Weird electrical problem - kills the ignition

[TR7Aaron]

I drove my '76 a bit today - no problems. I go out to move it into the garage, it fires right up but as soon as I turn on the lights, it dies immediately, like the ignition was cut off. The lights did pop up though.
I did this several times at different rpm's and everytime I turned on the lights (parking lights or all the way to headlights too), the engine died immediately.
Now, the headlights will not pop up or come on and the ignition light comes on when I try turning them on.
If I try to start the car with the light switch to 'on', everything is dead - not even a click of the starter relay. Lights off, it starts right up and runs fine.
Ideas other than the Triumph gods are angry with me?

Aaron
1976 TR7 FHC (an ongoing project)

[gaz]

put your car on a trailer and take it your nearest preist and get it exorsized (i think it might be possesed)........[;)]

It could be something as simple as a bad earth try cleaning and checking the many earth points
i once read somewhere that on someones tr7 if they apllied the brake pedal the radio would turn on, freaky

It rides again..... and again wehey!!!!!!!

[TR7Aaron]

Update:
This afternoon, the problem *seemed* to go away. I drove it about 50 miles and used the fan blower, horn, signals, brakes, etc., and NO problems. All gauges read normal.
Go to put it in the garage (same scenario - kinda weird, eh?), it starts and runs but as soon as any electrical load is put on it, it dies immediately. Brake lights, headlights, anything but the horn kills the engine. The voltage gauge reads low.
Sometimes the car will not restart for a couple minutes, other times, I have to cycle the key to off, then it *might* restart. Sometimes, if I jiggle the key while turning it, it *might* restart but I'm not sure that's related or just a coincidence. If there's any electrical load on the car when I try to start it, everything is DEAD except for the horn. No lights, no radio, nothing but the horn. Voltage gauge reads low.
Each time it dies, the ignition light comes on. Sometimes for a few seconds, sometimes the ignition light stays on.
Before I quit for the night, it got to the point where the engine would start but die as soon as I released the key - I didn't even have to turn on anything - it would start but not run.
I've checked the battery - clean tight terminals.
So, I thinking the following...
Alternator or voltage regulator fried, but the battery seems fine, gauges read OK today and how would a bad alternator or VR affect the ignition system?
Bad ignition switch? How would a bad ignition switch be related to electrical load and killing the ignition?
Bad headlight switch? If it was just the headlights that caused this, I'd investigate further but it seems to be any electrical load (except the horn) kills the ignition.
What's really frustrating is that this is not consistent. However, I'm glad now it isn't because my wife was with me this afternoon and if we would have been stranded, she would be even more mistrustful of this car than she already is.
So, any ideas?
Thanks again...

Aaron
1976 TR7 FHC (an ongoing project)

[black_1980_tr7]

does the problem happen only if the head lamps are activated or now
just any time randomly? My thoughts are a loose connection to the
ignition switch and or a fuse going bad (the a fuse filament is disconnecting itself from the end caps and becoming an open circuit...not blowing...ust falling apart from age).

You might want to check to Grounds to any ignition connected or oriented device. The ignition system may have been finding a Ground
through the head lamps or fan or blower, and if those are activated, the Ground is lost and thus the car stalls out or doesn't want to start.

[xx(]

[TR7Aaron]

There's not a lot of consistency. Sometimes, It'll fire up and run and everything works fine.
Other times, it'll fire up and run but if I turn on the lights or press the brake pedal, it dies immediately but then will start back up and be normal, other times, it will do this over and over.

The poor ground sounds plausible but I have no idea where to start since so many things seem to be causing the engine to die.

Aaron
1976 TR7 FHC (an ongoing project)

[Workshop Help]

Yes, by all means spend time cleaning the ground connections. The main ground is located next to the battery and a photo walk thru is provided in one of my articles recently.

Then, disassemble the main light switch and clean the old grease out of the switch interior. Clean the brown wire connections from the alternator to the battery. Examine and clean the fuse panel connectors located inside the glove box. Clean the other dash board switches. The ignition switch can sometimes wear out, but I cannot recommend disassembling it as the metal tabs break very easily and will result in a catastrophic failure that risks the entire car.

Your description of the symptoms indicate a short some where in the harness connectors. Given the cars age and an unknown service life, expect this kind of situation until all the electrical connections and accessories have been brought back to proper condition. Breaks in the wire itself are not unknown and it is possible an electrical short in the past has resulted in melted insulation of a hot, (Brown), wire that is contacting some metal part of the car and giving a shorting out condition.

Mildred Hargis

[cliff]

Arron, I would start by cleaning the battery terminals aqnd the main ground. A faulty ground can cause all sorts of weird symptoms leaving you right here[8][:(!]
Cliff[8D]

Don't use force, get a bigger hammer!!

