[Mgs] 80B, melted white-green wire from ignition switch

PaulHunt73 paulhunt73 at virginmedia.com
Fri May 27 09:41:22 MDT 2022

Some amendments:

White/red (not red/white, that is instrument illumination) from the 
ignition switch is for the starter.  The alternator warning lamp has a 
white wire from the ignition switch.

Purple/pink on the ignition switch, not purple, for the 'key in, door 
open' warning and is at earth/ground when the key is in. Purple is the 
fused always hot supply from the fusebox to horns, courtesy lights, 
headlamp flasher etc. but not associated with the ignition switch.


On 27/05/2022 16:09, leon at zaks.com wrote:
> Steve - I fully agree with PaulH. Though the switch may now be 
> compromised but it's highly unlikely it was the cause. The cause is a 
> short circuit in the green/white (G/W) wire. Though there is no fuse 
> indicated in the wiring diagrams for the car there may be one in the 
> lead from the radio to the bullet connector of the G/W wire. If there 
> is a fuse and it is not blown then the short is between the fuse and 
> the ignition switch. The G/W does not go through the firewall.
> There are some mildly sharp edges in the steering wheel supports that 
> the wires run near - could be rubbing caused it or more likely someone 
> working on the radio pulled it a bit much.
> Also - having had a few ignition switches apart the way it is built it 
> would be very hard for it to be misaligned. What can happen is where 
> the shaft from the key mechanism can wear the plastic of the actual 
> switch and cause it to not connect properly - the "If I wiggle it it 
> works" or "If I wiggle it it doesn't work" syndrome.
> I would replace the switch - after you find the problem. Last week I 
> just purchased an aftermarket switch for my b - BPNorthwest has it for 
> under $20, part number BHA5292.
> Here's my comments on what connects to what and why - I'm doing this 
> to help anyone trouble shooting and ignition switch and also to 
> reinforce it in my head.
> Brown (Br) wire is the 12v feed and is always hot.
> Slate is the anti-run on - power only when the key is off.
> G/W is accessory and running. The radio is connected to G/W so you can 
> turn the radio on without the car running.
> White (W) is to the fuel pump (inertia switch first), overdrive, 
> ignition system (with ignition relay on later models) and it feeds the 
> Green wire going to most instruments, turn signals and the like.
> Red/white (R/W) is the power to the starter relay, seat belt module, 
> hand brake, alternator warning lamp. On some models this wire doesn't 
> go directly to the starter relay - it goes to the seat belt module so 
> you can't start the car without buckling your seat belt :)
> Purple is the connection to the horn - it works opposite of the other 
> wires - in the end of the connector coming from under the dash it is 
> always 12v. The purple wire from the connect on the switch should go 
> to ground when the horn is pressed.
> Here's a table of what should connect when on the switch.
> Position 1 is off, then progressively 2 is accessory, 3 is running, 4 
> is starting.
> You can test the switch by disconnecting the plug under the dash - 
> connect one side of a meter or powered continuity tester to the brown 
> wire and checking each of the other wires. Where there is an X you 
> should get a connection. If not, the switch is bad. If you get a 
> connection on a spot that does not have an X the switch is bad.
> Position     S  G/W    W     R/W   Br    Purple
> -------------------------------------------------------------------------
> 1            |  X |        |      |        |    X  |           |
> 2            |     |   X   |      |        |    X  |           |
> 3            |     |   X   |  X  |        |    X  |           |
> 4            |     |        |  X  |   X   |    X  |           |
> leon ...
> https://leonsmgb.com

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