We had a weird thing happen this morning - heading up the steep grade out of Panamint over to Death Valley in our 2018 TD6 with 25ft Airstream in tow. Gradually lost power and tge Rover switched into “reduced performance” mode and refused the hill. Not the most convenient location for that but we turned around and made it back out to civilization.

No other indications but seems likely something to do with trailer brakes - maybe one wheel binding was enough for the Rover to give up. Trailer brakes seem to be working on the flat (manual pull on the Tekonsha P3 controller slider stops andstarts the rig) although fairly jerky on slow speed braking now (was smooth before).

Heading to airstream dealer to get its brakes checked out now but was wondering if anyone else seen this shutdown mode before - perhaps the poor Rover was just too much overloaded. TD6 should be able to cope with most anything in 1st gear, right? I did not try low range - too worried about lack of cell coverage to play around out there …

 

For giggles, do a few vehicle tests:
1. Can you go up the hill without the trailer? Just see if the car does it again (I say this because if you can do the test in 30 minutes or so, then great test). Yeah go with just the car and see if it craps out again or struggles. That'll help you figure out if the car is ok or not.
2. Under the hood, check the intercooler hoses (or all hoses in general from the engine to the radiator area). What you are describing sounds like classic split intercooler hoses. Our cars are new enough that this shouldn't happen (but hey, here we are)

I think you are right to check the trailer. Go for another drive and then check wheel/hub temp. You should be able to put the back of your hand on the wheel/hub and it feel warm. If its hotter than that are super hot, then yeah trailer brakes are an issue. Also if possible, have someone drive the rover and go from like, 20mph to stop. You stand outside and observe what the rover is doing, what the hitch is doing, and what the trailer brakes are doing. The hitch will let you know if the trailer is braking more than the car, or less. You can also see if the brakes are locking up, etc.

 

Finger pointing back at the Rover now, or possibly the Tekonsha brake controller - had trailer brakes checked out by Airstream LV (shout out to Troy and his guys for getting us in and out with just time for dinner and a show :-)) and all in perfect order.

Maybe the brake controller was set up too sensitive? Now have it tuned it down to 7V instead of the default 14V that the Rover puts out. Maybe a steep hill causes the controller to trigger and apply brakes, even when you’re trying to pull a load up the hill? That would be lame. The Rover died on the steepest 10% section of the climb with, at most, 7300lb of trailer (likely less than that GVWR) which is well within LR specs. Am I expecting too much from a 3L diesel?

Anyhow, back on the road now - can’t go back to test without the trailer. Rover driving just fine on its own and with trailer on the level in 100+ deg heat. Onwards and upwards …

 

I'll actually come back on the rover as well.

This weekend a friend's F150 Ecoboost had a similar-ish task here in the southeast (1000ft to 2000ft, 96F outside, 70% humidity, hammering down, 8000lb load). Derated on a hill climb while towing. Engine temps went all the way up on it (engine coolant temp was 250F), but transmission temps were fine!!?? However a few weeks ago when ambient temp was 80F, no issues.

So I would say the engine was probably overloaded for an extended period of time and the computer derated to protect the car. Makes sense. In the past cars would just overheat and blow up when hammering down on hill climbs loaded. Now computers shut the whole thing down before hardware gets damaged. I know newer cars are better but machines still have limits. Just asking too much from the car

How were you driving it? Just in D and putting your foot into it? I'd say try sport mode and/or go to manual mode and choose 6th gear (6th would be 1:1 so no overdrive). You'll be going slowed but should keep the engine within its operating parameters. Best torque output for these engines is betweek 1700-2300rpm (I think, or about there). But yeah, sounds like engine just got overloaded and couldn't reject heat fast enough. Try taking it a bit easier, stay in the torque band.

So for manual mode, definitely play with it. In D and manual shift, it'll kick out of manual mode after a minute or so. I haven't messed with manual shift in sport mode though.

Give that a shot and see what happens.

 

I just had this happen to me this past weekend and I was curious about the brake controller. I also have a TD6 and everything was going great until I started a climb up a hill. I was in sport mode so I could shift w/ the paddles and have it stay in the gear I selected. The range rover went into limb mode and we luckily got to the top of the hill. I turned the car off and back on and the restricted performance indicator went out. We turned around and went back home w/ no issues. My temps never got high. There was no indication anything was going wrong.

Did you ever figure out what the cause was?

 

The engine puts our decent torque. Are you sure you need to tow in sport mode and paddle shift it down? Wonder if you were running hard in too low a gear? The auto box in normal mode should be perfectly able to change down if it needs to without intervention. Even if towing.

 

This was my 2nd time towing w/ the TD6 and I always give the car the benefit of the doubt and let it do it's own shifting. But when it's frequently bouncing between 6 & 7 or 7 & 8 then I take control and just select the lower gear and slow down a bit. I had thought maybe the sport mode could have been the issue.

I hooked the scanner up to it and there was an air intake code which seemed plausible. So I smoked tested the intake for 12mins and nothing let out the smoke. I looked inside the intake as much as I could and it's not all that gummed up for an 80k mile truck.

I am starting to wonder about the brake controller and/or the trailer. I never got out to see if any of the trailer brakes were hot to indicate they were dragging. But I thought the car would have pulled if they were or I'd see smoke from the trailer wheels. This weekend I'm going to do another test, have my scanner with me and pay attention to the trailer controller and brakes.

 

Our two shutdowns have both been on steep uphills, one going slowly (windy road, 10% gradient maybe), one at freeway speed. After the first one we smelled brakes on the up-slope: the Airstream Las Vegas mechanics checked out the trailer and found no issues there but they advised setting the brake countroller at something less agressive than the defaults and they helped me calibrate it on the flat. Didn't have any more problems then in a few thousand miles. But then the next season we got the 2nd shutdown - no brake smell this time so that most likely was just overloading the TD6 at the start of 3-week trip (3 people, full water tank, full liquor cabinet ...) and user-error in trying to go too fast. Again, no problems for the next few thousand miles after that. So I put it down to having to learn the equipment and work within its limitations. As I think I've posted elsewhere, I have procured an old F-350 7.3 diesel dually to try out on our next trip ....

 

Thanks for the info. We started out w/ the 7.3 excursion. Too few gears and the brakes weren't great. That was with a small 4k lbs trailer. Then we had a 3/4 ton chevy w/ the 6.2L gas and 6 speed. Much needed extra gears and the brakes were much better than the excursion. But then we got a bigger trailer, 6k lbs. The chevy couldn't do it so we put a supercharger on it, that didn't help at all unless it was below freezing out. The next tow rig was an eco boost expedition. Fastest towing vehicle we ever had, loved the tranny but it ran TOOOOO hot and the gas tank was too small for the horrible MPG. We had range anxiety every trip.

Next is the Q7 TDI. It's been the best tow vehicle to date. Huge brakes, 8 speed tranny, good MPG, and the air suspension is the star. Extremely stable towing. I feel the Land Rover TD6 should be comparable, maybe a little squishier w/ the suspension.

I hope I figure out the restricted performance issue. I'm going to hook up some thermo couplers to the drums and monitor the temps to see if there's an issue there.

Thanks for sharing your info.