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R32 GTR Link Ecu disconnects while cranking


GodzillaMF

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Hello,

I have a issue with the ECU losing connection while it cranks. I have solved some of the issue with replacing the ign key cylinder to help with a 30 yr old. Key cylinder. I also read online that ground PIN16 helps keep the ECCS relay on and checking the voltage at PIN 45 I do have battery power. When viewing live cranking the ECU disconnects and then reconnects when it finally starts.  Would leave a temp ground on pin 16 by splicing in the wire to chassis? Or just direct relay power up a certain pin(s)? 

The whole engine harness is brand new. And reseated ecu connector to make sure the sides stay in. 

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Hello, AdamW what I'll do is make a jumper form pin 16. Do I completely remove pin 16 or just splice a wire onto it. I'm about to do so now. 

If it does stay on would be ok to stay a temp ground as I continue diagnosing  pins 45 and 49 etc?

Doing the jumper wire and will report in a few moments 

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1 hour ago, GodzillaMF said:

Do I completely remove pin 16 or just splice a wire onto it.

Either is fine, I would typically just poke a paperclip or similar in beside the wire so it touches the terminal.  

 

1 hour ago, GodzillaMF said:

If it does stay on would be ok to stay a temp ground as I continue diagnosing  pins 45 and 49 etc?

You only want pin 16 grounded when you want to run it, otherwise battery will go flat and you also wont be able to stop the engine once started.

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Pin 16 is controlled by a mosfet which is excited by pin 45.  The fact that it is dropping out when cranking suggests the voltage on pin 45 is dropping very low.  The mosfet should only dropout somewhere below around 7V.  So get a voltmeter on pin 45 and watch it when cranking.  A typical voltmeter doesnt update very fast so it wont catch a small drop but it will still be good to confirm voltage on that pin first.  If it is dropping below say 8.5V would would look closer at that circuit.  

If voltage looks good on pin 45 but it is still dropping out then there is a chance your ECU has a faulty mosfet.  We had a batch a couple of years ago that were out of tolerance and would drop out at a voltage higher than they should.  

 

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I'm in the process of removing a aftermarket car alarm starter interrupt relay that inline with the ign harness. But that starter interrupt is only armed when the car is locked as it should be.. but would it effect voltage to pin 45. Removing possible draw from ignition circuit. 

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Sorry the delay,

Tested pin 45 with key on, getting full battery voltage of 12.3 volts. Cranking to start pos. Voltage goes to lower then 10.0 volts. Measured at 9.998 volts until it recovers quickly to 10.8-11.3 volts with key in start pos.

 

Updating AdamW

The Gtr is on E85 with a Hellcat 525 pump on a fuel pump relay circuit (hot wire kit with relay) for it to help voltage load. The battery is the trunk and cable used is Welding wire gauge 0. Alternator is a Nissan Quest and the harness for that circuit is also new Wire Specialist along with the whole engine harness. 

The RB26 turns over but hate to have to see the Linkecu discconect while cranking. 

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AdamW,

Would running a Relay to ground pin 16 and and leave ECCS connect in the harness work. I think I may have one of the batches of Linkecu with a out of tolerance moseft as I read similar pages on the Link Support. Sending the ECU to NZ would be great and permanent fix?

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Yes, it sounds like you may have one with a bad fet, or possibly some damage from jump starting in the past or similar.  You can contact [email protected] if you wanted it fixed, it will likely be a warranty repair at no cost.  The other option as you suggest is to fit a new relay that is triggered by pin 45, and use its contacts to connect the wire from pin 16 to ground.  

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Adamw,

Let me do a 4 pin relay 

Relay: 85 to ground 

            86 (+) to pin 45 switched by ign

            30 to ground 

            87 (-) to pin 16 on the harness. 

 

Do I need to remove pin 16 from ECU harness and have it only connected to the Relay pin 87, or leave the wire connection on the connection to ecu and splice into it? 

Any other settings for Linkecu? I'll make sure hold ECU power is off. 

For the wire for pin 16 and 45 am I leaving them in or removing only 16 from the ECU harness? 

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