STA start relay feed to ECU

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Mat Grant

Member
Messages
153
Location
southern UK
Hi all,

Sorry to bombard the forum with wiring questions - but I've been going through my loom, figuring out what does what, against the lextreme diagram I've got, and the toyota diagram that I found somewhere.

My 1uz has the cold start injector, it is a 1992 soarer engine, with 40/40/40 plugs on the ECU.

I've been working through it and the last unknown connector is the STA - the docs I've got say "tells the ECU the engine is being cranked" and needs to be wired so that this pin on the ECU gets 12v when the engine is being cranked.

It is on plug E10 Pin 77 - labelled STA on the diagrams.

My question is this - from tracing the wire, it goes off into the loom, and in the part under the plenum, splices three ways

1 - to the cold start injector plug
2 - to the orange plug on a sensor on the coolant, this sensor is closed when cold
3 - to an in car plug.

Please can anyone explain what this is for? I'm guessing the start feed to the cold injector means it will fire when cranking, but if I have to feed the 12v off the start relay to this, what is the orange sensor for on the engine?

So should I just add the 12v from the start relay via the wire on the in car plug? And leave the rest as is?

Any help appreciated.

Thanks, Mat.
 
STA should receive 12V when cranking and only then.
Cutting the wire to STA has minimal impact if the engine is in good condition and is wired properly
 
Well I haven't personally seen that old engines (with cold start injector). But for those without one (I guess 1992 and up) , STA pin does very little to help with cold start.
 


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