"Hot" Wires at the Voltage Regulator

[KVH]

"Hot" Wires at the Voltage Regulator

A couple of problems on my TR4A, and some help please:

The red ignition/warning light at the center of the dash (above the steering wheel) remains slightly lit after the car has started. At night, I can see a faint light. It seems to flicker just a bit if I reach up under the dash and touch the "push in" fitting that lodges in the red reflector housing for the ignition/warning light. Again, it's a very slight red glow, but I have to believe that's wrong to occur.

Any clues why that light is on?

Perhaps related to that:

The three heavy 8 gauge wires at the Voltage Regulator are hot. That doesn't seem right to me. Not warm, but fairly hot.

Is there somewhere I should look for a short, or a loose wire?

These three main main, large wires at the Regulator, have crimp fittings at the spade connector.

Would it make any difference to solder them instead?

A local shop swears that crimped electrical fittings on a TR is an inferior means of assembly, and I'm curious if many folks share that belief.

Anyway, the faint red ignition light glow and the hot Voltage Regulator wire are my latest unsolved TR issues.

Thanks for the help.

 

[tdskip]

Re: "Hot" Wires at the Voltage Regulator

Good morning - the ignition light coming on should be indicative of the generator not producing enough juice. Have you check the volts when it is running.

Hot wires typically indicated too much resistance or too much juice going through the given wiring. If your ignition indicator is on then it is unlikely to be too much current.

Check on this guys...

 

[TR3driver]

Re: "Hot" Wires at the Voltage Regulator

Any clues why that light is on?

The light (on cars with generators) basically compares the voltage at the generator output ('D' terminal on control box) to the voltage at the ignition switch.

In theory, once the cutout relay inside the control box closes, the voltage at those two points will be the same, because they are both connected back to terminal 'A' of the control box (which in turn is connected to the battery through the ammeter).

But if the light is glowing, there must be a few volts difference between those two points, likely indicating a poor connection somewhere (which could be inside the control box).
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Perhaps related to that:[/QUOTE]Yup, almost certainly. The heat is another byproduct of a voltage drop near those wires. There is a bad connection (or possibly several of them) in the vicinity.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Is there somewhere I should look for a short, or a loose wire?[/QUOTE]My suggestion would be to get a digital multimeter (even a cheap one will do https://www.harborfreight.com/7-function-digital-multimeter-90899.html ) and use it to start checking for voltage differences.

For example, to find out if the crimp between the heavy wires and the Lucar connectors is the problem: Set the meter to the 20vdc range, put one probe on the wire where it is exposed (or cut off a tiny bit of insulation if necessary), and the other probe on the connector itself. Wiggle the probes around to get a good connection, then check the voltage reading. It should be well under 0.1 volts. If not, you've found a bad connection that should be replaced or repaired.

Of course, do this with current flowing through the connection. For the brown/white and brown/blue wires, you can just turn on the headlights. To check the brown/yellow, though, you need the engine running at a fast idle (in addition to the headlights).

You can also repeat the test checking between the Lucar connectors and their associated tabs on the control box itself. IMO those are more likely to be the problem spots.

If that all looks good, next check for voltage between tabs A-A1, and A1-D (again engine fast idle, headlights on). These should also be below 0.1 volts.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Would it make any difference to solder them instead? [/QUOTE]
I'm not a fan of crimped connections myself, but usually the factory crimps are pretty good. So I would leave them alone unless the tests above reveal a problem. If you do find a problem, I would replace the connector entirely. Trying to solder the existing exposed wire to the existing connector will be an exercise in frustration IMO, as exposed copper develops an oxide layer that will not take solder (nor conduct very well); plus the original PVC insulation will melt and run at soldering temperatures.

Replacing the connector involves cutting the old one off, stripping back the insulation to expose new wire, crimping on a new connector, then preferably IMO also soldering the tip of the wire to the connector (where it protrudes through the crimp). Ideally, you would then finish the job by sliding a length of heat-shrink tubing over the connector and shrinking it, to both insulate and protect the connector. I also use a second piece of smaller tubing to cover the joint (and melted insulation), which has to be inserted onto the wire before installing the connector.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]A local shop swears that crimped electrical fittings on a TR is an inferior means of assembly, and I'm curious if many folks share that belief.[/QUOTE]This borders on a religious discussion, almost as bad as what oil to use in overdrives

Personally, I don't go around just replacing factory crimp connections, because I've never found a bad one. For the big Lucar terminals, I feel it's much more likely to have a bad connection between the terminal and it's mating tab (which I have seen frequently).

