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Triumph TR6 - wiring loom / short circuit

Hi guys.

Wondering if anyone can help me with a short in the stoplight/directional lights/ wiper circuit of my '74 TR6. I have a colored copy of the wiring diagram which is a great help, but I'm having a little trouble isolating each component on the circuit. This is the circuit at the fuse block that has the incoming white wire and the outgoing double green. I've determined one green goes directly to wiper motor, and that appears fine. The other green wire joins the loom and enters the dash area. The problem is each component/switch under dash (stoplight switch, flasher switch, wiper switch) seems to have it's own green wire that exits the loom. How or where does the single green wire that's at the fuse block become multiple copies. Is there a connector somewhere in the loom between the engine compartment and dash area. Are all these components wired in series, with one wire jumping switch to switch (they don't appear to be). I've eliminated any external wiring short by wiring power from fuse directly to brake light switch. Lights work fine. Also disconnected the reverse & neutral safety switches. So I'm pretty confident the short is under dash. Also fuse pops immediately when ignition switch turned to "on".

John

Doug, thanks for the CD. I'm still discovering neat tidbits on it!
JN Neff

Hi John

First off quote: "Are all these components wired in series, with one wire jumping switch to switch (they don't appear to be)" no.

There is a hard wiring together of 6 Green wires within the loom where one wire is from the fuse and 5 go to 5 different branches. This join is not visible and it is NOT a connector. You can see this on the schematic John as a green small circle with the 6 wires all joining there. Not trying to be smart here as I do not know how well you read schematics but a physical connector (one you can disconnect the wires) is symbolized as a black rectangle. A real LUCAS prince of darkness original!!
FYI the "circled X" symbol is the MOLEX connector behind the driver left foot panel that connects the front wiring harness to the rear wiring harness.

OK so the ONLY way to find a short circuit is by logical elimination.
First off I do not think your problem is within the wiring loom. It is external. This is not going to be the easiest task.....sorry to say.
Look at the schematic and you will see all the green wires traveling to a component are connected directly on to that item at a spade connector terminal or are connected at a terminal (wire joiner) before the component. Two examples of this are: The wiper/washer switch which is connected past the voltage stabilizer to an un-numbered terminal to terminal 3 of the wiper washer switch. (remember I said this was not going to be easy)!!! Second is the heater fan switch which has its' green wire attached to terminal #4.
The brake light circuit is easy to disconnect. Simply pull the green spade terminal off the switch.
Now here is where I have a problem. I do not have a 74 which means I do not have a complicated hazard circuit. The symbol "circle /black hour glass" I do not recognize. I am sure it is a connector but do not know where it is located up under the dash.

So John your choice. Disconnect all circuits first then reconnect one at a time to see who is the problem or buy many extra fuses and disconnect one at a time.

Also " I've determined one green goes directly to wiper motor, and that appears fine." Did you physically disconnect it from the fuse and then test? I presume you did.


Have fun John

Rick
Rick Crawford

Thanks for your input, Rick. I'm a dangerous novice when it comes to schematics.

I had already did as you suggest, though I did each component individually. Would disconnect green wire from item, then check for continuity between green wire @ fuse and ground (With positive battery cable disconnected). Every time it showed an open circuit to ground, thus my assumption it's in the loom. Am I missing something?

I believe I found that "circle /black hour glass" connector: its a 6 wire connector with half male/half female on each part. That was probably the easiest to reach after the brake switch!

I'm a little suspect of that "seatbelt Module", as I had trouble with that in the past where it concerned the starter relay; ended up re-wiring around it for the relay. I see that there's a connection between it and the neutral safety switch. I disconnected both the neutral safety switch and reverse light switch at the connectors in passenger foot-well where it passes thru the tranny tunnel. I assumed everything past that on the schematic( including that connection to seatbelt module) was also disconnected. No?

I was hoping I could locate where the one wire becomes 5, then test each wire individually...

John
JN Neff

My guess it's the heater switch power.
That thing is terrible.
Don Kelly

Found the culprit! Gauge Voltage Stabilizer.

Disconnected all components as Rick suggested, then added them back on, one at a time. For some reason, also had to disconnect wiper switch to get proper reading for resistance, but was able to reconnect it without blowing fuse.

Have a new Stabilizer coming from TRF, in the mean time I'll be running without fuel/temp gauges.

Also while having everything torn apart, I wired the brake light switch to it's own fuse, so in the event of another electrical issue :) at least I'll have stoplights (no fun without them in rush-hour on the interstate!)

John
John Neff

John

I quote you "I was hoping I could locate where the one wire becomes 5, then test each wire individually..." as an after comment it would make no use to find the connection as you would have had to cut each wire off in order to test it. Keep in mind it is a solid wire connection not a terminal so you did it the only way and that was to disconnect at the item or the connector before the item.
I have 2 questions as I question weather or not that you have found the EXACT cause of the short circuit problem.

1: did the voltage stabilizer work (where the gauges reading correctly) before or during this short circuit issue?
2: did you just remove the 3 greens from terminal B of the VS and the short (fuse blowing) went away?

Rick
Rick Crawford

This thread was discussed between 24/05/2012 and 27/05/2012

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