2012 Navara D40 loss of 50% power only when towing

jaym · May 10, 2022

Hi all,
I have a 2012 auto trans D40. Runs absolutely perfectly when NOT towing. I don't get any warming lights on the dash or any unusual anything actually. There were no fault codes when we hooked it up to the testing unit.

We've had the car from new and was bought primarily to tow my wife's horse float.

Just in the last 2 weeks, as soon as we hook up the horse float with or without a horse onboard, it instantly becomes gutless. Feels like trying to tow 2.5tonne with a 1.3 litre Hyundai. But still no warning lights on the dash or any strange noises.

I've read that it may be the SCV but seems there are a whole bunch of varying opinions on it. I have also tried cleaning the injectors with an injector cleaning additive but it did nothing.

Anyone got any experience with this?

MANNING · May 10, 2022

Have you checked Brake light globes on either the Nav or the trailer?
How about the trailer plug? dirty or broken?
strange its just when hooked up

Old.Tony · May 10, 2022

^ Yeah makes me wonder too.

Why not just unplug the trailer and drive it around a bit and see what happens?

If that improves things, chances are you've got some power feeding into pin 2 of the socket (the third pin from the right in the socket that's mounted on the car, when viewed from behind the car). If you're not using reversing lights on the trailer, open the plug on the car and remove the wire connected to this pin (actually a socket on that side). That only removes the symptom affecting the car though, it doesn't fix the problem which may exist in the tail lights of the car or in the trailer - don't know without doing a thorough test of the circuits.

jaym · May 11, 2022

MANNING said:
Have you checked Brake light globes on either the Nav or the trailer?
How about the trailer plug? dirty or broken?
strange its just when hooked up

Hey, cannot thank you enough. It never occurred to me to try that and to my surprise, the problem is the horse float!!!!!

gazza414 · May 11, 2022

did you take the horse out

jaym · May 12, 2022

Old.Tony said:
^ Yeah makes me wonder too.

Why not just unplug the trailer and drive it around a bit and see what happens?

If that improves things, chances are you've got some power feeding into pin 2 of the socket (the third pin from the right in the socket that's mounted on the car, when viewed from behind the car). If you're not using reversing lights on the trailer, open the plug on the car and remove the wire connected to this pin (actually a socket on that side). That only removes the symptom affecting the car though, it doesn't fix the problem which may exist in the tail lights of the car or in the trailer - don't know without doing a thorough test of the circuits.

Hey, cannot thank you enough. It never occurred to me to try that and to my surprise, the problem is the horse float!!!!!

I will take your advice in regards to pin 2. We never tow anything other than the float which obviously doesn’t have reversing lights.

Thanks very very much!