

Let the shop look at it and see what they come up with.

 

The indy shop suggested that I take it to the dealer for a full scan, which revealed the brake pedal switch was still bad, so the indy shop has gotten another one which I will have replaced on Tues under warranty.

 

Chances of having your second switch fail is slim and none. Let that be a lesson for all of us. Find out if the switch or the install was the problem. I understand that the switch install is a bit difficult and could be related to it not working.

 

I agree, I almost fell down when they told me it was the same switch again. I'll ask about that when get it back next week. Another issue also came up, which is leaky valve cover gaskets on both sides. Should these have been replaced when the upper valve chains and tensioners were replaced? If they were, could they have been installed improperly? The bolts were checked and found to be torqued correctly. They leak on the exhaust manifolds at times too, smokes pretty good!

 

I never had the opportunity to replace the valve cover gaskets on either of my Jags yet but in my early years on other cars it was imperative that the surface be clean and dry on both the block and the valve cover. It was also important that the gaskets match the application, the surface of the cover be level and flat and last and most important that you do not over torque the bolts. The over torque will cause the cover to bend and bow creating the opportunity to leak.

 

Thanks Gus. It would be normal to replace the valve cover gaskets when replacing the valve chains/tensioners?

 

Yes it would have been, the question is did they?

 

I don't think so, but I''l ask.

 

Got the car back, Fail Safe mode has so far been avoided after a few trips that earlier would have set it off. Did get a restricted performance message on one, but it went out after about a minute. Nice to have one extinguish itself on it's own for a change.
The valve cover leak is very minimal according to the tech, and he did confirm replacing the old gaskets when the chains were done eight months ago. That's all the big items, perhaps now it'll behave for a while.

Now all it needs is a wash!

Thanks to everyone who advised me on this thread! It really helped!

 

Skid,
Was it the switch again?
This car loves to be driven, sitting will only give you more opportunities. Drive it and have fun.

 

Yes, the switch was replaced today, and the mechanic said that it "seated differently than the other one" when he installed it. Does it sound like we were sent the wrong switch last time?

I do drive the car every day. Bought it 4 years ago and have put 40,000 miles on it, lots of it highway.

 

Sealed differently that is a little strange. Where did it come from and did the new one come from the same place? And good to know that you are driving it. Now that we are retired we must change cars each day to give them equal driving time.

 

I'm having the same issue with a Failsafe Message.

I have pending codes p0173 ans p0175 telling me that the long term vs. short term fuel trim values are out of balance on both the left and right banks. It's true, I can see it on my scanner output. Basically, it's enriching both banks more than the EPA says it should.

Just last night I switched to a tank of Mid Grade from the usual diet of Premium. I think fuel quality might be the source of the codes.

Earlier this winter, I had the same codes come up about the time when we switched from "summer" to "winter" gasoline formulations here in Chicago. I was running Regular at that time. The fuel trim codes were current, not pending, and it would flip into (and out of) Restricted Performance mode. A switch to Premium cleared this up.

I checked the MAFS and ductwork and all that. I'm wondering oif the car isn't just particularly sensitive to fuel quality. I'm going back to the (recommended, I know) Premium and see if things clear up again.