Scanner won't connect to ECU
 

Hiya new to this forum, so first up 'hello' to all. I hope to be able to contribute as well as quiz.

This one is the latter.

I have a 2011 370Z Roadster auto (32k miles) which recently went into 'limp'. Once switched off it would no longer start. I have two scanners, a wifi unit (Tacklife) attached to Torque Pro for Android and iCarsoft CR PLUS neither of which will talk to my ECU, both simply fail to acquire a connection over any of their pre-defined protocols.

I know that both scanners are working as they can connect happily to my other car.

Having disconnected the battery to try to 'reset' the ECU without success I called my breakdown provider (sorry, don't know what you call them in the U.S.) who was also unable to connect his scanner to the ECU. In the end I had the car recovered to my nearest Nissan High Performance dealer who told me that there was a problem with the battery. They replaced it, cleared the ECU and gave me the car back.

All was fine for about 200 miles and the exact same thing has happened again.

So, the first question to my learned peers on this forum: does anyone now of an ECU state where it simply fails or rejects connections?

Unfortunately I have not tried to connect to the ECU when the car is healthy so I don't know whether this car just won't talk to a non-Nissan authorised scanner or it won't talk because of this current problem...or, perhaps, because the ECU has been programmed to reject connections under certain conditions.

The car goes into Accessory mode fine, but when I try to start it or simply press START a second time, all dash lights come on, the engine cooling fan fires up and most of the dash warning lights illuminate. Very little works. I cannot even roll the windows up :mad:

Given that Nissan seemed to correct the problem temporarily with a new battery (which I have trickle charged to full) it seems logical that this is an electrical power problem, maybe not enough amps available to draw upon for ignition? However, I have tried a new, unused larger battery for my other car without success. This could, however, be because the ECU needs to be cleared which I cannot do.

For further consideration: About three days before the first incident, I accidentally left the lights on and flattened the battery. An embarrassing tale that I won't go in to :o My wife drove to where I was armed with jump leads and the car jumped fine. Could the jump have damaged something like the alternator perhaps? I have never heard of that myself, but it seems like it might be at least remotely possible.

Finally, if I have to have the car recovered back to Nissan again, does anyone know of a way to put the auto gearbox into neutral so I can roll it out of my garage? :confused:

Cheers all


P.S. Probably should mention that I am in the UK and it is a Zed manufactured for the UK domestic market

In the US, the 16pin OBD port started in the mid 90’s & by early to mid 2000 the same port was called (Global OBD connector); as they still were 16 pin connectors/ but the pin location was different & if the diagnostic tool wasn’t designed for global,,,they would not connect.
You can try checking your fuses that send power to the connector; as if one blows-it won’t connect.

https://uploads.tapatalk-cdn.com/201...76167a3175.png
Unsure what’s required in the UK, as countries differ all over the globe.


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First thing I'd do is check CAN fuse(s). See jchammond's comment above.

Then I'd make sure the battery is good.

I'd then try another ECM reset - disconnect the battery and then step on the brake pedal for a few seconds (the pedal turns on the brake lights which drains any built up charge).

If none of the above work, it may be a bad ECM.

Thanks for tech stuff to check. The better of the two scanners is iCarsoft CR Plus so will check the pinout and other suggestions.

Thanks a lot. I'll update when I have some success.

Apologies for the DOH! question about neutral

BTW: have it on fairly reliable sourcing that on most cars post 2000 the CAN is on the same power circuit as the in car power (lighter) sockets. I have tested them with a USB charger and they are working but of course, that doesn't help if the CAN is on a different circuit. I'll confirm that theory when I come to testing it.

This is true for GM but just because it's true for one manufacturer do not assume it's true for all. For example if memory serves me right VW/Audi actually put the fuse in the back of the radio itself (genius right). I forget how Acura has it but I do not believe they have it tied into the 12v accessory port either since it's common to blow that fuse.

...for interested parties, an update:-

Whilst in the process of removing the glove box to disconnect and extract the ECU to send for diagnosis and repair, I came across a YT vid showing how to reset the ECU of an Infiniti G series housing a VQ37ED. A carefully times series of actions on the start button and the accelerator pedal.

I tried it and the ECU really did reset and both my scanners were then able to connect. So the ECU was either in an error state where communications could not happen, or an error state had been thrown which instructed it not to communicate. I suspect and hope the former.

The only code in the ECU was a U0101 - Lost communication with TCM - Permanent.

I think this is a false negative thrown by a stuttering ECU which put the car into limp. Either way, it's cheaper and quicker to send the ECU off for a check than to diagnose loss of communication between TCM of an auto box and ECU for which the most common causes of the fault are broken wires, corroded wires, corroded fuse contacts, bad grounding and RODENTS!

BTW the sequence to reset the ECU from the drivers seat is (where each number is a one second verbal count i.e. "one-Mississippi, "two-Mississippi" or the UK version "one thousand, two-thousand" etc): -

Press START to Acc mode

count 1 second - Press START to ignition on (foot OFF the brake)

count 3 seconds - Fully depress and release the accelerator pedal five time in quick secession (under 5 seconds)

count 7 seconds - Fully depress and hold accelerator for 10 seconds

release and count 10 seconds

depress and hold 10 seconds

Release, count one second and press START to turn ignition off.
As long as this has been done to within time tolerances the ECU will reset (well mine did). There was no visible notification of success. The car started and I was now able to connect via ODB port. This is a 'harder' reset than disconnecting the battery.

This could be tested by forcing the ECU to throw an error - e.g. disconnect the MAF and start the car.

if shes an automatic and it persists check the connector on the trans (above the pan on the side. the clip can break and it can come loose. a gentle wiggle just to see if its still clipped is all, other than that scan it often like once day and see if you catch any pending codes.