TR2/3/3A tr3a electrical troubles

[Jim Lee]

Hi all.
It has been a while since I have posted but that is mostly because my black beauty TR3 has been running like a champ. Right now though I really need some help. <span style="font-weight: bold">I am absolutely stumped as to what is going on with my 1959 TR3. </span>I drove it to work a month ago and it was running great right up until I got to the parking lot where it idled too low and cut off. No big deal, push the button and start it up again. But no starting. Only the sound of the solenoid clicking. Jumped battey. Still only clicking of solenoid. Tried to roll start it. Nope. Towed home and thought for sure that all I needed was a new solenoid. New solenoid. Same deal. A bunch of clicking. Finally nothing. Ok. Removed the starter to test it. Tested great. Battery? Tested fine. So I have a good charged up battery, a good starter, a new solenoid. <span style="font-weight: bold">Now I turn the key and absolutely nothing happens.</span> https://www.britishcarforum.com/bcforum/images/icons/default/mad.gif I have 12+ volts going to the solenoid. Press that button and absolutely nothing.

Next stop is to pull the center panel and see what kind of awful things have happened there. <span style="font-weight: bold">I have never turned the key and had absolutely no response.</span> I guess I need to start with the ignition switch. There is definitely something preventing the juice from getting to...anywhere right now..

Any and all ideas, suggestions, condolences would be most welcome. I have to admit that I do have a new wiring harness but I am scared to death to try installing it. I am wondering if this is the time to grit my teeth and go for it. I just cannot imagine getting it right though. Very intimidating...but those wires are approaching 50 years old....
I will report back on what I find at the ignition switch. We are talking original wiring so I am mentally prepared for anything. I cannot go through a Carolina never ending Fall season without my Black Beauty running.

Thank you all very much,
Jim Lee

 

[DNK]

How the battery?

 

[TR3driver]

Pushing the rubber 'button' on the solenoid should cause the starter to crank the engine, no matter what state the rest of the harness or dash switches are in. It would still work even with the harness totally removed!

Get a cheap digital multimeter and do some basic troubleshooting, instead of just changing everything in sight. The circuit isn't too complicated, basically we have from the battery to the solenoid, solenoid to starter, starter to engine block, engine block to frame (ground strap at the LH motor mount), body back to battery.

Since I think you have a ground problem, I'd start at the solenoid, checking between the output terminal and the solenoid housing (which should be grounded to the body). You should see roughly 12v here when you push the rubber button. If not, move back along the circuit towards the battery until you do find 12v (with the button pressed). The starter draws a huge amount of current, so a connection that will pass enough current for anything else may not pass enough current for the starter (which is why you make the tests with the button pushed). The problem might even be inside the battery, I have seen batteries that tested "OK" but wouldn't turn a starter.

If you do find 12v at the solenoid output; repeat the check at the starter motor (using the motor housing for the ground of your meter). If you also get 12v here, then the starter is bad (no matter how it tested on the bench). If not, work back along the circuit until you find 12v.

 

[DougF]

I'd agree with Randall. My 3 had the same problem several years ago. I cleaned a few connections and it's been fine since.

 

[NickMorgan]

Sounds like a grounding issue to me too. Your engine will turn over by hand, or if you put the car in gear and push?

 

[Adrio]

I agree with Randall. I would check the connections as well. A simple check of connections is to measure voltage across the connection. There should be none. If when you push the button the voltage across a connection goes from (near zero) to appreciable then that connection needs to be addressed (that is cleaned or otherwise renewed). As Randal says the starter circuit is simple and it draws a lot of current. So it does not take much resistance in a connection for that to be the high impedance portion of the circuit and thus not leaving much voltage for your starter.

Remember the mechanical connection of your starter to the block is part of that electrical circuit.

 

[NutmegCT]

Just a 2¢ here ...

Don't always trust a volt meter to give the "strength" of a battery. I prefer using a load tester. One way around that for me was seeing if the horn blows; the horn draws a heavy "load" of current. A pitiful weak "buzz" from the horn tells you the battery is very weak, despite what an inexpensive volt meter showing close to 12v.

Tom

 

[Jim Lee]

Thanks to all and most especially Randall.
Randall wrote:
"Get a cheap digital multimeter and do some basic troubleshooting, instead of just changing everything in sight"

The only thing I have changed is the heavy duty wire going from the solenoid to the starter.

