View Full Version : TR2/3/3A TR3 Electrical issue - anything obvious?

05-29-2012, 01:15 PM

I've got one more thing to sort out before I register my '59 TR3A. The blinkers work fine until I turn on the headlights. Once the headlights are turned on, the blinkers stop altogether. Is there anywhere on the car where these two systems converge that be a starting point to begin troubleshooting.

The weather is finally nice and I need to be doing more driving and less diagnosing.

Thanks again for your help,

Andrew Mace
05-29-2012, 01:43 PM
Does it have to be headlights, or is it "running" lights as well. I suspect the latter; in turn, that leads me to believe you've grounding issues in the flasher lamp(s).

05-29-2012, 02:02 PM
Thanks Andy,

I'll check tonight. I expected some sort of grounding problem because of the way the PO finished his restoration. He did a really nice job with the restoration, but there are several instances where it was obvious he was tired of the process and began to cut corners on some of the final items. Many of the connections are just wrapped in electrical tape - not that this is bad, it just makes my cleanup a little more arduous.

05-29-2012, 02:23 PM
Sounds to me like the headlights are drawing all the current away from the blinkers. Pay close attention to the grounds as well as all the other connections

Dan B.

Andrew Mace
05-29-2012, 03:14 PM
Many of the connections are just wrapped in electrical tape - not that this is bad, it just makes my cleanup a little more arduous. Maybe not so bad...depending on just what is actually under that electrical tape! Oddly enough, I've found that the original connectors and grounds on Triumphs were pretty good. And when they weren't, it usually is a matter of a few seconds' time to clean them up, and you're good to go again. All too often, electrical tape hides mostly bad splices and other "joys"! :crazyeyes:

05-29-2012, 03:51 PM
Bill - I'm betting your battery is low (especially if you haven't driven enough recently to keep it charged).

If bulbs (signals, running lights, etc.) are the wrong wattage, and sockets are corroded, and wiring is shot, the circuits can supply less voltage than required to "blink" the signals properly. Then you add in headlamps and the current drops below what's needed to operate the flasher (which is usually a very simple "heat operated" device, if yours is original).

Insufficient current will freeze the blinkers.

Try charging the battery until charger shows full charge. Then try the blinker plus headlamp test. Also, remove all bulbs, check wattage, clean sockets, etc.

My wiring is probably even more creative than yours. I live about 30 miles from you, so let me know if you need some help.

I can "supervise" well :jester:


05-29-2012, 05:15 PM
Insufficient current will freeze the blinkers.

I never could quite solve the same problem on my TR3A; even with the battery fully charged, the output voltage would drop low enough sitting in traffic with the headlights and radiator fan on (and the alternator not charging) to cause problems with the turn signals. I finally switched to a "load insensitive" (aka "heavy duty") flasher, the kind that will keep flashing even if one bulb burns out. A Tridon EL13 "electronic" flasher seems to work well for me. You may need to find a mounting clip for it, but my TR3A already had one.

Be sure the mounting clip doesn't grip too tightly though, as the plastic case can deform and break over time if too much pressure is applied.

05-29-2012, 06:29 PM
Once again, I thank all of those who have responded. I came home and went right out to the garage to see if the problem happened when only the running lights were on or only when I turned on the headlights. It turns out to only happens on the passenger side blinker (both front and rear) when I turn on the headlights....with the engine off. When I start the engine, the passenger side blinkers blink, but at half speed to quarter speed.

I'm going to replace the battery this week as I had issues with it going dead this winter - it'll be a good $100 investment in my opinion.

BTW Tom, I said the car wasn't registered, but that doesn't necessarily mean it hasn't been driven (shhhhhhhh).

Tomorrow is another day.....I look forward to seeing if anyone has any ideas on why it would work with the engine on and not off....only one one side.

05-29-2012, 08:25 PM
Tomorrow is another day.....I look forward to seeing if anyone has any ideas on why it would work with the engine on and not off....only one one side.
Same as before, not enough current. Having the engine running (presumably above a normal 500 rpm idle) raises the voltage a bit, which in turn increases the current. And something on the passenger side is reducing the current slightly on that side. Could be a poor ground (particularly at the rear lamps where the factory left out the ground wire), or a corroded socket, or a bulb that is old (their resistance goes up with age). Although not common, I've even heard of the problem being due to a wire that corroded inside its insulation.

PS, another possibility is having the front turn lamp mis-wired. There is a bright filament and a dim one; the dim one draws a lot less current.

05-29-2012, 08:38 PM
Thank you again Randall - looks like I have some more investigating tomorrow - I'll look for the heavy duty flasher tomorrow.

05-29-2012, 09:46 PM
Had this exact same problem with my '3, turned out it was a bad bulb in one of the sockets. Just because a bulb looks OK doesn't mean it is OK. At least I got good grounds out of the deal.

06-20-2012, 07:48 AM
Well, after several weeks of business travel, I finally got a chance to concentrate on my funky electrical problem. I swapped out the flasher unit to the one Randall suggested, replaced all my turn signal bulbs, re-grounded all the turn signal connections and spliced many of the other connections the PO had done. To his credit, he soldered most of his splices but many were just globs of solder covered by electric tape.

After many more hours than I'd like to admit, coupled with the above suggestions, I solved the issue last night - for this I'd like to thank everyone who chimed in. Unfortunately, I focused most of my time on the turn signals and the right hand headlights because when the headlights were turned on causing the turn signals to stop, the right hand turn signals (front & rear) would stay on but not blink.

I scratched my head and stared at the wiring diagram for a long time because the headlight system and turn signal systems don't touch each other. I finally found where the PO had plugged the LEFT headlight ground wire into the connector coming from the control head, thus joining the two systems.

As usual, you guys were right - it was a ground issue! I was just looking at the wrong grounds....