[TR7Aaron]

OK, this is still happening and I'm getting really ticked off. I drove the car today - NO problems. It sat for an hour or so, I start it but as soon as I touch the brake pedal, it dies. Even if I rev it up to higher rpm's, it dies as soon as an exterior light is turned on. Also, while all this is happening, it idles very poorly - stumbling and missing. It revs up OK and is smooth at higher than idle rpm's.
As posted above, when I get it to start, if I touch the brake pedal (brake lights), shift into reverse (back up lights), use the turn signals, or turn on the headlights, it kills the ignition. The horn, radio, inside courtesy light, door buzzer, rear demister, and strangely enough, the hazard lights, have no effect. The IGNITION panel light comes on each time the engine gets killed.
I've inspected the grounds in the engine compartment and cleaned the battery terminals twice. I hooked up a voltmeter and got 12.75 - 12.95 battery voltage and when it starts, it climbs to 14+ volts, so I'm pretty sure the alternator is OK.
This may be some sort of intermittent grounding out of the ignition that may be related to heat since this has never happened when I first start using the car that day. Even with multiple starts and stops, it doesn't happen. But when the car is used, and then sits for awhile, it does.
As I posted before, if I continue to restart the engine over and over, after a few times, it stops starting and everything goes dead. Battery voltage still reads 12.5+. When I wait a little while, the fun starts all over and I will eventually get the car into the garage a few feet at a time and call it a night.
Soooo, what relationship do the exterior lights have to the ignition system that would cause them to kill the engine when warm? Could this be an ignition switch problem and if so, why wouldn't it do it all the time? Turning the wheel back and forth has no effect on whether it starts or not.
I thought I might have a battery cable problem but even without moving the cables at all, I'll turn the ignition switch 3, 4, 5 times and get nothing but it might start on the 6, 7, or 8th try, fire up immediately but then die immediately when lights are used.
It's getting to the point where I'm getting hesitant to drive the car because I'm concerned I'll get stranded and I certainly can't drive it at night.
HELP!!!!!!!!!!!!!!!!!!!!!!!!

Aaron
1976 TR7 FHC (an ongoing project)

[PeterTR7V8]

I have a similar problem in reverse. I had a towbar installed on Friday including the plug for the tail lights & on Saturday I had a couple of problems with the ignition shorting so it came on without the key. It didn't engage the starter thankfully but the warning lights lit up & the break light blinked. When I took stuff out of the boot to look at the wires it came right. It did this twice on Saturday but hasn't done it since. Putting your symptoms together with mine I suspect the brake light circuit is not right. Try disconnecting the power from the brake light switch on the brake pedal & see if that stops it.


Never say die. At least not while you're still breathing.

[TR7Aaron]

OK, here's another update...
Since my last posting, I've checked a couple times and the headlights wouldn't turn on, no response when the key was turned, nor would the brake lights work. I didn't mess with anything.
The cars been sitting a couple hours or so.
I just came back from the garage and everything seems back to normal. It fired right up, brake lights and headlights work fine and they do not kill the ignition when turned on.
THIS IS DRIVING ME NUTS!!!!!!
I'm thinking it has to be heat related.
The coil? If so, why wouldn't it fail when being driven hard?
Alternator? If the diodes heat up, they can cause havoc, but like this?
How are either of these related to exterior lighting?

After reading Peter's response above, I got to thinking - this problem began shortly after I installed my LED third brake light - could that be the cause? Once again, why this odd inconsistency that seems to be tied in to failing when the car is warmed up, yet sitting for a while?

Please, someone - throw me a bone on this. I'm really stumped and I hate to start throwing money at the car by replacing stuff until I get lucky to find what's the problem - if I get lucky.
I guess the first thing to do is disconnect the LED brakelight and see if that's the cause...

Aaron
1976 TR7 FHC (an ongoing project)

[jclay (RIP 2018)]

Let's think about this for a moment. Brakes turn it off and headlights.

The wiring that goes to the ignition switch run right past the brake peddle and the wiring for the head lights do too.

I would check the ignition switch first It is held onto the locking tumbler by two tiny screws on the sides of the tumbler at the back edge of the tumbler body, opposite the key.

Next, inspect the wiring harness that run from the ignition switch/blinker switch/wiper switch. I bet you have a loose connection but <i>you will probably find a wire that has rubbed through the insulation and is shorting out on a piece of metal under the dash</i>.

When you put on the brake, you are moving the harness with the tip of your toe and it shorts everything out. Then it will just barely sit on the short and make it run badly. Move it again and it pulls away from the metal and runs fine.

PS. Start the car and shake the wiring harness going to the steering wheel cover and see what happens. If the car dies, you know where to start looking.

jclay

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[Cobber]

<font face="Comic Sans MS"><font size="2">My money is on a bad ground somewhere.</font id="size2"></font id="Comic Sans MS">

80'Triumph TR7, , 73'Land Rover (Ford 351. V8),
'89 Ford Fairlane
85'Alfa 90, 69'Ford F250.
76' Ford F100

[Urchin]

Mildred and JClay are onto something for you; you have a significant short of one or more circuits, and you may have a secondary issue of a bad ground.

Normally, the headlights, rear lights and horn operate separately from the ignition-routed circuits; that's why they operate without the key being turned on. When you turn the ignition key, you open up other circuits. One sends power to "excite" the alternator and get it to function when the engine turns. Another sends power to the warning lamps/sender units, parking light switch position, directional signal, wipers, radio, etc.

When you hit the brake pedal, you also activate a switch that feeds the brake lamps, so any short in that circuit could feed back into your ignition key and affect other circuits.

I'd try JClay's diagnostic test.

Jeff





Jeffrey Aronson
P.O. Box 90
Vinalhaven, ME 04863
USA
'80 TR-7 Spider
'66 Land Rover Series II-A [2]
'66 Corvair Monza
www.landroverwriter.com