XJ Headlamp Relay control system

Parts supply: We supply a kit for this modification that includes all the parts required ready made (SKJS621) or as components (SKJS622)

Sub loom: this is the loom that goes from the headlamp bulb connector to the multi way push fit connector that then goes into the main loom.

Main Loom: this is the wiring from the fuse box in the engine bay that goes to the push fit connector in the headlamp surround.

Multi way latching connector: New higher amperage connector as supplied in the kit version to connect new wiring to sub loom (4 way)

Latching Spades: these are only required when utilising relay bases as in the kit version.

Cabling tolerances: don't be tempted to cut the wires really short. It is better to allow some slack at the relay location to prevent straining or damage through vibration - always allow some tolerance for slackness where joints are made.

Technical:

Wire specification: Wire for the heavy current cabling should be 2mm sq capable of handling the required amperage.

Each relay is clearly marked as to which pin is which.
Pins 85 and 86 are the coils
30/51 is the switch input
Pin 87 is the output when hot (energised)
Pin 87a is the output when cold (at rest). (5 pin only switched type)

The relays: these can all be ether the switch type (5 pin SKJR20BC) or the non switched type (4 pin - SKJR20B) but should be rated at 20/30 amps for continued reliable use.

Above and below: These are ok for a quick fix or anyone on a budget. Care has to be taken not to crimp so tight that the insulator cracks as this leads to premature failure.

Right: These are the professional type of tools we use and they create a strong rolled over crimp that can also be soldered for added strength

Always Disconnect the Battery when working on the electrics or fuel system lines and components. 

This work will require you to remove both front road wheels and the inner splash guards from the wings - follow the directions given in the Official workshop manuals on how to do this.

A. Existing wiring modification Method

1. At the plug connector that drops into the headlight bowl or surround disconnect the multi 3 way connector (sub harness). It is not essential but we would advise that you then make up a new sub harness using new lamp connectors and the latching multi way connector using new wire.
2. If using the old sub harness remove the 3 way plug and fit the new latching style multi way plug.
3. Attach a draw wire to the 3 way connector on the end of the main loom and pull the plug back into the inner wing. (note on the XJ-6/12 there might not be a plug and you will find singular bullets but the same applies)
4. Cut the three way connector off (or bullets) and terminate the Blue/White, and Blue/Red wires with 6.35mm latching type spades then repeat on the other side of the car.
5. On the quad headlamp arrangement this needs to be repeated for the Blue/white wires to the inner lamps.
6. That completes the wiring to the existing looms.

1. Locate the terminal posts on both sides of the car.
2. You need to run one or two heavy gauge wires from each of these posts toward the front of the car. we found that it makes very little difference to the end result whether each lamp is separately powered on jointly so the single cable or double cable run is a matter of personnel taste.
3. At the bulkhead end terminate and insulate using a ring terminal (6mm)
4. Continue to run the cable down to the new relay location around where your modified the main loom terminates as modified in section A
5. Terminate this end with 6.35mm latching terminals.

1. Using 4mm Ring terminals terminate the ends of two (three on quad setups) new black cables per side. these will eventually need to run back to the location of the original multi way main to sub loom connectors (four (or six) per car)
2. Fix the ring connectors to a good sound earthing point

1. Using new lengths of Blue/White, Blue/Red wire and 2 of the new black earths, pull the required amount of cable (using the draw wire from section A.3. above) back to the location of the original 3 way multi plug or bullets.
2. Connect the new Blue/White, Blue/Red and Black earths to the new latching multi plug at the location of the original 3 way multi plug
3. Back at the relay location, terminate these wires with 6.35mm latching spades.

1. You now have the blue/white, blue/red and black earth wires from the main harness terminated with 6.35mm latching spades
2. two (or four) new heavy gauge positive connections terminated with 6.35mm latching spades at one end and 6mm rings at the other
3. New blue/white, blue/red and black earth wiring to the new latching multi plug at the location of the original 3 way multi plug and terminated in the inner wing with 6.35mm latching spades at the other.

1. Select a suitable location to locate the relay bases that allows all the wires to reach the base comfortably - typically in the inner wing behind the head lamp panel
2. Fix the bases into a suitable location so that the relay terminals will point down when complete. (you may then remove them again for ease in completing termination).

1. Connect the original earths to the corresponding base slot so that they will connect to terminal 86 of all 4 relays
2. Connect the original Blue/white wires to the corresponding base slot so that they will connect to terminal 85 of one of the relays
3. Connect the original Blue/Red wires to the corresponding base slot so that they will connect to terminal 86 of the other relay.

1. Connect the new loom Blue/white to the relay terminal 87 on the corresponding relay (i.e. on the relay controlled by the original Blue/white wire that you connected to in 2 in the preceding section)
2. Connect the new loom Blue/Red to the relay terminal 87 on the corresponding relay (i.e. on the relay controlled by the original Blue/Red wire that you connected to in 2 in the preceding section)
3. Connect the new heavy gauge brown wire from the terminal post location to pins 30/51 on all four relays.

1. Affix the bases to their location points if not already done.
2. Attach the new brown heavy gauge ring connectors to the terminal posts on the fire wall
3. Plug in the relays to their bases.
4. Connect your new sub looms to the latching multi plugs in the head lamp bays.
5. Plug in a test unit or the correct headlamp bulb to each of the headlamp connectors
6. Test the system.