Land Rover Discovery II Fuse Box Integrated Relay Repair

Land Rover Discovery II Fuse Box Integrated Relay Repair & Upgrade History: I recently experienced an issue where none of my door locks were responding to any electronic

un-lock un-lock commands. With the key I was able to unlock the driver’s door only. All locki ng commands worked normally. While troubleshooting troubleshoo ting the issue I could hear a relay click in the passenger compartment fuse box P/N YQE000251G (03’ ( 03’--04’) 04’) YQE000410G (99’ (99’--02’). 02’). After reading numerous online forums and reviewing RAVE it was the consensus that the only option was to replace the fuse box. This post in particular helped to confirm 2004-discovery-electronic-doorunlocking-doesnt-work . I verified that there were no super-locking or anti-theft issues. As an added note if you do super-lock the doors while experiencing experiencing a relay / fuse box failure you will not be able to unlock or open doors, as no electronic signal can be sent to reverse the super-lock motors. This will create a very frustrating situation as some reading up on o n super lock nightmares will illustrate. Not being entirely satisfied or convinced the only solution was the purchase of a new interior fuse box ($425.00) or to find a working salvage part with the gamble it would experience the same fate. I began to examine the RAVE electrical schematics schematics and dissect the fuse box looking for a solution. Symptoms: All door locks do not respond to command for unlock or lock from central lock in dash switch, exterior door key switch or remote key FOB. FOB. This issue will affect all locks simultaneously. simultaneously.

for the Land Rover Discovery II utilizes (3) NEC EN2Explanation: The electronic door lock system for B3N3ST integrated relays to control the lock / unlock function. The NEC EN2-B3N3ST relay is actually 2 relays in a single enclosure for a total of 6 relay controls. These relays are integrated into the Fuse Box circuit board and are non-serviceable. Failure of any of o f the 6 relays normally requires complete replacement of the passenger compartment fuse box. The NEC EN2-B3N3ST relay is a discontinued component. component. NEC no longer manufactures this component component and there is no cross referenced part available that is a direct replacement. Solution: My solution was to re-engineer the electronic circuit to utilize an exterior mounted and

serviceable relay to repair the internal fuse box and restore circuit functionality.

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Repair Procedure:

1. Disconnect vehicle battery and remove interior fuse box. Reference RAVE for detailed instructions. 2. Remove all fuses and relays from fuse box. 3. Carefully open the plastic clamshell clamshell enclosure to expose circuit board. Be careful not to break the clip tabs off as they will be required to hold the case closed after repair. I used round toothpicks and several flat blade screwdrivers to shim the tabs back as aids to open. 4. Remove circuit board from enclosure and identify the 3 relays. Notice I have removed the tops of the relays to expose the contacts for inspection. Ref A.

Ref B.

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5. You will notice that the assembly is two circuit boards separated and securely joined by numerous copper jumper pins around the exterior edge of all 4 sides. This creates a barrier to accessing the solder solder side of the relays. The only solution to gain access access to the solder side of the board is to cut each of the jumpers into. This is easily done with a Dremel and thin cutting disk. Try to keep the cuts as narrow as possible. possible. We will need to rejoin these these later. Ref C.

Ref D.

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6. Identify and de-solder the 3 relays. I recommend using a quality soldering iron, solder sucker, flux and multi-core rosin solder (60/40) throughout this project. The iron pictured above was adequate but variable temperature and a good wedge tip will make it much easier to achieve good results. You can find excellent instructional instructional videos videos on YouTube if you do not know how to solder. Practice on something something besides this board until you are confident in your abilities. Ref E.

Ref G.

Ref F.

Ref H.

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7. Replace the relay. At this step it would be ideal to just solder in a direct replacement relay. As mentioned above the NEC EN2-B3N3ST relay has been discontinued and there is no known direct replacement to match the pin configuration required. I identified a Bosch style 5-Pin SPDT (Single Pole Double Throw) 40 amp relay will meet the amp and functional requirements to replace the integrated NEC relay. This also gives the added benefit of being able to be replaced should it fail in the future. You will need (6) 12V BOSCH STYLE 5-pin RELAYS 40A SPDT + (6) 5-WIRE SOCKETS. These are easily located on the world’s largest online auction site. I paid about $25 for a 10 pack. Ref I.

Ref J.

Here is the cross reference between the Bosch and NEC relay. It Is Absolutely CRITICAL you match the pins of each circuit exactly. You will see that the NEC is two relays separated in the middle. There will be 2 Bosch relays used to replace each NEC. NEC 1 Pins (1, 2, 3, 5, 10) & NEC 2 Pins (4, 6, 7, 8, 9) Ref K.

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Insert the wires for the sockets into the corresponding holes on the board and solder the reverse side. Tip.. If your relay socket is two large to pass through the opening in the fuse box case, insert your wires through case before inserting in board. Ref L.

Ref M.

Ref N.

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8. Reconnect the two circuit boards. Place the two halves back together with the plastic divider between them. You can file off some material from the divider standoffs standof fs to allow the boards closer together if needed. Use a clamp to hold the boards together while you work your way around the board soldering the copper pins back together. If needed use a piece of wire soldered to the side to span the gap. I did not modify the divider or require extra wire to bridge the gap. Just start in one corner and solder a few pins. Then move to another corner. Once the corners are held it is pretty easy to work around the board. Be sure to solder each one completely. Ref O.

Ref P.

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Ref Q.

9. Close it up and reinstall. At this this point you are basically done. Inspect your your work carefully. Look for any cold solder joints, joints, solder shorts to neighboring contacts or stray wires. Verify and reverify your colors and connections are not only correct in the board but also in the socket. (Red wire indeed does connect to blade 87a on Bosch relay in the socket ... etc.) Close the case on the circuit board. Reinstall in the truck and insert the 5-pin relays into the socket. Reconnect the battery and test the locks. When replacing the fuse box I have read it is not uncommon for the truck to fail to start until the key is cycled numerous numerous times. You may see a fast flas flashing hing or constant red red alarm LED on. This was the case after my re-installation. Ref R.

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Ref S.

Ref T.

Ref U.

This procedure was successful in fully restoring the functionality functionality of the door lock circuit. It is somewhat crude in nature with the relay sockets hanging from the box. A more professional install could be achieved by installing a single multi plug connector at the fuse box and routing a wiring harness to a location were the relay sockets could be more organized. ---- Belew Page 9 of 9