daftpooly Posted October 24, 2010 Share Posted October 24, 2010 After a long drawn out battle to MS my 3.9 serp Disco, many thanks Nige for all your help, I now have a beast that starts from cold (sort of), idles and sounds very nice ; now here is the 'but': After switching off the engine the ignition/ABS/oil pressure lights remain on but very dimly :huh: and the car won't lock with the remote - pull the earth off the battery, put it back on all is well again :rolleyes:. It's a '94, I'm assuming the alarm isn't a spider - although an adult may come along and prove me wrong and to wire the MS I cut and spliced just behind the multi-plug for the Lucarse ECU . Clearly the alarm is looking to the Lucarse ECU for a signal that the engine is off which it now won't get from the bin , I can't see from the wiring diagrams in RAVE what the alarm is looking for - other than to see if it's in Park or Neutral - and the engine turns off on the key. Have any of the resident MS gurus any idea how I can frig the alarm/immobiliser and fix this problem? Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted October 25, 2010 Share Posted October 25, 2010 Sounds like something is backfeeding through the ignition to keep the thing thinking it's alive. What have you got powered by the permanent live feed? I'd start by pulling MS relays to see if the ignition lights go out - then you should be able to isolate the problem to a particular circuit. Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted October 25, 2010 Share Posted October 25, 2010 Thinking about this - I had a problem with the feed light to the alternator doing a back feed, and some clever gurus on here Ian Guildersleeve aka BCC and others sorted it by a diode in line to "Kill" any current. If you wnat one of these to try I can post one. Did I send one ? But you do need a sparkie "Grown up" and not me for this one Nige Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted October 25, 2010 Share Posted October 25, 2010 That was my first thought too Nige, but it's related to power from the alternator backfeeding into the ignition system and keeping the MS unit awake, and therefore the engine running. As the engine is running, the alternator is able to backfeed power into the ignition system. Repeat until someone stalls it This problem is similar, but as the engine is stopped - the alternator is unable to backfeed power. Unless the diode pack in knackered, but then this problem would have shown up before MS was fitted. Quote Link to comment Share on other sites More sharing options...
daftpooly Posted October 25, 2010 Author Share Posted October 25, 2010 The permanent feed comes straight from the input side of the big fuse box in the engine bay - god (Haynes & Lucas) only knows what that little lot feeds . However, a thought has occurred, and it wasn't painful either, when I was checking wiring for the last time before start number 1, I noticed that the +12v EDIS feed didn't drop to 0v immediately when switching the ignition off but discharged linearly. The question is, did the discharge back to 0v occur because I was earthing through the multimeter and would normally carry some current? :angry: If so is there enough current to keep the relays picked enough to maintain the current, hence my problem :( . If a put a diode in the EDIS feed a la HFH's alternator wold this cure the problem? Are there any adults out there who could answer? Quote Link to comment Share on other sites More sharing options...
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