"Since I think you have a ground problem"
I agree completely which is why I have checked out the engine ground strap to make sure it was attached and tight. Starter is metal on metal to engine which is grounded to frame by strap.

"I'd start at the solenoid, checking between the output terminal and the solenoid housing (which should be grounded to the body). You should see roughly 12v here when you push the rubber button"

I always have 12v+ at the top of the solenoid. When I push on the button I can detect some really low number like .3 volts at the bottom (output to starter) connection. 0 volts (as I would expect, when I am not pushing the button.

I think that this is the point at which I am stuck in the mud:
"If you do find 12v at the solenoid output..."
I cannot get more than this nominal amount of voltage to the bottom/output side of the solenoid.

Sound like my brand new solenoid is not grounded?

Thanks to all.

Jim Lee

 

[angelfj1]

Tom is correct. Volts only mean very little.

I suspect the solenoid. If the contacts are badly pitted (these are inside and you can't see this without an autopsy)you will get poor conductivity and no starter action. With a good solenoid, while cranking over, there should be almost zero voltage drop across the contacts.

 

[TR3driver]

I always have 12v+ at the top of the solenoid.

Does that include when the rubber button is pushed, checking to the solenoid case? If so, then the solenoid is bad.
Another quick check to ensure that's the problem is to meter across the two big solenoid terminals. When you push the rubber button, this voltage should go to almost zero (no more than perhaps 0.1 or 0.2 volts). If not, the solenoid is definitely toast.

 

[emmett1010]

Hello:
If the car wouldn't roll start, the coil must not have 12 volts!
Coil voltage comes off the battery side of the solenoid, through the ignition switch-- sooo either the battery is shot, or bad cable, or maybe a poor connection.
Emmett

 

[Jim Lee]

"If the car wouldn't roll start, the coil must not have 12 volts"

I am not even at 'car starting' stage. I am just trying to get the 12 volts at my battery to my starter. I tested it tonight and if we call the 'input' (from the battery) post on the solenoid the upper and the 'output' (to the starter) the lower, than I measure 12 volts always at the upper and 0 at the lower until I press the switch which makes some very subtle noise like electricity is trying to get somewhere and is not making it while the lower solenoid post measures .2 to .3 volts.

There is definitely something not grounded somewhere. What is strange though is that the solenoid is brand new. I will put in the old solenoid, although that was just clicking before when I first got stuck at work. I am thinking about the solenoid not properly grounded to the body. Is it possible to measure the resistance of the solenoid to see if it is working?

There HAS to be a ground gone astray as the car and battery were running great right up until it stalled out on my way to work. Also I turn the ignition key and there is absolutely nothing now. Before there was some power but I could tell that it was very, very little, even though the battery was fully charged. Is there a single ground wire that could keep the ignition from turning on, no lights, no electric pump noise, no nothing, and also keep the 12 volts from getting from the battery to the starter? I am beginning to wonder if I should attach a seperate, additional wire from the engine to the body to see if by some bizarre circumstance my main ground wire is not doing its thing. There has to be some very important connection (ground I think) that is not being made.

I have a feeling this is going to be an excellent learning adventure.

Thanks,
Jim Lee

 

[Andrew Mace]

...I am beginning to wonder if I should attach a seperate, additional wire from the engine to the body to see if by some bizarre circumstance my main ground wire is not doing its thing. There has to be some very important connection (ground I think) that is not being made. ...

Great idea, and very easy to do. Look for your jumper cables and use them.

Many years ago, I had a similar problem with a Volvo 144 suddenly losing electrical power. Battery was fine, but a major ground cable (probably the one from the battery; it was so long ago I no longer remember) was shot. A friend of mine lent me his jumper cables, one of which I simply ran from the battery negative terminal to a good ground. Got me the 100 miles home (from Limerock Park), where I could then easily and properly make a fix.

I suggest taking one more look at all the major cables and their connectors and connections to other parts. For example, one of the battery cables might be otherwise fine, and perhaps even the terminal end might be fine, but the physical connection between the two might have seen better days.

 

[NickMorgan]

Have you tried simply jump starting the car from another battery? I suspect your battery is dead if you are not getting any lights as well.

 

[Don Elliott]

Turn on the ignition key. With a mother of a huge old screwdriver, connect (short across) the two bolts on the front end of the solenoid. If the starter starts, the problem lies with the solenoid.

Make sure that the lugs connecting to the solenoid are clean and tight.

What happens when you push the rubber button on the rear of the solenoid as Randall suggested above ?

