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Wiring loom help please - no power to coil and mystery hot wire

Discussion in 'Rover P6 Electrics' started by Rob1, Jul 7, 2018.

  1. Rob1

    Rob1 Member

    Hi!
    Well work on resurrecting Reg (series 1 P6B) continues. I've got the engine turning but it refuses to fire. I've found that I have power to the coil when cranking the engine - but not when the ignition is just 'on'. It tried to fire on the starter but as soon as i let go of the starter it just lost spark.

    While I was testing stuff I noticed the loom over the left side starting to get warm, as well. So I've removed the factory wrapping and discovered that the culprit is a cream/white wire with a longitudinal pink stripe. Any gurus know what this wire leads to?
    Any common faults that would see power to the coil under starter but not on ignition?
     
  2. Cafcpete

    Cafcpete Active Member

    Don't know about the wire but guess it could be ballast wire. When you are using the starter it is by passing the ballast resister wire and getting a full 12v to the coil. Once you let go of the key the coil is feed by the ballast wire to give around 9v
     
    Rob1 likes this.
  3. Rob1

    Rob1 Member

    The pink/white wire that's getting hot isn't going to the coil....I'll have to rig something up to test the ballast wire....
     
  4. colnerov

    colnerov Well-Known Member

    Hi, Where is it or do you think it's going?

    Colin
     
  5. Willy Eckerslyke

    Willy Eckerslyke Well-Known Member

    White with a red tracer would go from ignition switch to starter solenoid (I'm looking at the 4cyl wiring diagram but should think the V8 would match). I suspect your red has faded to look pink.
    Ballast resistor to coil should be white with a yellow tracer.
     
  6. Rob1

    Rob1 Member

    Is a red tracer a longitudinal stripe? Was a ballast standard on cars exported to Oz? Can't find one anywhere yet...where was the standard location? I appreciate the help! One suggestion given was that the wire was a different resistance causing the ballast...? Auto-electrics are not my forte....
     
  7. colnerov

    colnerov Well-Known Member

    Hi, The ballast resistor is a length of resistor wire spliced into the ignition wire from the ign sw which will get warm, you've unwrapped the warm bit of the loom and found it if you unwrap some more you will find the connections. With the ignition on run is there a voltage?, typically 6 or 8 volts if yes then check the coil and onwards, if not then unwrap some more of the loom and see if the wire has chafed and gone down to earth.

    Colin
     
  8. Vern Klukas

    Vern Klukas Active Member

    White with pink tracer should be radio feed from ignition switch, according to the "official" BLC wiring colours. Primary ignition should be white to the ballast resistor (or coil in non-resistor schemes), white with yellow should be resistor to coil/starter solenoid to coil/starter inhibitor to starter switch and white with black coil to distributor. The ballast resistor are typically a solid colour, but I'm not sure the colour means anything.

    Yours
    Vern
     
  9. ghce

    ghce Well-Known Member

    To put it plainly the P6 has a resistor wire, not a resistor or resistor block.
    If the car fires up on cranking but stops firing off crank then the likely culprit is the resistor wire or an associated connection to it.

    Graeme
     
  10. roverp480

    roverp480 Active Member

    The resister wire in my 2200 diagram is KW which is pink with a white trace ( Not white with pink trace ) If it is the resister wire that is getting hot and the engine stooping after cranking I would suggest there is a short in that wire somewhere. .
     
    Rob1 likes this.
  11. Rob1

    Rob1 Member

    Thanks for your help guys - the radio sounds like a likely culprit as it's been removed - I wonder if the old connection is shorting under the dash, causing all the current to go that way and not to the coil because of the path of least resistance? I'm confident the warming wire is not the coil wire and I can see where it's getting so hot the plastic insulation has melted! Thanks very much for taking the time to advise me, a simple short where the radio was removed might be the whole issue! :)
    I may have been mislead due to the whole battery in the boot thing and been looking for the short in the wrong direction.
    I didn't have a code for pink/white in my book- I'll go looking for KW anywhere in the diagram!
     
  12. Rob1

    Rob1 Member

    I looked at the better diagrams in the service manual and the only place I could find the wire is in the 3500s/series2 loom diagram. I have a series 1 - is it possible my car was a late series 1 and they'd started chanign over the looms?? But it only has the 4 fuses series 1 had....no mention of radio feeds in my diagrams though. This is frustrating as I can't get to the car to physically trace the wire back lol.
    Here's a question - The feed+ from the battery - does it travel up the fire wall or around the front of the car?
     
  13. Rob1

    Rob1 Member

    Hey, if anyone's interested I've gotten back to Reg. The suspect wire IS a ballast wire. Not shown on series 1 diagram in my manual but shown on series 2...I wonder if mine was built during the cross-over? Anyway, I've traced it to the coil, now I just need to find the other end under the dash and replace it. What gauge wire should I replace it with? Does anyone know how many amps it's running? I'm guessing above 35 since my bypassing it through the fuse box blew a number of 35s lol. So back to the books - to see if I can identify it's position on the ign barrel and replace it (It's matched to a different colour wire at the coil and at the ign.....for some reason). Maybe I should put the coil on a relay, or is it ok to have all this juice running through the car?
     
  14. colnerov

    colnerov Well-Known Member

    Hi, The coil only draws about 4 amps. If 35 amp fuses are blowing then there's a fault somewhere, most likely down to earth. The supply for the coil will come from the ignition switch and will be a white wire there. It's normal practice for the coil to be unfused and no relays because it introduces something that could go wrong and you lose the engine.

    Colin
     
  15. Rob1

    Rob1 Member

    Cool, thanks. I'll do more investigation!
     
  16. ghce

    ghce Well-Known Member

    Some one been going for Classic reg with a much newer car?
     
  17. Rob1

    Rob1 Member

    No I don't think so. It's a genuine two owner (I am 3rd), and the last owner has had it for about 20years. There'd be no advantage to re wiring the whole car 20 years ago. It's just odd - but that's not surprising for a car of that vintage...especially not odd for an English car lol? It seems to be a mix of series 1 and series 2 wiring, but maybe the Oz export cars were different for some reason? In any case it's only wires - I'll fix it eventually I'm just looking for 'short' cuts. Pun intended. :)
     
  18. clive P62

    clive P62 Active Member

    Early series 2 v8 also had the 4 fuses in the under bonnet box.
    Clive.
     
  19. Rob1

    Rob1 Member

    Hmmm...adding weight to the cross-over theory! Or more realistically perhaps they just made small changes to the loom design as they went and the manual couldn't be bothered printing each change as a new loom - just either end of the changes.
     
  20. Vern Klukas

    Vern Klukas Active Member

    There may of been some electrical fault years ago (when the car was still valuable) that required a replacement, newer spec harness. I've run across that a few times, though never in a Rover.

    Yours
    Vern
     

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