[TR] TR3A OD Wiring Harness Install

Jim Henningsen trguy75 at gmail.com
Mon Jul 23 10:26:29 MDT 2018

Thanks for the info.  Jim

Sent from my iPad

On Jul 23, 2018, at 8:41 AM, Randall <tr3driver at ca.rr.com> wrote:

>> I am
>> going by the wiring diagram in the TR3 owners handbook manual 
>> and want to
>> confirm the setup listed there.
> IIRC there are some small differences between various editions, but all of
> them should work.
>> Wires currently installed to relay by PO which look incorrect based on
>> diagram:
>> C1 - Nothing
>> C2 - one wire to solenoid on tranny OD
>> C4 - 1 wire from OD switch on dash
>> W1 - one wire to body ground
>> W2 - 1 wire from OD switch on dash and 1 wire from starter 
>> push button (hot
>> when ignition on)
> Yup, that's mostly wrong.  One way that does work (from PH 6th ed) is:
> C1 - Constant power from before the ammeter.  Connect either to supply side
> of ammeter, or fuse block terminal with the brown wire.  I recommend adding
> an in-line fuse holder to this wire, with an AGC 5 fuse.
> C2 - to solenoid
> C4 - open (not present on original relay)
> W1 - from OD switch on dash
> W2 - to isolator switches on gearbox top cover.  Both switches are wired in
> parallel, meaning this wire goes to both switches; and the other side of
> each switch is grounded.
> In addition, you'll need a wire from the ignition switch load terminal
> (white wire) to the OD control switch on the dash.
> I also found that it improved relay life to add a solid-state diode (eg
> 1N4001) from C2 to ground.  Orientation will depend on battery polarity.
> -- Randall  

More information about the Triumphs mailing list