Cant start car, ECM Relay not Engaging on its own, :/

[ali-d1936]

Finally went about tackling my no start issue with my S15 Spec-R, after fiddleing about for a while i Noticed the ECM relay (the brown relay located behind the ECU) was not Engaging on its own thus the coilpacks where not getting 12V.
I took the cover off clicked the Relay switch together with my hand and after a few attempts the car started :target:, so at first i though just a bad relay, took the Other brown relay for the Headlights out of the Fusebox under the bonnet, swapped them out but this one didn't click either, tested both for the Headlights and both worked, so this rules out a fault with the relay itself.
so now im wondering what causes the Relay to click over? this is taken from EC81 of the Service manual,

i have a multimeter, have checked values and they are all over the place, anyone know what voltage should be at what pin before i turn the key to crank the car? should they all read 12v? and should the Relay engage when the key is in the "on" position or the "start" position, i assume goign by the Diagram its "on" but just not sure

iv checked Fuses 34 and 35 and they are fine, iv checked both Earths and they are good also,
The Ignition switch pin at the ECU (pin 36) and it is getting 12V at the "on position"
Need some guidance on this hwell:

 

[Giop27]

If I'm reading it correctly pins 1 7 5 should all get 12V, at all times or with ignition on can't tell 100% as I'm used to seeing some note like hot at all times for permanent live but it shows a direct link to battery so I'll assume it's constant live.Looks like it switches earth inside ecu at pin 2 to actuallly move the relay over. Which would mean either ecu isn't giving the signal because it's dud or it's looking for another signal before it earths out pin 2 (hard to confirm without seeing where pins 6 and 3 run to off onto another page.)

 

[Giop27]

Oh and both earths may be ok but you could have a partial break/high resistance in any of the wires from the ecu going out the bottom of the diagram and the actual earthing point.

 

[ali-d1936]

Thanks giop, I checked for continuity with the multimeter on those two earth's today and they came back fine :-/

Where you mentioned pin 2 on the relay, it's connected to pin 4 on the ECU, reading up on it pin 4 is only used to "turn off" the relay, when the ignition is turned off 12v is sent back to #2 on the relay to disengage it,

I reckon you are right with the key in the "on" position pins 1, 7 & 5 should all have 12v problem is only 7 is getting 12v, so have I a problem along the fuse 33 line?
As soon as I clip the relay close every pin has 12v except for pin 2 (but this makes sense according to the manual as pin 4 on the ECU disengages the relay,

 

[ali-d1936]

Oh and pin6 on the relay runs 12v to the coilpacks

 

[Giop27]

Ok, try pulling fuse 33 check the connections of both the fuse and the wires it pushes into, assuming they are both ok I'd check continuity between the fuse 33 wires and the pin it should feed at relay. Either that or use a pin and wire to backprobe the relay with it connected to force a live in and see if the car starts.

Find it it a little strange pin 4 is for disengaging the relay though since the squiggly line inside the relay means it is the activating coil part of the relay which is for switching it on (and off I guess.) Makes more sense that pin 4 would be earthed by ecu when relay is required to be turned on, then 12v when ignition is turned off.

 

[ali-d1936]

i just thought id throw this up as its revelent, just about to go out and trace the 1 and 5 pins back and see where i end up

 

[ali-d1936]

Right just probed the relay with 12v from the ignition, when I hit the white and black wires on 1 and 5 the relay clicks to the on position, when I hit 12v off the red and black of pin 2 the relay clicks off again, so I'm going chasing 1 and 5 back to the fuse box and take it from there

 

[ali-d1936]

Found it, the F4 connector behind the ECU the pin for The wire was corroded and broken off, stripped back the wire and joined it bypassing the harness block and now for the first time in years the car starts thanks for all the help and advise giop

 

[Giop27]

Nice job mate, not sure I was much help hard with wiring when you can't stab wires yourself ��

 

[Connor]

I’m having the exact same problem not having power to pin 1,5 of my ecm, I’m also having a hard time finding fuse 33 you mentioned to trace the issue, can you point me in the right direction please