ECU - Fuel Pump Relay - Brown Wire Showing 12v?

[DanSE4]

Figured I try a post here to see if anyone can shed some light on the electrical issues I'm having with the V6 conversion in my SE4.

After literally hours of faffing around with meters, other test gear & diagrams from v6calibra.net, I've found one thing that seems totally wrong.

Pin 1 to the fuel pump relay (brown/blue switchable earth) goes to pin 46 of the ECU. Pin 46 of the ECU is the ground pulse trigger which should tell the fuel pump relay to give power to the fuel pump & then power to the ECU.

I have continuity between pin 1 fuel pump relay & pin 46 ECU but it's showing a constant 12v?

My mind say's that either the ECU is giving this 12v (that would be bad) or I have a short somewhere in the loom that's causing this. Either way, this wire seems to be the thing that's in the way of the car starting on the turn of the key.

It will start with a little "hotwiring", see below link.

http://www.youtube.com/watch?v=ICd8dNg1hQU

Any ideas or any tips on further trouble shooting would be most appreciated.

[Fraz]

oh you need a David for that one Dan....he should be along at some point think he is in Hong Kong or Singapore right now unfortunately


I remember we had a similar issue and it was one of the connectors up round the engine fuse box was not connected correctly, worth just going round and checking all your earths at the battery and all the wee connectors are right home

[RobbieV]

I said on one of your other threads on .com to connect everything up and then see what happens.

[v6 steve]

when i striped the Drain for respay it wouldnt start and we had to put a live feed to the fuel pump, so it could be moved about while it was painted, when i got the shell home (and it was only a shell with an engine) and started putting it back together it started working with out the live feed i had put on, now althought it was striped there was no wires disconected only windows and doors, it never made any sence to me but it might be the same for you, its a stad in the dark tho,

im sure David will have a good reason for you tho

[Calibra_Mike]

Have you tried replacing the relay? could be sticking or a bad contact...

[DanSE4]

I said on one of your other threads on .com to connect everything up and then see what happens.

Sorry mate, been so much going on with this sodding car that I haven't had a chance to respond to all the sugestions. Yup, I did that & nothing.

Have you tried replacing the relay? could be sticking or a bad contact...

The relay's fine (tried 2 now), it's the feed to pin 1 in the relay that should be a switchable earth but is showing as 12v live instead.

when i striped the Drain for respay it wouldnt start and we had to put a live feed to the fuel pump, so it could be moved about while it was painted, when i got the shell home (and it was only a shell with an engine) and started putting it back together it started working with out the live feed i had put on, now althought it was striped there was no wires disconected only windows and doors, it never made any sence to me but it might be the same for you, its a stad in the dark tho

A stab in the dark is always good mate but I've pretty much covered everything now.

It all seems that this 12v live at the relay that should be a switchable earth is all kinds of wrong!

[DanSE4]

I remember we had a similar issue and it was one of the connectors up round the engine fuse box was not connected correctly, worth just going round and checking all your earths at the battery and all the wee connectors are right home

I've been round the lot, several times over hoping to god to find something dodgy or badly connected.

Done all the earth connectors with emery paper, done everything they touch with emery paper, cleaned all the connectors with brake cleaner & once dry, connected back up with a good splash of duck oil!

This car is now the complete bain of my life! lol

[Fraz]

yes we did that as well then David came up and found one little connector that we had missed ...sometime just a fresh pair of eyes is needed

[DanSE4]

yes we did that as well then David came up and found one little connector that we had missed ...sometime just a fresh pair of eyes is needed

Road trip to Bedfordshire anyone? lol

[v6 steve]

Road trip we could pop in on Richard and have a look at this v6 at the same time

[rich30mex]

You are more than welcome to pop in at mine anytime boys lol

[DanSE4]

Right, some more head scratching & I think I have my head around this.

So, when I turn my key to 'ignition on' I should have 12v at pin 4 dis coil (which I don't).

In theory, I can then introduce 12v to that pin (for testing purposes) provided I don't disturb the fuel pump relay & ECU wiring to back feed anything.

If I do that & the engine starts on the key (the ECU has been powered, the fuel pump relay has also been powered by the correct path), I've found my break in the electrics?

[DanSE4]

Cheers, makes sense now.

Will get all that checked out & I'll let you know how I get on.

[DanSE4]

you are a star!

With ignition on, I get 12v from the plug at the back of the barrel (black wires) but it's not making it to pin 4 of the dis-coil or to the ECU. If I give 12v straight to pin 4 dis-coil from the battery (no other crazy wiring), the car starts on the key & does everything it should!

Just the hunt now to find where that circuit is being broken.

[DanSE4]

Will have a hunt, cheers.