But, once the connector is overheated, it should be replaced. And for replacements, I like the crimp plus solder (and heat shrink) method I outlined above.

 

[KVH]

Re: "Hot" Wires at the Voltage Regulator

Thanks a bunch for the detailed explanation. I'll start checking again to see what I can find.

I'm going to show some ignorance, here, but electrical always does that do me.

Here are a few questions (I know I'll have more):

When you say, "Wiggle the probes around to get a good connection, then check the voltage reading. It should be well under 0.1 volts. If not, you've found a bad connection that should be replaced or repaired," I assume you are saying I should leave the engine running, headlights on, and with the wire still connected to the Voltage Regulator?

Also, just checking, but using that procedure, am I checking resistance or voltage?

Finally, I thought that with the engine running I'd have about 13.5 volts going to the Voltage Regulator. Is that what I'd find if I put one probe to ground and one on the wire instead of both on the wire being tested?

Thanks for the help.

 

[KVH]

Re: "Hot" Wires at the Voltage Regulator

I knew I'd have another question.

If there is a bad connection "between the Lucar connectors and their associated tabs on the control box itself," what can be done about that?

This is all very interesting because my son said his saw that little faint red ignition light (or glow of the bulb)flicker and disappear for a few seconds while I was wiggling the wires at the Voltage Regulator.

Thanks again.

 

[TR3driver]

Re: "Hot" Wires at the Voltage Regulator

When you say, "Wiggle the probes around to get a good connection, then check the voltage reading. It should be well under 0.1 volts. If not, you've found a bad connection that should be replaced or repaired," I assume you are saying I should leave the engine running, headlights on, and with the wire still connected to the Voltage Regulator?

Yes, that is exactly right.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Also, just checking, but using that procedure, am I checking resistance or voltage? [/QUOTE]
Well, what you are really looking for is resistance. But since even a "high" resistance in this case is quite small, it is easier to check for resistance by measuring the voltage drop with current running through the connection. Even 0.1 ohms is way too high for a good connection, and yet it is below the ability of most meters to measure directly.

[geek alert]
Voltage, resistance and current are closely linked by the equation voltage = amps (current) times ohms (resistance). This can be rearranged as ohms = volts/amps; meaning that a resistance can be measured by running a known current through it and measuring the resulting voltage, which is basically what we are doing here. Higher voltage means higher resistance.
[/geek alert]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Finally, I thought that with the engine running I'd have about 13.5 volts going to the Voltage Regulator. Is that what I'd find if I put one probe to ground and one on the wire instead of both on the wire being tested? [/QUOTE]
Yes, that's right again.

I thought you said you were ignorant about electricity!
:laugh:

 

[TR3driver]

Re: "Hot" Wires at the Voltage Regulator

If there is a bad connection "between the Lucar connectors and their associated tabs on the control box itself," what can be done about that?

First step is to try cleaning and tightening the joint. Pull the connector off, and polish the tab with a Scotch-brite pad or similar fine abrasive (old fashioned pencil eraser works well too). ISTR the tabs are plated though, so try not to rub through the plating. You can also smear a thin film of Vaseline or better yet silicone grease (if you have some) on the tab, to help prevent future corrosion.

Then use pliers to gently crush the rounded part of the connector, just a bit, so it will grip the tab tighter. Reinstall and recheck.

If that doesn't do it, then you'll probably have to replace the connector.

However, something I've just recently started trying is soaking such things in Tarn-X. It's probably best to avoid getting it on the stranded wire, so only dip the portion that fits over the tab. Flush it thoroughly with water afterwards, and dry it off. Wouldn't hurt to follow with a flush of WD-40 or similar, either.

I'm still concerned about the long term effects of the Tarn-X, but so far it seems to be OK.

 

[Geo Hahn]

Re: "Hot" Wires at the Voltage Regulator

Then use pliers to gently crush the rounded part of the connector, just a bit, so it will grip the tab tighter...

You may want to do the squeezing using needle nose pliers on the half of the rounded part closest to the wire. That way if you do get it a bit too tight you can still get the female connector pushed on.

 

[KVH]

Re: "Hot" Wires at the Voltage Regulator

Another question of course:

Using that Voltmeter, Randall, you say, "Set the meter to the 20vdc range."

I'm never quite sure when I have to switch to the the DC Current setting that has a maximum of 10 amp load.

Is that what you're saying, though, by vdc range? That I should switch the bottom plug for that specific function, testing current?

(my multimeter instructions are really bad)

 

[TR3driver]

Re: "Hot" Wires at the Voltage Regulator

By "vdc", I meant "volts DC". We're not going to use the ammeter (or ohmmeter) functions for these tests, the meter will only be indicating voltage.

