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Re: Ignition warning lamp solved!

To: "Rick Astley" <>, "MG List" <>
Subject: Re: Ignition warning lamp solved!
From: "Steve Murphy" <>
Date: Wed, 22 Dec 1999 21:41:19 -0500
Hi Rick,
    The DOA relay was a Lucas, about the same size as the ISO Bosch but is
cylindrical rather than cubical, so it doesn't fit the ISO socket. The pin
spacing and enumeration is identical to the Bosch, though.  On my car, the
same type of relay is used to trip the starter solonoid.  It appears to be
OE, but I could be wrong.
Thanks for the help!
-----Original Message-----
From: Rick Astley <>
To: Steve Murphy <>; MG List <>
Date: Wednesday, December 22, 1999 10:13 AM
Subject: Re: Ignition warning lamp solved!

>If you have a universal ISO relay (ice cube size) then it is improbable
>it is an original fit. Maybe a previous owner had added extra loads to the
>accessory circuit and was getting too greater voltage drop. Adding the
>would have solved the problem. I may be wrong but I don't believe the ISO
>standard relay was around in '77. If it is that type not only would Bosch
>fit but also almost any relay from any maker around the world.
>----- Original Message -----
>From: Steve Murphy <>
>To: MG List <>
>Sent: Tuesday, December 21, 1999 5:08 PM
>Subject: Ignition warning lamp solved!
>>     Well, I found the reason for my glowing warning lamp.  My car is
>> different from the Haynes diagram which should apply to it, or I'm
>> at the wrong one, or something.  According to what I've seen, the ign
>> switched accessories should be fed through the fuse box via the white
>> On my car, the white wire feeds the field coil of a relay which switches
>> white/brown wire (going to the accessories terminal of the fuse block) to
>> the brown battery buss.  At some point, this relay had failed, and the PO
>> (probably going by the same diagrammes that I was) "repaired" the problem
>> jumping the white wire directly to the fuse block.  Since this wiring
>> "stiff" enough to handle the current demands, the voltage sagged, causing
>> the indicator to glow.  Replacing the defective relay and repairing the
>> wiring cured the problem.
>>     I had some Bosch automotive relays on hand, so I used one of those,
>> was quite surprised that the pin-out was identical to the Lucas, even
>> to the numbering of the pins!
>>     Now I'm wondering if there is an appropriate schematic of the wiring
>> my car (77B) in perhaps a later Haynes manual?  Mine is c1977, and none
>> the diagrammes show such a relay... they all show the wiring going to the
>> fuse block directly from the ignition switch.
>>     BTW, when splicing wiring where it can be exposed to the elements, I
>> crimp and solder the connection, dress it with "liquid tape", then cover
>> with heat shrink.  I've used this in marine applications and it works
>> never had a failure.
>>     Thanks to those who replied to my previous post, I truly appreciate
>> help.
>> Steve Murphy
>> 77 MGB

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