I posted this in the "drivetrain" forum on 1/15 and got no replies. It's still driving me nuts so I'll give it a try here.

3 times now my truck has thrown a "P0118 Engine Coolant Temperature Sensor High" code. Trouble is in 2 cases the truck isn't even close to operating temp (just a few minutes after a cold start) and once I'd just been putting around town and know it wasn't too hot. The first time it happened, my Quad Commander readings on all metrics were freaked out and the factory gauge was pegged. The subsequent times I don't remember the Commander freaking out but the factory gauge was pegged.

The first time, I was rolling down the road (after about 2 minutes from a cold start) and the CEL came on. I stopped, shut it off, and it wouldn't restart immediately. I assume the ECM thought it was too hot. The last two times, the truck wouldn't start after sitting for a few minutes. It eventually restarts after a few attempts, so far.

Also, the ABS light has come on a couple of times since this problem started.

Since the Commander splices into the temp sensor wire I disconnected that wire this morning. That was more desperation than anything.

Since I posted this, it's happened twice more. Once on 1/20 with the Commander temp sensor plugged in then last night with the sensor unplugged. That's the first time it's ever happened with the sensor unplugged. On 1/20, no dash lights came on. Last night, the Brake and ABS lights were on for a few minutes after the truck finally restarted.

This is driving me crazy! Anybody have any ideas?

 

Did you check your coolant level?

I know its a long shot but some trucks wont start if the coolant is too low. Not that the truck is hot, just if the coolant is low. This is the case on some big trucks but I dont know about pick ups.

I know its not much help but I hope you get it figured out.

 

Thanks, wap, but the coolant level is about 2" below "FULL", well above the "ADD" line.

 

Check the radiator not the resevoir. If you have an issue always check the radiatior because you may not be sucking fluid out of the resevoir.

 

Just checked...the rad is full.

 

Not that it is common but, we had a guy in LA have a bad water temp sensor. Something internally was shorted and depending on the vibrations of the engine the sensor would work or not work. It was sort of weird and that is the only thing I have ever seen that is close to being what you described?

 

At this point I'll try about anything. Thanks.

 

Okay, here's an update. On February 3rd, I installed a new coolant temp sensor and I had no problem until yesterday afternoon. Again, as is typical, I'd driven the truck some around town, then, after sitting a while, it wouldn't start. No codes, no flaky gauge activity at all this time. After several attempts to start, I thought, "what the heck", and drained the fuel filter can, cycled the key several times, and it fired up like nothing was ever wrong.

So what's going on here? Is it "losing prime" (just something bantered around the office - I have no idea if that even exists)? Do I have a fuel pump issue?

One more thing...I'm thinking this started since I changed my fuel filter the last time. Did I screw something up?

Thanks guys.

 

It happened again last night, 2/21. I changed the fuel filter and it fired right up. Okay... Then this morning, again it wouldn't start. After several attempts, and a call to the boss saying I'd be late it finally fired up. Since the frequency is getting closer and closer, I decided to bite the bullet an drive it to the dealer.

The tech couldn't find any codes and the fuel pressure(s?) showed okay via the diag port. He found a TSB, number 18-003-06 REV. A dated September 27, 2006 and applied the current ECM level (he said my truck was down 2 levels). The text of the TSB says:

"The vehicle operator may experience extended engine crank time in cold ambient
temperatures on vehicle equipped with manual transmissions.

This Flash also provides the following enhancements:

* Improved Automatic Transmission shifting
* Engine fan is activated if the coolant temperature sensor fails
* Enhanced battery charging"

My truck is an automatic, so I don't know how hopeful I am. But, we talked about "long" cranking times and said up to 20 seconds won't hurt anything. Obviously, something is wrong if it takes that long to start, but 20 seconds won't hurt anything. I've been stopping in probably 5 seconds because it normally starts near instantly. We also talked about my Quad box. He said it would be no problem to warranty things like fuel pumps, etc., but if I, for example, cracked an injector, he'd play he** getting DC to warranty it with the fueling box. I said I totally understood that position and I knew what I was getting into. Oh, he also said he didn't think it could be causing the problem.

Anyway, that's the current status.

 

The last thing I wanted to do today was update this thread. Truck wouldn't start again last night. I finally bit the bullet and took my Quad Xzillraider out of the picture. It's been on the truck for over a year and a half so I just couldn't imagine that it was causing the problem. And why the heck didn't the truck throw a code?! The truck started instantly. Guess I'll leave it unhooked for a while and see how it acts.

Dang, shoulda had 'em enable the high-idle feature while I was there yesterday.

 

Tonight will have been a week with the Xzillaraider unhooked and I've no failures. I'm thinking I'll hook the wiring harness back up with the bypass plug installed. If I get no failure, then I'll hook the box back into the loop. Ideally, that will eliminate the failing component.

Since I'm not getting much participation in this thread lately, I guess my posts can be considered documentation for someone who might do a search later!

 

Keep posting, this will help someone out there. This is the kind of stuff that happens to me. I used to have a Buick Grand National that leaned to the drivers side. I had several different shops look at it, but NO ONE could correct it. I usually seem to have these types of thing happen to me. It's not nice that it's happening, but it is nice to know I'm not the only one having weird problems.

 

This morning the truck threw two codes:
P0118 Engine Coolant Temperature Sensor High
P0238 Turbocharger Boost Pressure Sensor High

Since my Commander taps both those sensors and my Xzillaraider is still unplugged, I think it might be time to call Quad about the Commander. Hope I don't have any starting issues today - rain and storms forecasted all day long.

 

I'd unplug the commander too...that way it will be easier to see where the gremlin is hiding. Sounds like you might have a couple of problems unrelated.ks

 

I agree. (BS added to circumvent 10 char min)