Thread: Puma Limp home. No Codes. Re-boot fixes

Later Defenders go into limp mode if you drive them a little harder when cold,and if you're going up a steep hill on the freeway and the temperature rises slightly. LR think of everything😁
If your thermostat is stuck open,not a good thing! Better get it fixed.

Originally Posted by Marty90

Later Defenders go into limp mode if you drive them a little harder when cold,and if you're going up a steep hill on the freeway and the temperature rises slightly. LR think of everything😁
If your thermostat is stuck open,not a good thing! Better get it fixed.

Thanks Marty
Unfortunately neither is a factor in my case...no hard running nor high temps.

My guess- Accelerator pedal position sensor (APP).
FSM says it's a dual rotary potentiometer- ie power (volts) goes in, less power comes out and goes to the ECU/ECM for makign things happen (simply put). Sounds like a dual redundant circuit, for safety etc. So probably 2 pins at the ECM (but I haven't looked over the wiring diagram).

FSM also mentions that if one input from the APP fails, then engine response is limited to the first 28% of pedal travel.
If both inputs fail, no bueno. Also mentions that you'll get a high idle, and idle drops to normal when brake pushed (so once you stopped, you'd probably not notice anything was amiss!).

For it to go FUBAR like it did- intermittantly- I'd probably trace the wiring to the APP, and From the APP to the ECM. Something it probably dicky.
Do the old wiggle the loom and try to force the problem trick. I reckon you'll have some luck. Obviously not while driving... but have it idling with handbrake on, and try to force the high idle symptom.

Brake pedal switch failure can also work with similar symptoms as the single pot track failure on the APP (28% pedal response)... so also keep that in mind.

Couldn't help myself... looked at the wiring diagram.

Power to the APP comes from the ECM and returns to the ECM via plug C0872 on the ECM (should be the middle big plug on the side of the ECM which is in engine bay, on the firewall behind the engine).
6 wires in total for the APP:
2x Black wires (ground)
1x Red/green trace wire- Pot track 1 power wire ('to' APP)
1x purple wire- Pot track 1 sense wire ('from' APP)
1x White/grey trace wire- Pot track 2 power wire ('to' APP)
1x white/greent race wire- Pot track 2 sense wire ('from' APP)

Experience with other cars is its often a 5V signal, and something less than 5 return, depending on the scale/resistance of the potentiometer.
If it is in fact anything to do with the APP, then its most likely wiring, possibly ECM intermittantly wigging out, and least likely a failure within the sensor.

Good luck.

In my research on my recent problems, I came across many references to a similar problem with older rangers and transits, go to accelerate, limp mode no fault codes.
End result was faulty temp sensor on fuel pump.
I know that LR do their own programming, but I'd put pound to a penny that they lay their stuff on top of the ford program.
If you get no joy elsewhere might be worth considering.

Cheers Glen

Thanks Glen and Mitch
Sorry for the lag in reply. Was out of the loop on the W/E. Electrical is one of my weaknesses, but I'll look forward to checking those out.
Cheers
Brid

Look into the SCV - sounds like it could well be your issue

Scv fault usually also gives a very poor idle and difficult starting.