OrangeBobTail
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This is what I did to repair my immobiliser on a '98 Disco V8 ES, use the information contained at your own will. I cannot be held responsible.
The immobiliser, known as the spider, very often rears its head and begins by intermittently not starting, leave it a few minutes and it may well then start. In my opinion the best solution is just to bypass it. The immobiliser cuts 3 circuits, fuel pump, coil & starter motor, any or all of these my be affected.
The full immobiliser circuit is listed in the workshop manual but split over various pages, here is a copy all on one page, a bit easier to understand:
Coil Test - Key in second position. Use a volt meter from the + side of the coil to a good engine ground. You should have battery voltage.
Starter Test - Remove the smaller spade connector on the back of the starter. Use a volt meter from that cable to a good engine ground, you should get battery voltage when an assistant turns the key to 3rd position.
Fuel Pump Test - Pull up the boot floor carpet, remove the ring of screws & lift the plate. Disconnect the wiring connector, use a test meter between the White & Purple wire & a good ground. Get an assistant to turn the ignition to 2nd position, you should get battery voltage for about 2 seconds. Its also worth checking the inertia switch located just behind the washer bottle under the bonnet, just push it to reset it.
If any of these test fail or you get less than battery voltage then the immobiliser may be at fault. Before you start taking things apart check fuses!!
Removal of the spider is a bit of a pain, remove the radio, you may need radio keys, hopefully you know the code. Pull the 3 switches & ashtray opposite. Remove the coin tray and clock, bit awkward but use something like a credit card above and below to push the tabs back then you can pull forward. Look in the dash board behind the items you've just removed, remove 6 the screws. Remove the cup holder, remove the 4 screws behind cup holder.
Pull the 4 heater controls off, remove the 2 screws behind them & remove the fascia. Remove the 4 screws behind the fascia.
Remove the radio cage. Look up & inside from where you've just removed the radio cage and remove the 2 screws.
The entire central dash section should now jiggle free, heater vents will come away attached. You should now be able to see the immobiliser, a black box with black wires coming out of it. Undo the 2 screws, unplug and remove it. Using a flat bladed screw driver pop out the end cover then gently pull out PCB.
If your handy with a soldering iron you will now need to find any dry joints, here are the pins that I found:
Best way I have found is to add a bit more solder to the joint, use a solder sucker to remove all the solder. Then using a little flux reflow the joint. Remember to clean the flux off the board when complete.
Re assembly is the reverse of removal. If you want to test it just plug it back in and try to start. Hopefully you can now start and enjoy your Disco!!
The immobiliser, known as the spider, very often rears its head and begins by intermittently not starting, leave it a few minutes and it may well then start. In my opinion the best solution is just to bypass it. The immobiliser cuts 3 circuits, fuel pump, coil & starter motor, any or all of these my be affected.
The full immobiliser circuit is listed in the workshop manual but split over various pages, here is a copy all on one page, a bit easier to understand:
Coil Test - Key in second position. Use a volt meter from the + side of the coil to a good engine ground. You should have battery voltage.
Starter Test - Remove the smaller spade connector on the back of the starter. Use a volt meter from that cable to a good engine ground, you should get battery voltage when an assistant turns the key to 3rd position.
Fuel Pump Test - Pull up the boot floor carpet, remove the ring of screws & lift the plate. Disconnect the wiring connector, use a test meter between the White & Purple wire & a good ground. Get an assistant to turn the ignition to 2nd position, you should get battery voltage for about 2 seconds. Its also worth checking the inertia switch located just behind the washer bottle under the bonnet, just push it to reset it.
If any of these test fail or you get less than battery voltage then the immobiliser may be at fault. Before you start taking things apart check fuses!!
Removal of the spider is a bit of a pain, remove the radio, you may need radio keys, hopefully you know the code. Pull the 3 switches & ashtray opposite. Remove the coin tray and clock, bit awkward but use something like a credit card above and below to push the tabs back then you can pull forward. Look in the dash board behind the items you've just removed, remove 6 the screws. Remove the cup holder, remove the 4 screws behind cup holder.
Pull the 4 heater controls off, remove the 2 screws behind them & remove the fascia. Remove the 4 screws behind the fascia.
Remove the radio cage. Look up & inside from where you've just removed the radio cage and remove the 2 screws.
The entire central dash section should now jiggle free, heater vents will come away attached. You should now be able to see the immobiliser, a black box with black wires coming out of it. Undo the 2 screws, unplug and remove it. Using a flat bladed screw driver pop out the end cover then gently pull out PCB.
If your handy with a soldering iron you will now need to find any dry joints, here are the pins that I found:
Best way I have found is to add a bit more solder to the joint, use a solder sucker to remove all the solder. Then using a little flux reflow the joint. Remember to clean the flux off the board when complete.
Re assembly is the reverse of removal. If you want to test it just plug it back in and try to start. Hopefully you can now start and enjoy your Disco!!
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