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SteveBones
12-30-2018, 11:47 PM
I have "new" electrical issue with my 1958 TR3A. When I turn the key, nothing happens. What I mean is that the red generator warning light is dark, the fuel gauge stays at empty, and the amp meter does not move. The horn does work. This happened after driving the car for 20 minutes with no issue. A few minutes after shutting off the car, and turning the ignition key to the on position, nothing happened. I just started trying to track down the problem. So far I have done the following:

1) Checked the battery connections. The ground wire was loose at the terminal. I tightened and no change.
2) Fuses. These are the original type fuses. I removed and cleaned the fuse connection ends. No change.
3) I plan to use a voltage meter with the resistance setting to determine is the ignition switch is working correctly.
4) I will take a look at the wiring diagram and start working from the ignition switch to see if there is a bad connection.

Based on what I describe, is there any recommendations on what else to do to isolate this electrical issue?

Thanks,

CJD
12-31-2018, 12:30 AM
I would look closely at the ignition switch itself. The wires can easily loosen under the set screws.

SteveBones
12-31-2018, 01:43 AM
Thanks for the suggestion on where to start. I looked under the dash and lightly pulled on the wires to see if they were snug. Based on your suggestion, I am thinking of going a step further by loosening the set screws, removing the wires, and the re attaching.


I would look closely at the ignition switch itself. The wires can easily loosen under the set screws.

TR3driver
12-31-2018, 02:22 AM
Before starting to take things apart, I suggest some simple tests with a test light (or voltmeter/DMM/what have you). The switch is certainly a possibility, but there are lots of others.

Since the horns work, I'd start with terminal A on the control box to ground. It should be hot (12V) all the time. If not, there is a problem along the circuit from the starter solenoid to the ammeter, and ammeter to terminal A. Could also be a bad ammeter.

Also check terminal A1. If it's not hot, the control box has failed.

Then with the key on, probe both terminals on the back of the ignition switch. If you feel around a bit, you should be able to get on them without sticking your head down there. If neither one is hot, the problem lies along the circuit from A1 to the headlight switch, to the ignition switch.

If one is hot and not the other, the switch has failed.

If both are hot, check next at A3 on the fuse block (one white wire). Etc.

SteveBones
12-31-2018, 03:07 PM
Extremely helpful Randall. I will do as you suggested below. I do have a voltmeter and have used it to isolate an electrical issue on my other Triumph about five years back. I will let you know what I find out.

Thank you


Before starting to take things apart, I suggest some simple tests with a test light (or voltmeter/DMM/what have you). The switch is certainly a possibility, but there are lots of others.

Since the horns work, I'd start with terminal A on the control box to ground. It should be hot (12V) all the time. If not, there is a problem along the circuit from the starter solenoid to the ammeter, and ammeter to terminal A. Could also be a bad ammeter.

Also check terminal A1. If it's not hot, the control box has failed.

Then with the key on, probe both terminals on the back of the ignition switch. If you feel around a bit, you should be able to get on them without sticking your head down there. If neither one is hot, the problem lies along the circuit from A1 to the headlight switch, to the ignition switch.

If one is hot and not the other, the switch has failed.

If both are hot, check next at A3 on the fuse block (one white wire). Etc.

SteveBones
01-02-2019, 05:04 PM
Hi Randall,

A brief update and question.

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.

2) Regarding the A3 on the fuse block. Does this check to make sure it is hot - also 12volts? Does this A3 test only work if the switch is working and turned on? I do plan to check the switch out first.

Thanks for all the help from you and the others. The quality and willingness of the fellow British Car Forum members to share their expertise is so greatly appreciated.


Before starting to take things apart, I suggest some simple tests with a test light (or voltmeter/DMM/what have you). The switch is certainly a possibility, but there are lots of others.

Since the horns work, I'd start with terminal A on the control box to ground. It should be hot (12V) all the time. If not, there is a problem along the circuit from the starter solenoid to the ammeter, and ammeter to terminal A. Could also be a bad ammeter.

Also check terminal A1. If it's not hot, the control box has failed.

Then with the key on, probe both terminals on the back of the ignition switch. If you feel around a bit, you should be able to get on them without sticking your head down there. If neither one is hot, the problem lies along the circuit from A1 to the headlight switch, to the ignition switch.

If one is hot and not the other, the switch has failed.

If both are hot, check next at A3 on the fuse block (one white wire). Etc.

TR3driver
01-02-2019, 07:29 PM
Yes, A3 is only hot with the key on, and should be close to battery voltage (12 volts).

SteveBones
01-02-2019, 08:07 PM
One more question. When I am using the multimeter to measure voltage, since my TR3 is set up for positive ground, do I put the red (hot) wire on ground, and put the black (common) wire on the circuit (A, A1, A3)?

Brief update. I did check the switch itself. Even took it off to bench test by measuring resistance. I also cleaned the contact area. The switch is working fine.

Also, As mentioned previously, I measured the voltage for A, and A1 on the voltage regulator. Both A and A1 measured approx 12.5 volts.

Next step is to measure voltage at A3. I will try to do this sometime tomorrow.




Yes, A3 is only hot with the key on, and should be close to battery voltage (12 volts).

TR3driver
01-02-2019, 09:17 PM
With respect to the meter, think of red as positive and black as negative. So, for a positive ground car, the red goes to ground and the black probes for power.

You might want to double-check the voltages at the switch, with the switch on and a load applied. A resistance like 1 ohm can be hard to measure; but is enough to keep it from powering the car. Also, sometimes things get hot and the resistance goes up when powering a load.

SteveBones
01-03-2019, 08:02 PM
Here is my update:

1) A3 voltage was measured with the key on. Measurement was 0.00 volts. I also measure the other side of the fuse connection with the brown wires. I did measure approx 12.5 volts.

