TR2/3/3A Electrical Issue

[DavidApp]

Have you verified that voltage is getting to the switch from the control box?

David

 

[SteveBones]

The best I can answer is with this:

Control box
A1 Connection - No voltage measure with switch on or not.

Control box -
A Connection - Yes Voltage

A3 connection - Fuse - No voltage measured with switch both on or off.

Switch -
Two connections -No voltage measured with switch on or off.

Light Switch -
No voltage at all three connections. Including the Brown with Blue wire on the switch. Per the handy Moss catalog, the brown wire is always hot.

Amp Meter - Since both the ignition and light switch connections measured no voltage with the switch on or off, I decided to try and find at least one wire where voltage was measured under the dash. The Brown with White wire on the Amp meter did measure voltage.

I am thinking the problem is with the switch. I am also not looking forward to having to remove the light switch since it is more difficult for me to get to. Wish me luck.

One additional item. I started using the voltage light that was suggested earlier. It was much easier for me to use. The multimeter required for me to remember that my car is positive ground and it was more difficult to have the display screen at an angle where I could see the results when working under the dash.

Thank you everyone for all the help.

Have you verified that voltage is getting to the switch from the control box?

David

 

[DavidApp]

Hello Steve

That would suggest that you have a bad control box.

As you can see in the attached photo 'A" and "A1" are connected inside the box.

David

 

[SteveBones]

Hi David,

Thanks. Randall suggested the same thing earlier and I missed it.....oh well. Lessons learned I guess. Now I need to order the control box - voltage regulator. Thanks for catching this one.

Hello Steve

That would suggest that you have a bad control box.

As you can see in the attached photo 'A" and "A1" are connected inside the box.

DavidView attachment 56981

 

[DavidApp]

You are welcome.

Sometimes it is easier to see things when you are standing on the sidelines you are not so deep in all the details.

Good luck with the new control box. There are some modern substitutes for the old box.

David

 

[TR3driver]

Likewise, I thought you said before that you had power on A1 on the control box.

If you are interested, it may be repairable. The link between A and A1 is just a relatively short length of heavy copper wire, wrapped around a relay coil, and likely the wire is OK. You might just need to solder the joint where the wire joins the bottom of the terminal, or add a short jumper.

 

[sp53]

Interesting Randall, so they can be repaired. I bet it was 45+ years ago I bought a Lucas regulator in the red and black box, hooked it up and it toasted right when I started the car. Where it toasted was underneath on those metal strips that go across on the bottom on the center of the A2 strip. At that point, I figured it must be the generator and went and bought a generator and another voltage regulator. So my questions is could Stevebones have a similar problem. Could he purchase a new regulator and have that one toast/ let the smoke out, and he would be back to square one? In other words what made the regulator fail in the first place? Should Stevebones hunt that down first?

Incidentally, I bought the regulator because I figured it was a 50/50 deal on which one was bad and the regulator was cheaper. I saved the regulator in the box and still have it. Perhaps 10 years after toasting it I soldered the break in strip thinking I might try it someday, but never did. I figured the strips were some kind of fuse and never thought about putting a jumper wire between the 2 ends.

other steve

 

[TR3driver]

I wouldn't call it common; but yes, it is very possible to have a generator problem that toasts the regulator.

Until recently, my 56 TR3 was still wearing what I believe to be the original generator and control box. They at least had the right build dates to potentially be original. (I did have to repair both of them several times.) Anyway, the final failure (the one that made me finally decide to go ahead with the alternator conversion) was a shorted field winding, which would have fried the control box if I hadn't managed to burn the health out of my thumb first, and realize what was happening.

Normally, the field resistance is around 6 ohms, so when the box applies 12 volts, the current is only about 2 amps. But in my case, the hot side field coil had internally shorted to the case, making the resistance around 1 ohm and the current around 12 amps! I was wondering why it wasn't working as it should (had to rev the engine up a bit to make the red light go out), but didn't figure it out until I happened to touch the regulator relay (inside the control box) and got a 2nd degree burn. It was well on it's way to letting the smoke out.

