Booked in my Defender TD5 90 (2001) for MOT today, and it wont start.
I am not the worlds best auto electrician.
When I switch on the ignition I dont get the yellow lights for plug heaters and cant hear the fuel pump.
Checked the relays 19 and 16 I have a live feed on pin 87 fuel pump relay
so I checked the pin 85 relay coil, with ignition on and off dont seem to have a feed.
using a bit of copper wire I jumped 87 to 30 fuel pump starts up
it looks like the relays are not having their coils powered.
Looking at the diagram the coils should be powered by a signal from the ECU I wonder if the power into the ECU could be the problem,
Would appreciate any help from an expert or someone who has seen this story before
I have attached the diagram I am using

The fuel pump relay and glow plug relays take 12v to the coil from the main relay (18 on your diagram). This is in turn controlled by the ECU on the ground side and the inertia switch on the 12v side. If the inertia switch detects a sharp acceleration (e.g. a crash) it will cut off the power to the main relay coil and kill the engine. So first check this (and the fuse (F5) which powers it) and push the button in.

The ECU switches the ground side of the circuit, so if it's not switching then pins 85 should be hanging at 12v with the ignition on, going to ground when the ECU output activates.

FlyingPete said:

The fuel pump relay and glow plug relays take 12v to the coil from the main relay (18 on your diagram). This is in turn controlled by the ECU on the ground side and the inertia switch on the 12v side. If the inertia switch detects a sharp acceleration (e.g. a crash) it will cut off the power to the main relay coil and kill the engine. So first check this (and the fuse (F5) which powers it) and push the button in.

The ECU switches the ground side of the circuit, so if it's not switching then pins 85 should be hanging at 12v with the ignition on, going to ground when the ECU output activates.

Click to expand...

Pete
Many thanks for your help.
I will make some checks with the fluke meter this morning, I will also plug in the nanocom and see of there are any faults logged and charge the battery up fully. I have an old ECU with an intermittent fault so I may put that in and see if the fuel pump and heaters pull in.

FlyingPete said:

The fuel pump relay and glow plug relays take 12v to the coil from the main relay (18 on your diagram). This is in turn controlled by the ECU on the ground side and the inertia switch on the 12v side. If the inertia switch detects a sharp acceleration (e.g. a crash) it will cut off the power to the main relay coil and kill the engine. So first check this (and the fuse (F5) which powers it) and push the button in.

The ECU switches the ground side of the circuit, so if it's not switching then pins 85 should be hanging at 12v with the ignition on, going to ground when the ECU output activates.

Click to expand...

GOT IT
Reading your post made me think its the feed to those relays.
I had taken out the Fuel pump relay and tried it, with a 12V supply to the coil, so I took out the main relay 18 it seemed to click with the 12V on the coil , but I know I had a couple of old ones somewhere, managed to find one and changed the main relay, imediatly "click" yellow heater plug light came on and fuel pump kicked in.
Bled the fuel system and it started up
Thanks for your help, put me on the right track.
Better order a brand new relay.

This time of year the cold can affect batteries - and if the voltage drops enough some relays won't work. It's worth checking that you are getting at least 12v before you start replacing things.

zeaphod said:

This time of year the cold can affect batteries - and if the voltage drops enough some relays won't work. It's worth checking that you are getting at least 12v before you start replacing things.

Click to expand...

Yes I wondered if the voltage may be an influence but a while ago I added a little extra (see picture) reads the system voltage. I checked it against my fluke meter and it's reasonably accurate, not bad for a cheap e bay special.