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Switched power


yetchh

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Hi, here's one for the sparkies (or anyone else) when wiring up my link I had a switched 12v right by where I was mounting it, all good.. But then when I try to turn the car off it keeps running till I either disconnect the relay or tap it. So I think it's the relay and get progressively bigger till I'm at a 70amp relay thinking that there's too much draw with the pump, coil, injectors and ecu on the circuit but no even that does it, I discover that there's 6v even when I turn the key off. Before I start the car it switches 12v on and off no problems. I go looking for another switchable power source only to discover that every switchable 12v source does the same thing.. Am I doing something wrong here? Do I need an inline resistor out something when switching a relay to ground? Got me stumped 

Cheers for any help, Thomas. 

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2 hours ago, ThePog said:

Some relays are latching, check you have the right type?

 

Yeah bro, I did think that but it works fine on and off with the ign without starting the car, it's only after I start and run it that it stays on. 

Edit*... Def not a latching relay. 

 

2 hours ago, ajg193 said:

If the car originally had a fuel cut solenoid on the carburettor you could use that as a switched 12 V source in the engine bay.

 

Probably not a very helpful response though..

 

I've tried them all.. coil, fuel pump, mains, everything that is switched. Same result.. Highly annoying upside-down in the foot well. 

 

1 hour ago, cletus said:

Might be barking up the wrong tree as I am the opposite of an electrical whiz

But I have heard of this being an issue with some alternators backfeeding other circuits so the car keeps running even with ignition turned off  

 

I did wonder if it could be something to do with the alternator perhaps leaking slightly but like you my sparkie skills are rudimentary, I get lost pretty quick. 

 

 

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need to find what ever is connected to the ign on that is causing the issue.  easiest way would be just start unplugging stuff, alternator, light bulbs etc  and puling fuses. till it drops the relay out. then go from there. 
or there is something janky with the key setup.

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13 hours ago, yetchh said:

I'll try some stuff tomorrow and come back.. 

From Link help file copy/paste:

"A large number of technical inquiries are received regarding problems due to incorrect wiring of auxiliary outputs. Incorrect wiring of solenoids and relays to auxiliary outputs can result in the following symptoms:
· ECU not powering down when the key is turned off.
· Accessories such as engine fans coming on when the key is turned off.
· Repeated clicking of relays when the key is turned off (machine gun sound!).
· ECU draining the battery over a few days.

The root cause of these problems is the wiring of hot fed (direct from the battery positive terminal) or ACC fed (key in accessory position) solenoids or relays to ECU auxiliary outputs.

Each auxiliary output basically consists of a low side driver and flywheeling diode. A low side driver is a power transistor that can switch a load to ground. Flywheeling diodes are required for the driving of fast switching devices such as ISC solenoids and VVT solenoids. Flywheeling diodes are also essential for reducing radio interference noise.

Unfortunately, the placement of flywheeling diodes means that if power is applied to auxiliary outputs through a solenoid or relay when the ECU is powered down current will flow through the flywheeling diode causing the ECU to power back up.

As solenoids have some resistance, the current that flows back into the ECU (back feeds) is not usually enough to power the ECU up properly resulting in the ECU powering up and down continuously. This causes unusual behavior by the offending solenoid and possibly other solenoids as its current is switched on and off."

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Its basicly saying that everything that the ecu supplies a ground too. Isc, boost solenoid, injectors etc...   needs to have its 12v+  supply come from relay  of which its coil is switched with ign on

If you have powered something directly from the battery or accessory its going to cause  issues

Sounds like you have everything on the efi setup running off same relay?  Its good practice to  use seperate relays and fuses for ecu, fuel pump etc.   And big current draw stuff 

 

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Ecu, coils and injection runs off one relay, fuel pump on its own. Main relay feed runs to fuse box with all the fuses of which the fuel pump also take power from.. So I guess in that sense evening does run off the main relay

Main relay is switched from ign not acc.. 

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