Electronics won’t let me start my Z and OBD port and ECU won’t connect. Need a mechan

SteveSAS

Shouldn't have the fuse burnt before ground was lost?
Or is there a design issue? I haven't looked at these newer Nissan cars but the older ones with Hitachi electronics were very good.

2013-Z33

No, the failure mode starts when the ground level at the coil is about 2.5 volts or more above the ground at the ECU. Then the coil's driver turns on and drives the coil's primary to saturation. This becomes a static condition(ECU no longer has dwell control) and slowly overheats the coil module. At this point some of the drivers fail with the input shorted to the output(neg. side of coil). At no point has the peak current through the coil gone higher than normal, its just that its "ON" 100% of the time, that causes the thermal runaway.

SteveSAS

I need to look at what could have shorted out when belt grabbed throttle body cabling.

osburnrs

It grabbed the two wires going to the passenger side manifold intake control valve. It would still run at that point but the cel would stay on and when I disconnected the wiring harnesses is where all of my troubles began. I was checking the wires for continuity the key light and security lights came on and disabled the car from starting. Keys open and turn everything on and go all the way to start and engage clutch. When you push start everything just turns off but that was 2 ecu’s ago.




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2013-Z33

Those are the (CVTC) intake timing control valves. If the two wires that run to these were shorted together(one is +12v other goes to ECU) then when the engine is turning, the ECU's driver for them would get smoked as its trying to switch the battery to ground. As with the coil example the driver IC could get collateral damage. You said that the harness was repaired and the ECU was replaced after, if so then the next ECU should have been good to go...but if these two wires are still shorted together, each time the engine starts to turn you blow another ECU.

osburnrs

Correct on these. I don’t why I have trouble with the name. It’s not shorted and they function properly (you can hear them engage and I tested them before installing them) so like you, I thought fix and go and the car did. It wouldn’t let me clear the code and kept coming on and that’s when I started unplugging things and reconnecting to check for continuity and here I sit today with my own car that refuses to let me start it or steal it.


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SteveSAS

You do know that these CTVC servos have there own control module?
Sits near battery behind IPDM. I think the power electronics for these are in this module.
Sorry originally thought you were referring to intake control module as the throttle body control modules. Was a bit confused.

2013-Z33

No, they are not! The CVTC intake timing control solenoid valves that you have shown(mounted on the front of the front cover) are controlled from the (main) ECU, RHD(bank1) by pin 29 and LHD(bank2) by pin 18. The VVEL actuators(mounted on the rear of the cyl. heads) have servo motors that are run by the VVEL control module(mounted near battery). What exact DTC code were you getting after the damage?

SteveSAS

Sorry didn't look closely. Solenoid valves and not motor.
SM shows 7 ohm coils. See EC.pdf P0075 and P0081.

MarkL

Having same problem, I think: takes multiple presses of start button to start. Local dealer found clutch switches OK, then found a Nissan bulletin about the problem, which recommended reprogramming 'body control module.' That didn't work, so Nissan techs recommended replacing module. Quote is $1,200 (about half labor). Ouch!

bcfromfl

Z-cars have a couple of known issues starting, if you get no cranking at all when you push the Start button, just lights on the instrument panel. (And then have to cycle through several times to get it to "catch.") One may be the actual starter motor, but there is also a starter position sensor that might fail, or another sensor that the name escapes me at the moment.

There are several threads on this. I believe your issue is much simpler than what the OP describes.

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osburnrs

Mine has been at the stealership for a month now. They can’t figure it out either. It’s frying ECM’s still and I’ll post the solution if and when they find it.


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SonicVQ

As I see it, every wire from the engine to ECU/IPDEM-ER needs to be checked for shorts and opens. Yes, it will take a while. It might be easier to get a new harness from a scrap yard.

JARblue

lol paying $150 in diagnostic fees might be worth it just to watch the dealer fry a few ECUs

Good luck with your repairs. I'm with 2013 and Sonic... a different engine harness or an excessively meticulous check of the existing harness (can't just be visual).

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osburnrs

I had already changed the harness


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