I have a 05 6.0 l with 96K miles. When pulling a trailer, after I stop and refuel, I will sometimes get a wrench light and limp mode. It will reset by shutting off the truck and turning back on. IT does seem to be better if I let the truck idle for a few minutes before I shut it down to fuel up. It seems to happen more if I do not have the truck in tow mode, but it will happen in tow mode as well. I have a scan gauge II and I get no codes. The EOT and FWT are not to far off not anymore than normal which is 10-13 deg and occasionally it will go more than 15 deg for short periods. That causes no issues. I am not loosing coolant, boiling the coolant, or see any issues with the coolant. I am thinking it has something to do with the EGR or the turbo. Boost seems fine from the Scan Gauge. The EGR fluctuates ALOT with little to no throttle adjustment. It is not Transmission temp as that is also good on the Scan gauge. What else should I be watching? Any suggestions or thoughts?
Thanks,

 

On my truck, I do not see over 10 degrees delta and it is more like 6-8 normally.

Why are you so sure that it isn't the ECT/EOT? 15 degrees is the limit under certain predefined load situations (as monitored by the PCM). If it isn't the delta, then you are very close.

Do you have a boost gauge? Do you monitor system voltages? These can throw a wrench light also. The dealership should be able to call up a code on it if you should choose to go that route.

 

It could also be the accelerator peddle .

 

I see deltas of more than 15 at times and it does not trip a light. When the light trips, the EOT and FWT are under 15 deg difference. I can monitor volts, which volts are you thinking, FICM voltage, battery voltage? What would be normal? I could see how the FICM voltage could trip a wrench, but not a battery. I have a scan gauge II hooked up and running while this happens and I have the gauge on boost, EOT, FWT and TFT. Any other things to watch for? I can almost make it happen at will once I have the truck pulling for a while. It does seem to trip when I get on the throttle to climb a hill get up to speed, pass etc. It seems if I can keep the boost down, I can keep the wrench off.

 

Well, I am just telling you what Ford says:

The wrench light for a ECT/EOT differential is not just at 15 degrees - it depends on engine load also.

Also, the wrench light is thrown at low system voltage:

Store code and wrench warning lamp illuminated when PCM vehicle power (VPWR) parameter identifier (PIDS) is below 10.25V for 60 seconds or below 9V for 4 seconds. TSB 09-24-3

believe what you want ........

 

I know that is fords doc, but I have seen it up to 18 deg for a short time, and no light. And, when the wrench light occurs, they are within 15 deg, so that is my reason for thinking that isn't it. That was my original thought and the reason behind getting the scan gauge II. Maybe that's it. Are there codes that get stored that a Scan Gauge II can't read?
Thanks,

 

Scangauge is a great gauge, but a not so good code reader. Take it to your local dealer and see what the code is. For an hours worth of labor your guess work will be done. Sure sounds like its your oil and coolant spread as bismic said.After reading your second post it may also be a boost problem. How high is your boost when pulling a hill?.im not 100% sure but i think there should be a stored code when the wrench light comes on, and scangauge wont read it.

 

Boost seems to get to about 21-23 when I am on it hard. Other than that, it stays fairly low.
I know I need to do the Oil cooler replacement soon, and will do the EGR delete when I am in there. I think on the 05 I can delete it and not get a code.
Thanks,

 

Wrong...on an 05 with EGR delete you WILL get a code.

Depending on if you got the newest flash or not if you will get a wrench lite with the + 15* delta. With the original flash of an 05, you will not get a wrench lite when the delta is greater than 15*. Don't ask how I know!

 

Good info on the EGR delete. Thanks, I got a new FICM in September with the latest flash. I never had this prior to that.
I pulled 7 hrs yesterday with a trailer and here is what I know:
I got one wrench when the oil was it's hottest, probably 232.
As long as the oil temp stayed lower than 230. (I saw 228) The EOT and FWT can be more than 15 deg different. I saw as high as 18 deg diff and no wrench.

Based on this there must be a minimum EOT that allows the delta of 15 deg to trip the light. I am guessing it is 230 deg and be more than 15 deg then the wrench happens.
But I do know on my flash, it is not a straight 15 deg delta. Generally my truck running 70mph with a trailer in 90 deg heat and the AC on will run EOT of 220-224 with some spikes on the hills, FWT 210-212. If I ease up on the speed on the hills, I can keep the EOT under 230 and I get no wrench. If I leave the Cruise control on, I will get the light.
Also, another thing I have found. If I leave the truck idling while I fuel up, the EOT and FWT drop. If I shut it off, the EOT will actually get hotter quicker when I get rolling down the road again.
Based on all the info I now have, I think it is the Oil Cooler. But, I think knowing now that it has something to do with the actual EOT and not just the spread, I can nurse it along for a while since I am not loosing coolant. I will order a kit and plan for a long weekend under the hood. I figure While I've got it apart, it would be the right time to clean the EGR and the Turbo. And, I'm putting on a coolant filter. Ford should be paying all of us owners over this issue, or fixing it for us.

 

Mark, It also depends on which flash he has. Unless it's the last update the 05 didn't come with the delta spread defuel program.

 

Also, another thing, This ONLY occurs when pulling a two or three horse trailer with a load of horses. Driving down the road in just the truck, I am easily withing the 15 deg spread.

 

Your EOT's towing is pretty high compaired to mine towing my 30' fiver. I rarely have seen temps over 215. I did have the oil and egr coolers replaced and had studs in at that time too. But even BEFORE the oil cooler clogged, I never saw temps as high as yours.