TR2/3/3A tr3 ignition

[prb51]

Guys, replaced my points and using test light I get no juice - not even a dash light when the key is turned to on. Is there a separate elec fuse for the ignition switch and if so where is it.

 

[Mickey Richaud]

If you're talking about the TR3, there are only two fuses, and they're on the bulkhead. Assuming that everything was OK before you changed the points, you may have blown one of them by shorting to the body of the distributor. Also, check the connections on your ignition switch. They are notorious for corroding.

Mickey

 

[Geo Hahn]

TR3 fuses only control the horns and a few circuits (wipers & fuel gauge off hand). Your problem is likely not a fuse.

First check to be sure both battery terminals are well-connected.

Then if your red 'generator' light doesn't come on and the ammeter doesn't twitch when you operate the ignition switch then you might start (as suggested) with that switch as it is a common problem spot.

It is a simple (SPST) switch... the big Brown/Blue wire should be hot all the time, the White wires should be hot when the switch is on.

If the Brn/Blu is not hot start working backwards from there, see if you have power at the A1 terminal of the voltage regulator.

If Blu/Brn is hot and the White wires are not when the switch is on fiddle with the connections on the ignition switch, they may be loose or dirty.

If still no joy it's time to get the multimeter in one hand and the wiring diagram in the other and go huntin'.

 

[sammyb]

I actually had the same problem, and it was a blown fuse. On my TR3, ignition is indeed fused. Now keep in mind that my car was restored by a previous owner, and it's possible that it's not supposed to be fused.

But my impression was that the ammeter is fused, and when that fuse blows, zero juice Mr.Spruce Goose! On my old TR-250, I once was baffled for days when I had no juice, but the battery was fine -- turned out the ammeter had blown, and putting the wires to a single terminal on the back of the ammeter solved things.

But I would trust Geo that on TR3s it isn't supposed to be fused.

 

[danmas]

For an easy to read schematic for your TR3, check https://www.advanceautowire.com/tr24a.pdf

 

[Geo Hahn]

Just a quick review of Lucas color codes may be in order, looking at the primary color of a wire...

BROWN wires are hot all the time and are NOT fused.

WHITE wires are hot only when the key is on, and are NOT fused.

PURPLE wires are hot all the time, and ARE fused.

GREEN wires are hot only when the key is on, and ARE fused

I think an exception to this on the TR3 are the horn wires (Brown/Green) which are fused... later TRs used Purple for this circuit.

 

[prb51]

Ok Guys, thanks, I'll start with the switch. Is the ammeter internally fused?

 

[danmas]

[ QUOTE ]
Is the ammeter internally fused?

[/ QUOTE ]

No, there is nothing between the two terminals except a short piece of wire, formed into a loop. The needle is magnetically coupled to the loop. The ammeter is a short circuit to the power wiring.