2) Switch voltage measurement was also 0.00 volts with the key in the on position.

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?




With respect to the meter, think of red as positive and black as negative. So, for a positive ground car, the red goes to ground and the black probes for power.

You might want to double-check the voltages at the switch, with the switch on and a load applied. A resistance like 1 ohm can be hard to measure; but is enough to keep it from powering the car. Also, sometimes things get hot and the resistance goes up when powering a load.

TR3driver
01-03-2019, 09:23 PM
Ok, so you found power at one end of the NU wire (A1 on the control box) but nothing at the other end (one of the ignition switch terminals). It daisy-chains through terminal A on the headlight switch, which is where I would look next (especially since now it appears the headlight switch isn't getting power either).

DavidApp
01-03-2019, 09:42 PM
Hello Steve

Are you getting battery voltage at "A" on the control box? If you are you should have it at "A1" as well.
If you do not have voltage at "A" you probable have a bad Ammeter or bad connection.
If it is at "A" but not at "A1" a control box problem.

David

sp53
01-03-2019, 09:49 PM
I am probably missing something, but isn’t the ignition just an on- off switch and you could hook a jumper across the back and see if the light comes on ---or would that hurt something?

SteveBones
01-03-2019, 09:53 PM
Sounds good. Based on what you suggested earlier and the latest test results, I went through the wiring diagram to see if I could figure out what to do next. I was thinking the next step was to look at the headlight switch but was not sure. Thank you for confirming.

I have done quite a few things over 40 years fixing various items on my TR's. This is the first time having to resolve this type of electrical issue. I am starting to feel better knowing I am getting close. Without your help I am not sure how long and how much frustration I would have endured trying to fix this. Many thanks.


Ok, so you found power at one end of the NU wire (A1 on the control box) but nothing at the other end (one of the ignition switch terminals). It daisy-chains through terminal A on the headlight switch, which is where I would look next (especially since now it appears the headlight switch isn't getting power either).

SteveBones
01-03-2019, 10:01 PM
Thanks David. Next step will be looking at the headlight switch wiring. I feel like I am getting close.


Hello Steve

Are you getting battery voltage at "A" on the control box? If you are you should have it at "A1" as well.
If you do not have voltage at "A" you probable have a bad Ammeter or bad connection.
If it is at "A" but not at "A1" a control box problem.

David

SteveBones
01-03-2019, 10:08 PM
Makes sense what you are suggesting. Randall's method has been great in getting me closer to identifying the issue. What he is suggesting is based on starting at point A and moving back step and step through the wiring. This is the first time for me using this approach and also the first time having to address this type of electrical issue. As I go through what Randall is recommending, it is looking like a solid approach and helps to make sure I do not miss something.


I am probably missing something, but isn’t the ignition just an on- off switch and you could hook a jumper across the back and see if the light comes on ---or would that hurt something?

TR3driver
01-04-2019, 12:20 AM
BTW, there is no reason you can't connect a jumper across the ignition switch. I have been known to drive that way, when necessary. Just be careful that it can't touch anything else, as there is no fuse in the feed to the switch and a short can easily set the car on fire.

But as noted, I much prefer a systematic approach, rather than guessing.

CJD
01-04-2019, 11:19 AM
These switches are very robust...but they do use bakelite, which is very brittle. I would take a test light and follow the power in and out of each switch until you find the break.

TR3driver
01-04-2019, 12:29 PM
When my TR3A ignition switch failed, the contacts were worn until they no longer made solid contact. The moving contact is spring loaded, but can only move so far.

SteveBones
01-04-2019, 01:49 PM
Good point. I did test the switch, but after going through Randall's earlier email, I did not test the voltage correctly. This morning I will test the voltage of the switch by what was suggested earlier which is copied below:

Then with the key on, probe both terminals on the back of the ignition switch. If you feel around a bit, you should be able to get on them without sticking your head down there. If neither one is hot, the problem lies along the circuit from A1 to the headlight switch, to the ignition switch.

If one is hot and not the other, the switch has failed.


These switches are very robust...but they do use bakelite, which is very brittle. I would take a test light and follow the power in and out of each switch until you find the break.

DavidApp
01-04-2019, 02:58 PM
Have you verified that voltage is getting to the switch from the control box?

David

SteveBones
01-04-2019, 08:23 PM
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
01-04-2019, 08:50 PM
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.

David56981

SteveBones
01-04-2019, 10:33 PM
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.

David56981

DavidApp
01-04-2019, 11:30 PM
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
01-05-2019, 11:28 AM
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
01-06-2019, 11:54 AM
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
01-06-2019, 12:22 PM
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=0B2H2NJt34OffNTc3ODkwYzAtYjRlYS00NDNmLWI0Y TYtNjY5ZjQxZTA2NGFm

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.
https://i.imgur.com/X4GAP8v.jpg

TR3driver
01-06-2019, 12:43 PM
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
01-06-2019, 02:38 PM
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
01-06-2019, 06:38 PM
No voltage to the "A1" means no voltage to the ignition switch or the coil therefore no spark.

David

TR3driver
01-06-2019, 09:53 PM
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
01-07-2019, 12:55 PM
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
01-08-2019, 10:37 AM
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
01-08-2019, 11:33 AM
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
01-08-2019, 02:03 PM
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
01-08-2019, 02:54 PM
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
02-10-2019, 07:14 PM
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
02-11-2019, 12:50 AM
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=0B2H2NJt34OffYWZiN2VlZGMtNTkxMi00NGUzLWE4N zMtMGRkODRkYzU3MDU1
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
02-11-2019, 01:20 PM
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?

TR3driver
02-11-2019, 01:42 PM
Nope, control box doesn't care.


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?