 

[Jim Lee]

Yep. When I first stalled out at work, thankfully in the parking lot. Tried jumping, only clicking at the solenoid. Triple A tow guy tried to jump it also.
Then we tried to roll start it. No luck.
I have taken the battery down to my local store and they have done a load test on it and it passed. Which bummed me out almost as much as when they tested the starter and it passed with flying colors.

I think my next move will be to use a jumper cable to test grounds. First from negative battery post. Then from engine to chassis. Then if that is all good use the big old screwdrive across the solenoid posts trick.

Wish me luck. I will report back.

Thanks,
Jim Lee

 

[Geo Hahn]

One other thought -- that big connection on the back of the starter (cable from solenoid) can be loose or dirty creating to much resistance to crank.

Often if this is the case it will get warm after attempting a start. Even a little oil on it is enough to cause a problem.

Solution of course is to assure it is clean & tight.

 

[TR3driver]

Is it possible to measure the resistance of the solenoid to see if it is working?

In effect, that is what you are doing with the second test I suggested. The resistance between the two big posts has to be very low (when the solenoid is engaged or the button is pressed), much lower than you can measure with a normal ohmmeter/DMM. But by measuring the voltage across the posts with the solenoid passing current to the starter, you are really checking the resistance (Ohm's law says the voltage is equal to the current times the resistance).

Just to be clear, the solenoid does not need to be grounded when you are pushing the rubber button on the back of the solenoid. The solenoid ground is only required for it to work when using the pushbutton on the dash.

Also to be clear, my battery passed the store's load test as well; even though it was defective. There's just no substitute for actual in-circuit real-world testing. The store's load test is only 100-150 amps, while a healthy TR3 starter draws three times that much (initially).

Which of course could be the problem; I have seen Lucas starters short internally and draw much more current than normal. But if that were the case, and everything else was up to snuff, you should be able to see and feel the generated heat. In my case, the insulation on the positive battery lead literally melted and started smoking after just a few seconds of cranking.

 

[TR3driver]

With a mother of a huge old screwdriver, connect (short across) the two bolts on the front end of the solenoid. If the starter starts, the problem lies with the solenoid.

Problem with that test is that it may damage both the screwdriver and the solenoid; plus may give a false indication. If the starter cranks the engine, you do know the solenoid was bad. But if you don't get a good solid connection between the screwdriver and the post, the engine still might not crank even if the solenoid was the problem.

And of course there could be multiple problems.

Something else no one has mentioned : Try holding the rubber button in for 10 seconds or so, and then feel all the connections to see if any of them got hot. The one that burns you is bad

 

[Jim Lee]

Groundless!!!!!!!!

Ok. My lesson is going to be Grounding (Earthing if you are one of our cousins across the sea) 101. I finally measured the voltage from my positive post to the grounding point that my negative post cable went to just above my battery on the firewall/sheetmetal/grounding point of my car. Measured like .3 volts instead of the 12v+ it should does on my other cars. I cannot get 12 volts showing without putting the negative lead directly on the positive terminal of the battery.

The .3 volts that I do get on very clean metal with the negative lead, is reminscent of the .3 that I get when I push the big rubber button on the solenoid and measure on the output/bottom terminal that goes to the starter. So I think it is safe to say that I definitely have a grounding problem. I even dragged the battery out of another car that runs great to see if it had anything to do with the battery (a battery that has been load tested, as best they can at the auto parts place). Nope, same deal.

So what I need to know is why in the world is my chassis, not to mention engine, which the starter is grounded to, NOT serving as a ground? On my other ancient mariner car ('63 Tbird) I can do the same test and get a healthy 12v+ when grounding to almost any piece of metal on the chassis or motor. Painted or not. How in the world have I managed to 'deGround' my TR3? I have to be missing something embarrasingly simple. I also have a feeling this is going to be a huge lesson in the vagaries of elderly auto electrics. What I am really, really curious about is how the car was running so well all Spring, then at a fateful moment while gliding into the parking lot at work the Lucas Gods suddenly turned against me. Why me? Why then/now?

The original engine to chassis ground strap is solidly connected. I have done the 'wiggle' test also and absolutely no difference. My TR3 is GROUNDLESS!!!!!!!!!!!!!!

Anyone remember the show "Branded" with Chuck Connors? I am singing the theme song to that but substituting the word "Groundless" in. "What do you do when you are groundless, and you know you're a man?".

Thanks to all for listening,
Jim Lee