Posted By : Chris Taylor, 12-Apr-2007,
00:08am
In a 1500, you should have a J type overdrive, and therefore I doubt there is a relay; it doesn't need one. (There was one on earlier Spitfires which
used the D type overdrive).
The overdrive circuit should be live with the ignition turned on, but you won't get feed to the solenoid via the operating switch unless gear lever is
in the 3rd/4th gear plane as there is an inhibitor switch that prevents overdrive operating in lower gears. The inhibitor switch is screwed into the
top of the gearbox, and is a similar type to the reversing lamp switch.
If you have lost the reversing lights as well, it may be a common fuse or common bit of wiring that is at fault. I can only suggest you consult the
wiring diagram for a 1500 of the correct period and work your way systematically "downstream" from the battery to the overdrive solenoid, checking
(against earth, ie the bodywork) at each point that the terminal is at 12 volts with everything set to operate the overdrive (ie ignition on, in top
gear, and overdrive switch engaged). If the input terminal on the solenoid is at 12 volts when switches are on, and there is no sign of movement from
the solenoid, then it's the solenoid itself which is dead
One very simple check of the electrics is to operate the overdrive switch on and off with the gearlever in top gear and ignition on, (but engine OFF)
and listen to see if you can hear the solenoid click in and out whenever you operate the switch. If you CAN hear it, the problem is either adjustment
of the solenoid, or a hydraulic problem in the overdrive. If you can't, then either the supply to the solenoid,or the solenoid itself is defective.
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Posted By : Andrew Szczecinski,
12-Apr-2007, 06:16am
Thats great Chris!
A logical approach testing my way through was something i had considered but in true 'bloke' fashion i had decided to jump the boring stuff such as
checking the wiring to the interesting, chunky stuff such as testing the solenoid and switches.
Im guessing theres some link between the o/d prob and the reversing light problem - looking at the wiring diagram they look like they share some
common stuff.
I have checked the fuses on the bulk head and they're fine - is there any other fuse between there and the o/d and reversing lights?
Thanks - Andy
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Posted By : Colin Wake,
12-Apr-2007, 10:42am
The OD and reversing lights share a common power supply wire.
Green or green and a tracer, goes under the tunnel near the bulkhead just above the chassis, passenger side.
Cheers
Colin
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Posted By : Andrew Szczecinski,
12-Apr-2007, 09:26pm
Managed to get the reversing lights working - the wiring was shot!
However, checked all the wiring through the gear knob switch and theres power all way to the solenoid whe the car in 3rd and 4th.
The solenoid does nothing - no click.
Trouble is i can't get a spanner on the damn thing. Looks like im going to have to butcher one of my spanners to be able to get hold of the
nut. Anyone know what size spanner it is? Its certainly bigger than 24mm
Cheers - Andy
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Posted By : Charles
Bushell, 12-Apr-2007, 10:23pm
It's 1" but you need a thin spanner only about 1/4" wide to get in.