Steve:
If you have a universal ISO relay (ice cube size) then it is improbable that
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 relay
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.
Rick
----- Original Message -----
From: Steve Murphy <k8vo@flyingbeers.org>
To: MG List <mgs@autox.team.net>
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 looking
> 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
wires.
> On my car, the white wire feeds the field coil of a relay which switches a
> 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
by
> jumping the white wire directly to the fuse block. Since this wiring
wasn't
> "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,
and
> was quite surprised that the pin-out was identical to the Lucas, even down
> to the numbering of the pins!
> Now I'm wondering if there is an appropriate schematic of the wiring
for
> my car (77B) in perhaps a later Haynes manual? Mine is c1977, and none of
> 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
it
> with heat shrink. I've used this in marine applications and it works
great,
> never had a failure.
> Thanks to those who replied to my previous post, I truly appreciate
the
> help.
> Steve Murphy
> 77 MGB
>
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