hotwire V8 wiring

Ralphh85 · Post by **Ralphh85** » Fri Apr 04, 2008 9:39 pm

can someone confirm that like the above sticky, this is the white for ignition, purple/white fuel pump output and brown positive?

this is an automatic and im not sure where the brown and orange wire is i need to ground?

help much appreciated!

Ralph

Post by **Coops** » Fri Apr 04, 2008 10:16 pm

are you 100% sure its hotwire before you get into the wiring?
and when i did my loom i untaped it all to remove redundant wiring,
and then found the wire that way, was a while ago now i did mine.

Post by **Coops** » Fri Apr 04, 2008 10:22 pm

right,
this loom in your above post mate,
is this in the Rangie that has a vacuum pipe missing?
if so its a flapper system NOT a hotwire set up mate,

Ralphh85 · Post by **Ralphh85** » Fri Apr 04, 2008 11:43 pm

it could be flapper, an yes it is same one as in the other vacume thread, i thought it was hotwire as its an '90 but thats not realy inportant,

so i dont have to worry about that wire if its a flapper?

Ralph

ChrisJC · Post by **ChrisJC** » Sat Apr 05, 2008 1:07 pm

White is ignition
Brown is +12
White / purple is fuel pump feed
White / red is cranking signal (it makes the fuel pump run whilst the engine is cranking)

Don't know about the others....? Never seen a flapper with so many wires!

Chris.

Ralphh85 · Post by **Ralphh85** » Sat Apr 05, 2008 7:33 pm

ChrisJC wrote:White is ignition
Brown is +12
White / purple is fuel pump feed
White / red is cranking signal (it makes the fuel pump run whilst the engine is cranking)

Don't know about the others....? Never seen a flapper with so many wires!

Chris.

well the others dont do anything anyway, nothing comes out of the connector on the other side so i will discard them from my loom.

next question, see pic....

here we have..

White (ignition)
Green/blue (water temp)
brown yellow (battery warning light)
white brown (oil presure low)

and what is white/grey?????

maybe something to do with rev counter? tho i expected rev counter to be white/black as thats what my car is?

and where can i get a rev counter feed from? as if i use the back of the coil its goign to double my revs cause my cars origonly is obviously 4 cylinder?

Ralph

edit, also is this the only other connector connecting the engine to the car? other than the starter motor wires and the ecu plug?

ChrisJC · Post by **ChrisJC** » Mon Apr 07, 2008 7:27 am

The ECU needs a feed from the ignition coil -ve to tell it that the engine is turning. It doesn't go through the other multiplug, so that might be your unknown wire.

Chris.

Ralphh85 · Post by **Ralphh85** » Mon Apr 07, 2008 8:07 am

i would thinkt he ecu will get the revs through its main harness which goes in to the engine loom,

it ust be for a rev copunter i think as this is the only other thign the car would need, according to mr multimeter its not connected in anyw ay to the coil?

where else could the engine get revs from? an injector maybe?

Ralph

ChrisJC · Post by **ChrisJC** » Mon Apr 07, 2008 12:40 pm

Ah yes, but don't forget that the EFi system is fuel only. The ignition is completely independent (distributor + coil). So you need to feed the coil -ve signal into the ECU loom (and on to the ECU) somewhere so that the ECU knows that the engine is turning.

And the rev counter gets its input from the coil -ve too.

Chris.

Ralphh85 · Post by **Ralphh85** » Tue Apr 08, 2008 8:09 am

pin 1 ont he ecu plug which i believe is the one which should go tot he negetive of the coil, and its white and black which backs it up doesnt seem to be conectted to anything, i have checked for resistance between it and earth, coil +ve and -ve, an few other bits and cant work it out, then even worse the fuel pump aint going and it wont start lol. its possmy bro dissconnected something ons at i didnt know about, but going back tonight to finish takign engine out and try an work it out.

does anyone know where the restister is located on the white/black pin 1 wire?

Ralph

ChrisJC · Post by **ChrisJC** » Tue Apr 08, 2008 9:16 am

The fuel pump will only run if:
1 - Engine is cranking (controlled by +12V on white/red)
2 - Engine running (controlled by flap in air flow meter being open).

So the best way to test fuel pump wiring is to turn on the ignition, then manually open the flap in the air flow meter. The pump should start up.

If it's a flapper from a Range Rover, the pin1 wire goes via some in-line resistor (lots of threads on whether you need it or not) to a relay. This relay has a white / blue wire which goes to the coil -ve. This is the overrun cutoff relay controlled by the overrun cutoff valve. The relay interrupts the signal when there's a high vacuum in the inlet manifold (so you get better fuel economy). So you need to check if you have this relay with the white / blue wire coming out , and whether it's connected.

Chris.

Ralphh85 · Post by **Ralphh85** » Tue Apr 08, 2008 10:42 am

great info will try just that in few hours, failign that i have probly dissconected an earth, or my ecu has broke, i paniced a bit abotu this as i have left it in direct sunlight in the back of my car for a day or 2, tho i didnt think this should be a prob?

if its debaitable weather you need the resister then if it dont work i will try directly linking the pin 1 white/black to the coil negetive and see if that helps.

cheers
Ralph