[geek alert]
But FWIW, with just the headlights on (engine stopped), there should be roughly 10-12 amps flowing in the brown/white wire (which leads to the battery through the dash ammeter) and in the brown/blue wire (which feeds power to the rest of the car). Then with the engine running at fast idle (and the lights still on), the generator should take over carrying the load, so there will be at least 10-12 amps flowing in the brown/yellow wire (which is the output from the generator). Might be more, if the battery is discharged, but that doesn't matter for the purpose of these tests.

In general, I try to avoid using the DMM ammeter (current) function around cars. That's partially because the DMM I carry in the car only reads to 200 milliamps, but also because 10 amps isn't really enough and it's too easy to overload the meter. My good Fluke DMM has a fuse (which is kind of expensive to replace), but the cheap HF meters just go up in smoke.

On the rare occasions when I do need to measure current, I use a home-made current shunt, which is just a 1 foot length of 10 AWG wire with two connectors at each end. 10 AWG copper has a resistance of about .001 ohm per foot, so one amp through my shunt gives a .001 volt reading on the DMM.
[/geek alert]

 

[KVH]

Re: "Hot" Wires at the Voltage Regulator

Many of my issues are resolved. These cars spoil me. They're too much fun. If money weren't an object . . .

However, I still have hot leads at the Voltage Regulator.

Instead of .1 readings on my meter, I'm getting .2 to .4. I get that by measuring between the A, A1, and D posts to the connector at those same posts.

The crimp fittings seem tight and clean. I'm hesitant to cut and solder. I'm good at "fixin' things that ain't broke."

How important is it to check the voltage at "fast idle." I've been checking at 1000 rpms. Is that fast enough? And, must the lights be on? The wires are definitely hotter with the lights on. Not so hot anyone would be burned, but hot.

Is there a part of the VR, itself, that would cause the problem?

Both the F and D leads at the Generator seem clean and solid. I did cut and resolder at the D terminal but it didn't seem to change anything.

Next, that faint red glow is still in my dash warning light when the lights are on. Could that be due to a bad bulb on one of my side marker lights? I keep noticing that the bulb is not lit, and have to tap it to make it come back on. Related?

OK, sorry, but one more: My ammeter gauge was registering way high in the positive range after I'd been working on the car and using a work light connected to my battery. So high, in fact, that the pointer disappeared up behind the face plate until I'd driven around for another 10 minutes. What happened there?

Thanks for all the great help here. I have two great TRs because of this site, and only because of it. All the info and advice anyone would need is right here.

 

[TR3driver]

Re: "Hot" Wires at the Voltage Regulator

The crimp fittings seem tight and clean. I'm hesitant to cut and solder. I'm good at "fixin' things that ain't broke."

So, check the voltage between the wire itself, and the control box tab. No voltage means the connection is fine.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]How important is it to check the voltage at "fast idle." I've been checking at 1000 rpms. Is that fast enough? And, must the lights be on? [/QUOTE]The whole point here is to get some serious current flowing in the wires. If your generator will keep up with the headlights at 1000 rpm, then that's fast enough. Mine won't do it until maybe 1500 (indicated, could be high).
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]The wires are definitely hotter with the lights on. Not so hot anyone would be burned, but hot.[/QUOTE]So, you've definitely got a problem.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Is there a part of the VR, itself, that would cause the problem?[/QUOTE]Yes, it's possible. It has several connections inside that could be high enough resistance to get hot, and the heat conducted out to the tabs.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Next, that faint red glow is still in my dash warning light when the lights are on.[/QUOTE]Hmm, I'm not sure just how a TR4A is arranged in that area. On a TR3, the dash lights can be seen, dimly, through the red warning light. The warning light itself is not lit, but the plastic lens seems to pick up the dash lights (which shine on it as well as on the gauges).

Maybe a TR4A owner will chime in here.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]OK, sorry, but one more: My ammeter gauge was registering way high in the positive range after I'd been working on the car and using a work light connected to my battery. So high, in fact, that the pointer disappeared up behind the face plate until I'd driven around for another 10 minutes. What happened there? [/QUOTE]
This still sounds like the regulator is not doing it's job!

Have you double-checked that the 'A' terminal has the brown/white wire to the ammeter; and the 'A1' terminal has the brown/blue that powers the lights, ignition and horns?

Or, it may just be another bum control box, with the defect less obvious than the others. Those things shouldn't be so hard to reproduce, but I have to admit I've never worked with a recent reproduction.