Since I really dislike replacing original components that aren't bad (and new components are all too often defective these days), my suggestion is to run through the tests suggested by Lucas to identify the immediate problem; repair or replace the failed component; then immediately run through all the tests again to be certain everything is working (and adjusted) as it should be.
Here is one version of the Lucas tests on the car:
https://drive.google.com/open?id=0B2H2NJt34OffNTc3ODkwYzAtYjRlYS00NDNmLWI0YTYtNjY5ZjQxZTA2NGFm

As a side comment, I'm quite happy with the new alternator conversion. Unlike my previous efforts (on previous cars), this one fits nicely and looks like it belongs there. Same belt I was using with the generator, and it's actually easier to get on and off than with the original generator.

 

[TR3driver]

Another control box failure that I suspect is fairly common : both relay "shunt" coils have one end connected through the coil mounting bolt. But rather than having a positive connection to the bolt, there is a just a brass sleeve in the center of the coil, which is supposed to make electrical contact with the mounting bolt. Over time and heat cycles (both relays get hot even in normal operation plus there is a big resistor underneath that also gets hot), the sleeve works loose and no longer makes solid contact. Depending on which one and when it goes open; symptoms of this can vary from the red light staying on, to the charge current going way high. Charge current too high will toast the generator in fairly short order.

Fortunately, I happened to glance at the ammeter and see the over-current. Since I know what that means, I promptly shut the engine off, and coasted to the side of the road. Some quick trouble-shooting did not reveal the problem (and there wouldn't have been any way to fix it on the side of the road anyway), so I disabled the generator and continued my trip running on the battery.

Since at that point I wanted to try to keep the original control box; I moved it to the bench the next day and started trying to discover what it's problem was. I pretty quickly discovered that the shunt coil on the regulator relay was open, and disassembled it with the intention of replacing the coil with one from another control box. (I've got several of them that came as spares with the various cars.) When I discovered the problem, I added a small jumper from the sleeve to the bolt, put it all back together and it worked fine until the generator died as above.

Being somewhat curious, I went through the box of defective control boxes, and found that most of them had the same problem. (Some on the VR relay, some on the cutout.) That's my evidence for saying it might be fairly common.

 

[sp53]

Yes I like that alternator set up Randall plus one day I might have to go that route. Let me say, I thought I had experienced most problems with a tr3 that stop you cold, but I have not yet anyway had a defective voltage regulator shut me down. Yes I have had the red light come on, but never a shutdown of the car, so what happened so that his car shut down?

 

[DavidApp]

No voltage to the "A1" means no voltage to the ignition switch or the coil therefore no spark.

David

 

[TR3driver]

Right. All of the power to/from the battery (except for the horn and starter motor) flows through the A-A1 connection on the control box.

 

[CJD]

I learned my lesson on the points in the regulator. Setting up mine the cutout was not closing. I figured I would set voltage first, to prevent any chance of a burnout, so I was holding the cutout manually to read the generator voltage. Sizzle! The points get very hot in normal operation!

I bet I spent half my life driving cars with point regulators, and the second half with a combination of solid state regulators. I've only had a single point regulator give up, while at least a dozen solid state ones bit the dust. I was only 16 when the point reg died, and I bet it could have been fixed easily, but I didn't know enough to mess with it. The solid state are mostly sealed in epoxy, so not at all easy to repair...but they DO seem relatively tough, considering they usually sit on the very hot alternator.

Sorry, just rambling.

 

[sp53]

I am confused with this electrical troubleshooting. I think the problem is with the key not making contact in the back of the assembly when moving or the headlight switch is broken and not letting power down to the key. In addition, my headlights and instruments work without the key being turned on; to me that makes sense, the lights should come on without the key. I saw this in your troubleshooting.

