TR6 Rear tail lights not working.

[bigbadbluetr6]

Sometime last years dash lights went out. I didn't think much of it. Last week I tried driving home at night and noticed I didn't have tail lights. I had brake and turn signals. Looking at my wiring diagrams I noticed both the dash lights and tail lights all work off the same wire. I've never had a rheostat which I see the dash lights work off of. I ran a hot wire from the fuse block and attached to the tail light bulb and it worked. I've searched and read a couple other threads and the general consensus is something isn't grounded properly. I'm also certain that is the problem. Is there a certain place under the dash or on the car I should be looking or is it just a crapshoot? Car is a 1973 TR-6. Thanks.

 

[TR3driver]

Well, the first place to check would be the fuse that feeds the dash & tail lights. If the fuse looks OK visually, use a voltmeter or test lamp to check for power on both sides of it. Sometimes fuses look OK but won't carry current. If you find no power at the fuse (with the switch on of course), then the problem is the switch or something between the switch and the fuse block.

Those lights don't share a ground, so it would have to be multiple ground failures to be a grounding problem. Not impossible, but less likely IMO.

 

[Gliderman8]

I also have a '73 and I can tell you that the bulb holders are prone to fail. Before you start tearing into the cars wiring, I would take out the bulb receptacle that is not working and with the bulb in, check the continuity of the receptacle. I've seen the contacts in the bulb receptacle fail.

 

[bigbadbluetr6]

Turns out it was the fuse. I previously took it out and looked at it but I guess it is bad. Should have switched them around a while ago. Thanks guys.

 

[bigbadbluetr6]

Back to the same problem. Looking for a ground now I guess.

 

[poolboy]

Check the fuse again..if it's blown it has found a ground..an unwanted one.

 

[Andrew Mace]

...and if the fuse hasn't blown, and the lights come back again, you've likely got corrosion of some sort on the fuse and on the contacts. Happens a lot on these fuse boxes.

 

[LarryK]

I had a short in the wiring in the boot. Hit a bump lights go out, hit another lights went on. Wires had chaffed over the years bouncing around in boot. Also, check light housings for ground, moisture over the years can degrade metal enough to loose grounds.

 

[TR3driver]

Here's a good article on what goes wrong with those pesky bulb holders, and one method of fixing it.
https://www.buckeyetriumphs.org/technical/Electrical/TR6Sockets/TR6Sockets.htm

The original holders grounded through the clip & fixture; but the replacements I got from both Rimmers & TRF had a third terminal that had to be wired to ground. A much better method of grounding them, but it was a pain to add the ground wire.

 

[mrv8q]

It's easy to disassemble the TR6 fuse box and clean it up for best continuity.

 

[titanic]

+1 on the fuse box. It can be very entertaining. The spade terminals and the fuse holders are connected with rivets and corrosion can take place between the 2 pieces. The metal pieces can be removed, dipped in white vinegar to clean, then soldiered to restore continuity. Or just buy a new fuse box.
Berry

 

[bigbadbluetr6]

Finally got it fixed for good. My dad gave me his voltmeter and I have no idea how to use it or what anything means. So I use it for sometime and after getting frustrated I finally ask him how to use the darn thing. He tells me so I roughly have some sort of knowledge on how this voltmeter thingy works. So initially I start messing with the fuse block and using my new found voltmeter knowledge. I remove most of the wires from the fuse block. Somewhere along the way I hook my taillights and gauges up or they rest against a fuse terminal that has power so wa la I have gauge and tail lights. So my previous position thinking I had a ground problem suddenly became I have no power to these lights so maybe just maybe that's my problem. Call my dad back and explain the situation and while looking at my diagram the understanding of what went wrong is slowing showing up as a solution. Sidenote someone before I got the car made a wood dash so my headlight switch was a 3 way toggle switch. I can see my headlight switch has power because my headlights are working. Maybe something is wrong with the switch. WOW looky there one of the jumper wires is split in half. Well ok let's turn the lights on and connect these broken wires. Well looky there taillights and gauge lights. I make a new jumper wire and bingo my headlights, taillights and gauge lights all work. Stupid wire. This is probably a pretty simple fix and could have been found early on but this is the first time messing with the wiring on my 6. I learned a lot. It was good for me even though I really didn't like Lucas for a time being. As of right now we are on good terms. Thanks everyone for the support and suggestions, I appreciate it.
Eric

 

[TR3driver]

If you can find one, get a copy of the TR250-TR6 Electrical Maintenance Handbook by Dan Masters. I think TRF sells reprints (tho their database site seems to be down at the moment, so I can't check). It starts out assuming you know nothing about electricity, explains the concepts and tools, then walks through nearly every circuit on a TR6 step-by-step. Dan really knows electricity, and is much better at explaining it than I am.

 

[LarryK]

You will find the simplest solution corrects everything on a Lucas system. Just also remember everything is old.

 

[trrdster2000]

Eric, a big help would be a color wiring diagram, much easier to follow, but you will still need help finding where some of the fixtures are. WE can help there.

Wayne

 

[bigbadbluetr6]

My friend has a body shop and he has some sort of wiring diagram book that breaks down each year of the TR-6. I have a wiring diagram out of that book for my year. It is spread out over 2 pieces of paper. Pretty easy to read. Has descriptions right by each section. Since starting to mess with this stuff and read a diagram I am pretty good. I don't know if I'm smarter now because I know how to read the diagram. I think its just caused more headaches. lol Once again thanks for the help.

 

[TR3driver]

My friend has a body shop and he has some sort of wiring diagram book that breaks down each year of the TR-6.

That would almost certainly be the Dan Masters book I suggested above, especially if the diagrams are for US-spec TR6. I don't know of any other source for accurate diagrams (although those have been copied many times, and are available on the 'net at the Advance Auto Wire site).

TRF P/N is RFP605; currently on sale (?) for $44.

 

[poolboy]

BUY IT ! That's an order.