Thread: Late puma with traction control - brake warning light comes on when descending

Found some more info:
While descending the brake light in the dash comes on intermittently, I read somewhere that the Puma actually has a type of a HDC but unlike in other vehicles that use ABS to slow the vehicle down, the ECU controls the engine speed, I have also read that if the ECU doesn’t do this the engine braking is so good due to the very low 1st gear that the vehicle would actually slide down the slope as if the brakes are being used incorrectly?

From here:https://www.google.com.au/url'sa=t&r...TnrNrSdRO8nNDw

Regards,
Tote

This is a good question , I also have a 2015 Defender . We that's my son and I noticed coming down steep hills in the Vic high country that was also in low range 1st and 2nd the engine behaved different , at times it even reved higher . My son is a Land Rover trained mechanic but no longer works on them . He was having a drive and noticed it first , he said look at this I don't like it . It was all good we were safe enough . I questioned Land Rover dealership about it , the guy there said they're suposed to do that ? I don't know have an open mind on this one ? Jim

My 2013 Defender doesn't have ABS/TC so cannot comment on that.

All the later model (TDCi) defenders have a feature called "idle jack". This feature is present regardless whether ABS/TC is fitted.

As has been mentioned LR engineers determined that in low first/reverse with engine at idle the wheels of a TDCi turn slower than is deemed optimal for safe descent on a steep hill. (A function of the low gearing, nothing to do with any electronic HDC action).

To correct this the TDCi ECU jacks up the engine idle speed by a few hundred RPM (from around 850 to ~1100 rpm) so long as ALL the following conditions are true:
- low range selected
- first OR reverse gear is selected
- clutch pedal position is close to fully up

The TDCi "idle jack" feature can catch you out if unaware how it works.

Imagine you want very careful controlled centimetre precise movement (forward or backward), there may be a small ledge or tree root at your wheel to overcome, and you are in low first/rev. As you carefully allow the clutch pedal off the floor and your vehicle is predictably taking up strain and maybe moving very slowly... comes a time the clutch pedal reaches the level where the ECU decides to ramp up the engine speed a few hundred RPM. It can cause you to lurch forward a bit more than you may have been expecting.

So so do remember it's there.

The experience that I had was at rpms that were higher than those that Idle jack would apply to. Without being able to gauge exactly I would say that I was at 1800-2000 rpm down a steep slope in low first on a closed throttle. My suspicion is that when I lost traction on a wheel and that wheel stopped rotating the engine management kicked in and fed fuel to the engine to prevent a stall. I'll do some further testing next time I'm off road. I like discovering (almost) undocumented features! For what its worth most of the documentation I can find refers to all puma vehicles so it may not just be the late ones.

Regards,
Tote

Originally Posted by tact

My 2013 Defender doesn't have ABS/TC so cannot comment on that.

I thought all 2007+ vehicles had TC and ABS. Is this not the case with some of them? Which ones?

Originally Posted by The Cone of Silence

I thought all 2007+ vehicles had TC and ABS. Is this not the case with some of them? Which ones?

(...mine was assembled in Malaysia. Doesn't have the same options available as Oz.)

TC and ABS was a $2500 option on my 130

Regards,
Tote