3) One other item I noticed. Before this electrical issue, I was able to turn on the instrument lights, parking lights, and headlights on without the key. None of these items are currently working.

I am looking forward to hearing further suggestions. Based on the testing so far, it the issue with the switch, is further testing needed to isolate the problem?

 

[sp53]

I am not sure what your trouble is, but if it does come down to removing the headlight switch, and after I unhooked the battery. I have loosened up the choke if there was no wiggle room under the dash, and made sure temp gauge had wiggle room, and kinda pull the oil gauge line or unhooked it. Then undid the 2 bottom wing nuts on the center section and loosened the upper slotted 2 wing nuts and then teased the whole center section out a couple of inches to make room.
steve

 

[TR3driver]

Perhaps I am confused as well. Is this a separate car, or are you talking about SteveBones' (the OP) 58 TR3A?

SteveBones said

Control box
A1 Connection - No voltage measure with switch on or not.

Control box -
A Connection - Yes Voltage

This is clearly a problem with the control box (or perhaps the connections to it if he didn't probe directly on the A1 terminal).

There might well be some other problem present, but this one fault would cause all of the current symptoms (no lights, no ignition) as that link provides power to the entire car (except horns and starter).

So my suggestion is to fix this one, and see if that addresses all the problems. If not, then he will need to go through the troubleshooting process again to isolate the other fault(s).

Lather, rinse, repeat. While it's certainly normal for only one thing to fail at a time, I've had several times that there were multiple failures. Sometimes two things fail at once, or sometimes something fails while working on something else. Broken wires tend to fall into the latter category, since things get moved and flexed while working on other stuff.

Might even be related failures. Like maybe (strictly as an example), there was a short in the white circuit (which is not fused) and the weakest point was the A-A1 link inside the control box (meaning it was on it's way out already). But the over-current for the short also overheated the contacts in the ignition switch, which oxidized from the heat until they won't pass enough current to run the ignition.

I'm not saying that's likely, in this or any other case; just that strange things can happen sometimes. The solution is to troubleshoot in an orderly fashion until you identify a fault, fix that fault, then try again.

 

[sp53]

My fault I guess I did not read everything through. I went off when he said:

1) Tested both A and A1 contact points on the control box. Both reading approximately a minus 12.5 volts so looks good (My set up is positive ground) . Next up is testing testing and working on the switch itself.

 

[SteveBones]

I realized I never did close this one out. The problem was with the control box. I also had to address an issue with the left turn signal where I replaced the original turn signal wires at the turn signal its self. This is the wiring connecting the turn signal installed on the grill. So through this all I gained a much better understanding of the TR3 wiring. In addition to the helpful comments on this tread, I also used the wiring info located toward the back end of my Moss catalog along with the wiring diagram in the Haynes manual. Knowing what I know now, diagnosing issue would take me 15 minutes to identify the control box as the problem. Instead it took me two are three tries to get it right. I certainly learned quite a bit from the experience. Thanks again everyone for the help.

 

[TR3driver]

Thanks for the follow-up, Steve. Glad you got it working.

I post this so often that I forget which threads have it ... There is a PDF version of the factory workshop manual at
https://drive.google.com/open?id=0B2H2NJt34OffYWZiN2VlZGMtNTkxMi00NGUzLWE4NzMtMGRkODRkYzU3MDU1
which I have updated with a later wiring diagram, modified to LHD and corrected some errors in the original. (Probably should add some of the missing ground wires.)

There were other variations between the two extremes (it also still has the early diagram), but until someone asks, I'm not going to bother to include them. There is one more available at https://drive.google.com/open?id=1Ma-NUXwwAwds9DxYYQgtVFgkclrXyETu
Not corrected, but I've added notes about the discrepancies.

 

[sp53]

Glad to hear you figured it out Steve. The electrical is always rewarding. Now does the regulator need to be re-polarized like the generator?