defenderthom

Heres a copy of the Schematic that i have been working from. This is the info from the Defender workshop manual... 21 DESCRIPTION AND OPERATION RELAY - FUEL PUMP The fuel pump relay is located in the engine compartment fuse box/ It switches on the fuel pump to draw fuel from the tank to the electronic unit injectors (EUI). Input / Output The fuel pump relay is a 4 pin normally open relay. The fuel pump relay (C0730-4) is provided with a feed by the main relay (C0063-78) via header 291 on a brown/orange wire. An earth path is provided for the fuel pump relay (C0730-6) via the ECM (C658-5) on a blue /purple wire. This energises the fuel pump relay and allows a feed to be provided to the fuel pump. When the ECM interrupts the earth, the relay is de-energised and the fuel pump stops operating. The fuel pump relay can fail in one or more of the following ways: • Relay open circuit. • Short circuit to vehicle supply. • Short circuit to vehicle earth. • Broken relay return spring. In the event of a fuel pump relay failure any of the following symptoms may be observed: • Engine will crank but not start. • If the engine is running, it will stop. RELAY - MAIN The main relay is located in the engine compartment fuse box and Supplies battery voltage to the following: • The ECM. • The MAF sensor. • Fuel pump relay. Input / Output The main relay is a 4 pin normally open relay, which must be energised to provide a voltage to the ECM. The main relay (C0063-86) is provided with an earth path via a transistor within the ECM (C0658-21) on a blue/red wire. When the earth path is completed, the relay is energised and supplies the ECM (C0658-3, C0658-22 & C0658-27) with a feed on brown/orange wires via header 291. The main relay can fail in the following ways: • Relay open circuit. • Short circuit to vehicle supply. • Short circuit to vehicle earth. • Broken relay return spring. In the event of a main relay failure any of the following symptoms may be observed: • Engine will crank but not start. • If the engine is running, it will stop. For the ECM start up to take place the ignition feed when the switch is in position ’II’ must be greater than 6.0 volts.

Hi all, I have managed to get it started... BUT this was by removing the yellow Main Relay, and making a wire bridge between socket 30 into socket 87.... However I'm not convinced this is a safe or permanent solution. As the fuel pump is primed to run, as is all other appropriate relays... Fyi... When I make this bridge - and turn the ignition to start position... the temperature gauge appears to be normal, and the Engine Purrs! This then leads me to think that the blue and red wire coming out of black socket 21, on the ECU, is not providing any current to make the relay activate... Now should this cable be showing +12v when the ignition is on? or +(0) zero volts when ignition is on? I have run the voltmeter across the the two ends of the red and blue cable and it seems not to of broken anywhere. My understanding is that ECU socket 21 switches the Main relay, by providing a ground. Does this lack of relay activation mean that the resistor in the ECU has somehow become fried? therefore meaning I need a new ECU?? -( ££££ ouch!) Or what would happen if i were to cut that cable and permanently re-route the Red and Blue? Perhaps linking it to the ignition switch some how? I have checked the following. No Oil in the Red ECU connector socket. or on any of the cables in the seat compartment Some oil was in the outside of the harness connector under the main Cylinder head - Cleaned and tested circuit - all good no visible ingress into loom. I have run a Jump lead to the ground connector in the bottom of the fuse compartment, No Change, Checked the grey ground connector on the bulk head, all is good there. Checked the Blue connectors in under seat area - all good. ​No visible loose wires any where. Cleaned all connectors that I can find with WD40 Contact cleaner, including all in engine bay. Removed any auxiliary connections from accessories and extra lighting, Fuel pump is running fine when i bypass the Main relay. Thank you for your advice! can't wait to get the beast back on the road! Regards Defenderthom

Hi All! Thanks for the fast response. I'll head out and give all the different suggestions a try in the morning. Fingers crossed its not the new fuel pump route... if it is.... any suggestions re make? or best options - Should I cut a flap or Drop the tank? (loathed to do the latter as its a full tank, and don't have a ramp to hand... therefore lots of scrabbling on the floor!) Once again thanks for the sage advice. Will update everyone on what the solution turns out to be....

Hi All, Happily brought TD5 110 HT - 2005 - 10 months ago - And I am in Love! ( Esp given I live in 4x4 Heaven of Shropshire... and HAVE to use a certain CWMS Lane to go to the shops...(really I DO!) However- following the recent Snow and Ice when we had temperatures of -10,The battery was flat, and it refused to jump start, It would Crank over - But no compression was occuring - due to no fuel at ignition. Towed the Defender to a warmer spot - (Barn) fiddled with the relays, swapped them around etc. Checked all fuses - locked it - Unlocked etc. Wouldn't Start - It was Cranking over! but no fuel feed. Bled the fuel filter to make sure no water etc.. Now I put this down to Fuel Waxing having brought the Diesel in Devon (winterised vs non winterised fuel etc.) After much cussing, head scratching, I left it for the rest of the day. Then came back and opened it up, thought what the heck... give it one last go before calling the local stealers - Low and behold - the relays started to click, the fuel pump came into life and the mighty Td5 roared... Brilliant - didn't think any more of it. Until Today... Went to start the Defender having left it standing for a week - doors didn't respond to the fob... Dead Battery! Great! - realised it was the OEM Battery, so took the leap and brought a new 1000amp battery, thinking that will start a tractor... Brilliant... However - turned the key - NO Fuel pump whir... No fuel Pump Relay click, - Swapped relay for one i know to be working - (lights one) Fuel pump still not whiring- Checked Volts - all fine. - The Temperature needle is over at approx 80% just bordering the Danger-zone - This is strange given its 3 degrees out side and the engine is stone dead cold.... I'm loathed to pull the fuel pump out as the rear is boarded and carpeted - plus... Its the 110 HT - with Alloy floor covering the fuel pump - therefore have to cut thru the floor or drop the fuel tank? Does anybody have any suggestions> ? Could it be the immobiliser needs somehow resetting? due to a dead battery,? Is it an issue with the ECU not allowing fuel through because there is a fault with the temperature sensor? hence the dial showing a false reading...>?? Thank you for any help! Defenderthom.