View Full Version : TR4/4A TR4-A Wiring Question

05-25-2007, 08:08 AM
I am trouble shooting an electrical problem in my TR4-A and have a question about part of the lighting circuit. There is a Green/Brown wire coming from the switched side of the fuse block going to the light switch. The diagram I am using (not sure if it is correct) shows that the wire perhaps goes thru a switch mechanism and then connects in with the switch wire for the headlights then on to the dimmer switch. I can't figure out the purpose of that wire. Everything else in the diagram seems to make sense (as much sense as the Prince of Darkness will allow) but I can't figure out the need for a switched hot wire in the light circuit when there is already a hot wire ('always on') coming off the ignition switch. In my car this wire has been burned/melted/corroded at the point it leaves the switch (probably shorted against the steering column) and I would like to know what it should fix when I get it repaired. Excerpt from wiring diagram below. Any help is much appreciated.

05-25-2007, 08:26 AM
That looks like the wire for the "flash to pass" circuit. I'm not that familar with the TR4A, but if the light switch is column mounted, you should be able to pull back on the stalk and the headlights will go on. It's on the ignition side of the circuit, so the ignition switch will have to be on for it to work.

05-25-2007, 08:37 AM
That's exactly what it is! I just looked at the switch and it does have a contact at the back of the switch that closes a circuit when the lever is pulled forward. I had no idea the car was so equipped. (Value just went up)
Thanks for the help.

05-25-2007, 01:21 PM
could your switch be aftermarket or off a 250 or 6?
my 66-67 4A IRS doesn't have this ( I think ?)
Maybe I have an older replacement switch or have never tried the FTP manuver in mine

05-25-2007, 02:18 PM
AFAIK, all 4A's originally had the 'flash-to-pass' feature.

Wrong replacement switch is a possibility, or maybe it's just disconnected.

05-25-2007, 03:22 PM
If your car has it, there should be a spring loaded pivot with the forward motion of the signal lever. Just turn on the ignition and pull the lever forward. If it is wired correctly the lights should flash on.