D max can bus problems

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bva
Posts: 3
Joined: Fri Jun 07, 2024 2:24 am

D max can bus problems

Post by bva »

Hi
I have 2017 D max 1.9 tdi. It seems to have some can bus error. Sometimes all lights illuminate in the dash.
Check engine, abs, transmission light, immobiliser light and so on. This happens randomly and some times
transmission gets very harsh( new transmission ecu)...and it trows error in all systems, can bus communication error.
All can bus wires seems to be fine. Car only haves 64000km on it. I can not find similar problems on the internet.
Has anyone heard about problem like that....i am running out of options
mydmax
Posts: 2095
Joined: Sat Oct 12, 2013 8:36 pm

Re: D max can bus problems

Post by mydmax »

bva
I think you have a poor or dirty corroded connection to a vital earthing to negative point. For all systems to be indicating similar, they might be not getting a correct, TO NEGATIVE, connection.
A bloke I know had multiple sensor faults with his D40 Nissan. eventually trucked to local dealer and they confirmed it all. They, without knowing what they did, must have unbolted the SUS earthing lug to negative. they put it back together and miraculously it had NO SENSOR FAULTS at all. Of course, check all LOOM PLUG for integrity too.
Mike C
Posts: 144
Joined: Fri Dec 10, 2021 7:13 am

Re: D max can bus problems

Post by Mike C »

I've generally found random sensor failures to be due to poor electrical connectors or a bad battery. If you have a diagnostic tool that can read deeply into fault codes it will come up as "low sensor input voltage".
bva
Posts: 3
Joined: Fri Jun 07, 2024 2:24 am

Re: D max can bus problems

Post by bva »

Thanks for the reply. But the problem is that can bus voltage is dropping from 2.7 v to 0.2 v randomly.
It looks like that some thing is grounding can bus wire. All wires looking good. I think that i have faulty ecu...
Davros
Posts: 17
Joined: Sun Jun 02, 2024 8:58 pm

Re: D max can bus problems

Post by Davros »

bva wrote: Mon Jun 10, 2024 6:54 pm Thanks for the reply. But the problem is that can bus voltage is dropping from 2.7 v to 0.2 v randomly.
It looks like that some thing is grounding can bus wire. All wires looking good. I think that i have faulty ecu...
It may sound crazy but do you have rats around that may have chewed on some wires? Then the wires touch something?
Also, does it do it when it is cruising on a flat road or only over bumps etc.? That would likewise point to a damaged wire or plug.
Have you had anything installed like a CB radio, spotlights, trailer wiring etc., where a wire may have got pinched or broken? Or where they may have tapped into a circuit that has now been damaged?
bva
Posts: 3
Joined: Fri Jun 07, 2024 2:24 am

Re: D max can bus problems

Post by bva »

I have spend lot of time looking for damage in the wires but can not find anything. There is no auxilary stuff in the car, light, cb and etc.
This problem happens at random, some times driving or just idling after start. Has even happen when i switch the ignition on then i
notice the can bus voltage drop. Then maybe after 10 or 20 sec voltage goes to normal again just with the ignition on and engine not running...
mydmax
Posts: 2095
Joined: Sat Oct 12, 2013 8:36 pm

Re: D max can bus problems

Post by mydmax »

BVA
Just checking wires may not be the solution. To me, what you describe as happening at start,Key oN, or while driving is very indicative of dirty earthing lug eyelets screwed to chassis, as mentioned, re Nissan above.

Just because it LOOKS clean does NOT mean it is a firm connection to chassis/body. Some/most are not cleaned under the lug/eyelet and TOTALLY rely on the bolt to carry all required current flow to/from, because electrons run from NEG to POSITIVE.
Some I have discovered have the bolt firmly bolted and the bolt thread is ACTUALLY INSULATED from the body work by paint under the lug AND, MOST IMPORTANTLY the paint in the prior sprayed/dipped bodywork ensures NO DEFINITE CONNECTION between Lug and Bodywork. YES, The threaded bolt, screwed in and tight is being insulated by the paint in the thread.
I ALWAYS uses a 6mm tap, usually they are 6mm, to clean ALL paint from inside the thread and clean the area where the lug contacts the body. Sprayed with Lanolin spray also means any corrosion is largely prevented.
The current flow initially might be sort of ok but deteriorates over time with electrolysis/corrosion and problems begin. WORSE near the beach.

ANY lug can be detected as ok with a multimeter set on OHMS to read EXACTLY THE SAME as when the probes are touching each other, ANYTHING ELSE means a look see and clean etc.
That is what I would do first.
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