Code reader plug

[SteveOS3]

I've been trying to get to the bottom of a sudden increase in fuel consumption, about 5 mpg less. I had the emissions tested and it's kicking out about 4x more than it should.

I checked and cleaned the air flow meters, they were pretty dirty, I haven't cleaned them in 8 years of ownership, but it made no difference.
Checked and cleaned the connectors on the engine temp sensor, no difference.

The boys in my local garage have lent me a old SnapOn code reader with a Ford 3 pin adaptor to try and get more info'. However, there are two plugs in my wiring loom;

The first photo shows the one that fits the SnapOn adaptor kit but it doesn't seem to communicate with the reader. The second photo doesn't fit any of the Ford adaptors. Can anyone confirm which is the correct plug?

Plug 1


Plug 2


Plug 1 is the only one that fits the SnapOn adaptor for a Ford 3pin but it doesn't communicate.

When we used a probe to test plug 1 we got the following reading:

Ignition off - all connections show Negative
Ignition on - Top pin negative bottom left negative bottom right no signal
Engine running - top pin oscilates live/negative bottom left negative bottom right no signal

Plug 2 reads negative in all three pins with ignition off and nothing in all pins when ignition is on and when engine running.


The wiring traces back to the ECU and all connections are in place there.

I'm going to replace the engine coolant temperature sensor as a matter of course but would appreciate knowing if I am using the correct tester jack plug.

Cheers,

Steve

Edited by SteveOS3 on Sunday 18th June 11:04

Edited by SteveOS3 on Sunday 18th June 11:08

[SteveOS3]

I've got that colour combination on plug 1, Ray

Just need to figure out why it isn't communicating.

Cheers.

[SteveOS3]

Ordered a Gunson 77032 earlier today and will look for any wires that need cutting on the octane sensor.

Many thanks for everyone's advice.

SteveO

[SteveOS3]

Link to the 77032 manual

Off to cut some wires.....

http://www.gunson.co.uk/items/pdf/Products/77032_I...

[SteveOS3]

Hmmm, took a look at the wiring on the octane connector and everything matches the wiring diagram below and the ECU connection numbers.

It's the Blue/Yellow wire that goes to earth on the diagram. Is this the one to be disconnected?



Cheers