My 2013 Jimny

I've just found the source of an annoying "knock" that happed randomly, never constant, smooth or rough roads may or may not generate the noise.
As Lambert said it was the exhaust, in my case the rear silencer box was hitting the towbar cross bar. 
Shaking the exhaust via the tail pipe DID NOT result in the noise, however a shake via the mid pipe and the knock was present. It was the second rubber support on the silencer stretching with age ( furthest away from tail pipe), in essence lowering it close to the crossbar resulting in a very random knock. 
Worth a check but you need to get under the car to shake the exhaust.
Good luckMike

@Lambert, @Scimike, thank you for the suggestions, I'll try to get under the car and check the exhaust this week.

Hi sergiu! I have the same problema you related above... "The next issue I had was related to the vacuum system and the 4WD controller, probably because I have a type 9 Jimny the 4WD controller was updated and expects input from the vacuum switch for both locking (closed circuit) and unlocking (open circuit), so shorting the switch would not work".

But in your case, you still have those pipes going to the hubs... but unfortunately I don't have that. Could you help me?

Thanks