Mi16 Loom Relay Mystery.

[davemar 16]

I've got a Mi16 loom (for Motronic ML4.1) which I'm hoping to fit to my 205 soon. There's two relays on it, one for the fuel pump and the other seems to be for the ignition part of the circuit. The ignition relay seems rather weirdly connected to me. The coil part of the relay is connected to (what appears to be) a permanent +ve connection, and to a ground, so would be on all the time, even when the car is off. Surely this can't be correct, shouldn't it be connected to something like the switched +ve?

 

My 405 Haynes manual is a little inconclusive not having the ML4.1 diagram, so I can't see what exactly should be connected.

[GLPoomobile 958]

On mine, the injection relay (not ignition relay ) is connected as follows

 

Pin

1 - Goes to Pin 4 of the coil (this is essentially your switched live)

2 - Goes to the gearbox earth

3 - Goes to the shunt box (perm +VE)

5 - Goes to pin 35 of the ECU but also tees off along the way to the injectors and pin 1 of the fuel pump relay

 

You are right that it has permanent live from the shunt box, but the relay is open with the ignition off so there's no current flowing through it. When you turn on the ignition, the switched live supplies power to the coil, which in turn supplies power to the injection and fuel pump relays.

[davemar 16]

I think I've worked out what's going on, and I think my relay socket is incorrectly wired (unless the relay is non-standard, but looks normal to me).

 

This is what I seem to have:

Relay coil 1: Battery +ve

Relay coil 2: GND

Relay contact 1: Pin 35, injectors, etc.

Relay contact 2: Ignition pin 4.

 

So you can see why I called it the 'ignition relay' as it appears to switch the ignition coil on.

 

What I should have according to you and what also seems in the most appropriate of the Haynes' diagrams is this:

 

Relay coil 1: Ignition pin 4.

Relay coil 2: GND

Relay contact 1: Pin 35, injectors, etc.

Relay contact 2: Battery +ve

 

So it looks like one of the coil and contacts connections were swapped at some stage.

 

I am right in thinking that the relay connections are like this:

 

_ contact

 

| coil | coil

 

| contact

 

?

[Ryan 99]

Relays come with two slightly different pinouts - see the top of this page.

 

If someone has plugged in the wrong type then that might explain why your wiring isn't what it should be.

Edited December 13, 2011 by Ryan

[davemar 16]

Relays come with two slightly different pinouts - see the top of http://=http://www.vehicle-wiring-products.eu/VWP-onlinestore/relays/relays.php]this page.

 

If someone has plugged in the wrong type then that might explain why your wiring isn't what it should be.

Maybe they used the Type-A relay which makes sense for the pin-out I found. Haven't checked the relay used yet, as I can't find it after 'er indoors decided to 'tidy' up the garage! I think I'd prefer to stick to Type-B which seems more common and cheaper.