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Ignition Switch?

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TRclassic3

TRclassic3

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Need some assistance on how to diagnose this. The car is a TVR 2500M, TR6 engine and transmission. A little history first. In an effort to resolve an intermittant issue with the swtiched circuit, I ended up replacing the fuse block as there was indication this was the problem. After replacing the block everything worked as it should. I took the car out for a 20 minute run yesterday and upon my return the ignition switch would not turn off the car. I could see from gauges that the switched circuit was turning off ok. I don't see any relationship between the fuse block and the ignition system. Is this correct? Is the ignition switch itself the most likely culprit? Are there other possibilities that I should check?

Unfortuantely I did not have my wits about me and neglected to disconnect the battery right away. I suspect that the Pertronix coil and ingniton might now be toast although I have not confirmed.
 
As best as I recall, you can separate the front and back of the ignition switch. There's a very small phillips head holding them together. Perhaps you can see the problem, once disassembled. MOSS sells the separate pieces....
 
If the gauges are losing power, then I would suspect the problem lies somewhere besides the switch, as usually they run off the same contact as the ignition.

Like most cars of the period, the later TR6 used a ballast resistor for the coil, and a circuit to supply 12v directly to the coil (bypassing the resistor) while starting. I'd be looking at that wire, to see if it is somehow continuing to supply 12v with the key off. Sometimes it is powered by a relay, but most often it's directly from the starter solenoid, so may be shorted there.

When the Stag developed the opposite problem (bypass wire broke loose and shorted to ground, causing the engine to quit intermittently), I just pulled it off and left it. Seems to start just fine without it.
 
This may sound goofy but: the mention of an MGB in this thread hit a (rare) synapse connection... Was the E-brake on when you tried to switch off? There's a piece of wire in an MGB of the same period which can cause allsorts of issues. Not sure of the relationship between TVR, MGB and Triumph but it's worth some investigation! It's tied into the seatbelt warning system and pulls power from the starter hot lead.
 
Thanks all for the response. I'll run down those suggestions.

TVR liked to make things a challenge by using all black wire. They used little colored collars at the wire ends, but over the years many are either missing or the color is no longer identifiable. Keeps life interesting.
 
TRclassic3 said:
Keeps life interesting.
Click to expand...
Similar to my TR3 then. The factory carefully color-coded all the wires, but time and CA smog have conspired to fade all the colors to brown.
 
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