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TT Link - wont power on when hot, intermittent


headsock

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TTlink plug and play. Audi TT 225 1.8t

Runs and starts fine. After around 1 hr driving, it will randomly not start after shutting engine down. It runs and drives fine until engine is shutdown then ecu wont connect to laptop.

 

Ecu will not connect to laptop, tach wont sweep.

Let it cool down for around 10-30min, turn key on, tach will sweep, ecu will connect to laptop.

 

Tested power/ground wires

12v power on pin 3, 62 and 21 (21 is supposedly 12v feedback from a relay when not powered on)

Grounds on 1 and 2

 

Stock ecu will start engine even when Link wont start. Albeit with skewed afrs due to unplugges sensors.

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11 minutes ago, headsock said:

Tested power/ground wires

12v power on pin 3, 62 and 21 (21 is supposedly 12v feedback from a relay when not powered on)

Grounds on 1 and 2

Our ECU only needs 12V on pin 3 and one of those grounds to power up.  If you are positive that power and ground are present on those pins at the times when it doesnt power up then my only conclusion could be there is a hardware fault with the ECU and it will have to come back to us for inspection.

 

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Is there another way to check if ecu is powering on? Only way im checking it's powering on is by connecting the laptop.

 

As for power i tested it when it was acting up, by immediately removing the harness then use a multimeter to check if there's power on the pins then reinstall the harness and connect laptop. Didn't go as far as depinning it and checking the actual pins and harness.

 

Will shorted sensors/injectors/coils cause it to not power on?

 

For warranty do i send it thru the seller/retailer or directly to you? Purchased it in Usa. Whats the usual time frame to be expected, 1 month or more likely around 6?

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16 hours ago, headsock said:

Is there another way to check if ecu is powering on? Only way im checking it's powering on is by connecting the laptop.

If you open up the case there is an LED on the top board that will be lit up when the ECU is powered up but I dont know how practical that is with the TT ecu.  The tacho sweep is probably a reasonable indicator as you have already mentioned.

 

16 hours ago, headsock said:

As for power i tested it when it was acting up, by immediately removing the harness then use a multimeter to check if there's power on the pins then reinstall the harness and connect laptop.

I think you really need to back probe the wires somehow to test voltage with the ecu still attached rather than testing with the ecu unpluged.  Sometimes if there is a bad connection there is still enough current able to make it through to give you a decent reading on a volt meter but as soon as there is any load connected to the circuit (ecu plugged in) the voltage drops to nothing.  I dont know what the TT connectors look like but you can probably pull the covers off the back and poke a paperclip or pin down into the relevant terminal.

 

16 hours ago, headsock said:

Will shorted sensors/injectors/coils cause it to not power on?

Yes, that could potentially drop voltage enough to prevent power up.  This is is why we need to test voltage with ECU plugged in.

 

16 hours ago, headsock said:

For warranty do i send it thru the seller/retailer or directly to you? Purchased it in Usa. Whats the usual time frame to be expected, 1 month or more likely around 6?

It can come direct to us, there is information about how to return here: https://www.linkecu.com/contact/ecu-service-requests/   Typical turnaround is about a week provided we can reproduce the fault in testing easily. 

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Thanks for the info. Not sure if this will be easily reproduced out of the car. It 100 % always works when cold.

 

Can i wirein the 12v and ground directly to the battery. Worried i might have a poor ground somewhere and let it all pass thru the ecu. 

 

Will opening the case to check the led void the warranty?

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