TR2/3/3A 59 TR3A Intermittant electrical issue,

[Gordon_Dedrick]

1959 TR3A Neg ground. Car runs great, stopped after driving 10 miles and ignition is dead when I turn the key. Bad connections or ignition switch right? Finally get the car going again and get back home after fiddling with the connections on the ignition switch. Get out the test light and I have no voltage at A1 on the control box, wiper switch , or ignition. Car will not power up Fiddle some more and suddenly I have voltage at ALL these points. Made and broke connections on the control box points and I have power again..........for a moment only. I'm baffled where to look. Suggestions? I need to have this car READY for VTR hill climb in three weeks!
Gordon

 

[TR3driver]

Next place to check would be terminal A. If it has power and A1 does not, there is a bad connection or broken wire inside the control box. If A is also dead, check at the hot terminal on the solenoid. If it's dead, there is a bad connection between there and the battery. Most common in my experience is the battery clamp; but could be anywhere including inside the battery. If the solenoid has juice and A doesn't, then it's the ammeter or the wires to/from it. Oh yeah, if the post is hot, try to check on the edge of the ring terminal for the brown wire. There might be a bad connection right there (although that's about the only place I haven't had a problem at one time or another).

 

[Gordon_Dedrick]

OK Randall here are the next tests....... Came home from work, connected battery and had power at A, A1, ignition switch, Solenoid and brown wire on ammeter. Turned key on, no power to dash, and all the power went away to A, A1, and ignition within a couple of minutes. Could it be the ammeter, and can I bypass it and connect the two wires without harming anything as a test, at least? You should also know that I have an alternater instead of a generator. Ammeter was rebuilt by West Valley 4 years ago. What's next, I just don't know where to look? Thanks for your astute knowledge and help.
Gordon

 

[TR3driver]

Yes, you can bypass the ammeter without harming anything. Just run a new wire from the hot post on the solenoid over to the 'A' terminal on the control box. Or if you prefer, pull the two wires off the ammeter and join them together with a wire nut or similar. I wouldn't just twist them together though, as that joint can carry quite a bit of current and you don't want it to get hot.

Did you check at the solenoid after the power "went away" ?

In my experience, it's more likely that a wire is mostly broken at the back of the ammeter. Had that happen a couple of times on my previous TR3A with the clamps instead of Lucar connections. Tinning the end of the wires where they go under the clamp screw (as many people do) only made the problem worse as the strands now flex right at the surface of the solder. Adding some heat shrink tubing across the transition from insulation to bare wire; plus tinning just the very tip of the wire and then trimming it so the screw bore onto bare wire as well as solder seemed to finally solve the problem. Here's a photo taken as I was parting out the car, where you can see the heat shrink.



PS, the extra wire with the in-line fuse is the power to the OD relay. And the loop of black wire visible below the terminals is the shunt I installed to go along with the 60 amp alternator. The shunt effectively recalibrated the ammeter to read 60-0-60 so it wouldn't hit the peg when the alternator was charging at full rate.

 

[Gordon_Dedrick]

As usual......you had the ANSWER..... bypassed the ammeter and voila! Everything works! Thanks for saving me hours of scratching my head. Should I be running a voltmeter instead of an ammeter with the alternater setup? Seems strange that the gage would fail unless the system is putting it under undo strain. Will be reluctant to spend another $100 to rebuild if that is the case. Advice?
Thanks again Randall, you are the very BEST!
Gordon

 

[TR3driver]

They do sometimes fail for no other reason than old age. Might even be worth opening it up yourself, see if you can solder the wire back to the post. They're really simple inside, just a single loop of heavy wire from post to post. (The needle responds to the magnetic field from the loop.)

How is the alternator wired? It probably isn't a good idea to run more current through the ammeter than it is designed for. And yet I much prefer the ammeter, as I feel it is both more informative and more period correct. An ammeter tells you what is happening now, this instant, while a voltmeter only tells you what has happened in the past. The photo above shows my solution : adding a shunt across the ammeter so the instrument itself does not see the full charging current. I ran that setup for 20+ years with a 60 amp Ford alternator; which would hit 60 amps at almost every cold start. And I'll do it again if I decide to put an alternator in the current TR3.