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Re: OD Trans Failure (update)

To: "Telewest \(PH\)" <paul.hunt1@blueyonder.co.uk>,
Subject: Re: OD Trans Failure (update)
From: <mjanacek@snet.net>
Date: Sun, 12 Sep 2004 18:04:39 -0400
All,
Well, looks like the solenoid coil is toast. Pulled unit from housing and 
tested with ignition on, in fouth gear and switch thrown. No valve movement 
at all. I did get a small spark when touching coil outer case body to the 
gearbox to ground it so I know I have power to it.
Mike
'79B

----- Original Message ----- 
From: "Paul Hunt" <paul.hunt1@blueyonder.co.uk>
To: <MG-MGB@yahoogroups.com>; "MG-BBS" <mgs@autox.team.net>
Sent: Friday, September 03, 2004 3:47 AM
Subject: Re: [MG-MGB] OD Trans Failure



The quickest way to check the electrics of the solenoid is to check that 
current is flowing in the circuit when it should, unfortunately just 
checking for voltage doesn't eliminate breaks in the circuit between the 
gearbox switch and through the solenoid.  Locate the connector where the OD 
wire in the main harness joins its partner in the gearbox loom, this will be 
amongst the mass of connectors near the fusebox or on the firewall near the 
heater.  On cars with a dash or column manual switch there will be a yellow 
in the main harness and a yellow/red in the gearbox harness.  In cars with a 
gear-lever manual switch, on UK cars it will be a 4-way bullet connector 
with white/browns in the main harness and a white or white/brown in the 
gearbox harness.  On North American cars there is a white from the inertia 
switch to a 4-way bullet connector which may or may not be in the main 
harness, then whites or white/browns from there one into the gearbox harness 
for the OD and one into the rear harness for the fuel pump.

Having found your connector ... part it and connect a test-lamp in its 
place.  With the ignition and manual switches on, and the gearbox in an OD 
gear, the lamp should light.  With all other combinations the light should 
be off.  You can use an ammeter, both my LH solenoids measure about 180 ohms 
which gives about 70mA.

The above relates to the later LH-type OD, I don't know the details of the 
D-type.  It has an additional relay and vacuum switch and it is the relay 
that supplies current to the solenoid, the manual switch just operates the 
relay.  However with the engine off but the ignition on you reputedly can 
hear the D-type relay *and* the solenoid clicking as you operate the manual 
switch, but not on the LH-type.

PaulH. 

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