Todays electrical challenge

[TRclassic3]

Looking for some advice on how to diagnose this problem. Car is a TVR 2500M, but just think of it as a TR6 in wolf's clothing. So here are the symptoms

With the hazard switch unplugged the turn signals work correctly, right and left, but blink faster than normal.

With the hazard switch plugged in, the 4 way work perfectly, but the turn signals will also blink all 4 corners when activated. This is regardless of whether right or left is triggered and with the hazard switch off.

I have ordered new flashers just to remove that from the mix.

Does this sound like a bad ground somewhere? Any suggestions on how to find the problem?

TIA

 

[Andrew Mace]

I don't know how the TVR wiring might differ from that of a Triumph, but my first thought is that the hazard switch is miswired or has some sort of internal fault. However, your thought of a bad ground is a possibility; I'd first make sure all four signal lamps are getting good ground.

 

[TR3driver]

The fast blinking might indicate a wrong flasher, but more likely a bulb installed wrong or a bad ground.

But the problem with the hazard switch almost has to be with the switch itself. With the switch off, it should not be connecting the GR and GW wires together, but clearly it is since things work normally with it unplugged.

I don't know what your original flasher switch looks like, but electrically you can substitute an ordinary DPST or DPDT switch. Might be worthwhile just for testing, even if you want to search out an original switch. Here's an example:
https://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=120692510031&viewitem=

BTW, I found a diagram at https://homepage.mac.com/farquasi/TVRCCNA/Tech/pdf/Mod2500MWires.pdf that might be a good starting point for mapping out your own car's wiring.

 

[TRclassic3]

Andy and Randall

Thanks for the input. As both of you reference the switch, it would seem the place to start. The switch is new, as the one in the car when acquired was kaput. So, hopefully the switch is ok internally. What comes into question then is the possibility that I did not connect the new switch correctly. I suspect that at the time I replaced the switch, that I assumed I had it right as the hazard warning appeared to work OK.

I already have that wiring diagram (thanks for researching it) and, although not completely accurate, it is my starting point for my quests into the wiring.

Thanks again

 

[hondo402000]

what year car would be the first question, does the hazard switch have 4 prongs?
I just went thru that scenario on my 71 TR6, my hazard switch was bad and the hazard flasher too, as far as wiring, on my 71 TR6 light green/brown and light green brown go on the top two terminals, purple, purple red on the bottom two terminals

I figure the wire colors should be in pairs, see if you have the wires on the switch correctly, the turn signals will not work unless the switch makes contact in the non hazard position and the key has to be on, with the switch in the hazard position the hazards will flash with the key off on in acc position

hope this helps, it only took me about 1 week, 200.00 hazard switch, and a 7 dollar hazard flasher, oooo and a new relay which is round and blue now. But every thing works now, did I mention the new front wiring harness too

Hondo

 

[hondo402000]

ok when am I going to be upgraded from Jedi Knight!!!!! Maybe Lucas Night!

 

[TRclassic3]

Hondo,

Thanks for the response. The connector for the 4 way is orginal and has the 4 wires. I even think the color coding is the same as you mention. The new switch has 6 prongs actually. 4 are in the top 4 positions and line up correctly with the connector. The other 2 are at the bottom of the switch. Because the hazard lights function correctly, I assumed the the switch and the mating of the connector to it were correct. Now there's seems to be a question with regard to that. Unsure how to proceed. The hazards will work with the ignition switch off, and the ingniton needs to be on for the turn signals to work. So, that all seems to be as it should.

I must say, it doesn't help that TVR used ALL black wire.
Makes tracing a bit of a challenge. They used little colored collars at the ends of the wires. These now all appear to be various shades of brown. Fun stuff

 

[DNK]

The new switch has a different wiring and you will need to look at the 72 model TR6 year for that .
Hondo just bought the 4 prong which are available again from Moss albeit 2 kidneys needed .

 

[TR3driver]

There are lots of different ways of arranging the hazard flasher circuit; I'm pretty sure that Ed's 77 TVR is different than Hondo's 71 TR6.

Ed, if your car follows the diagram I referenced above, then for the hazards to work, the switch only has to connect all 4 wires together. But for the turn signals to work properly when the hazard switch is off, the two output terminals must be isolated from each other and from the two input terminals. Although it sounds like you have the wrong new switch, it can probably be made to work if you can identify the switch terminals, the wires involved, and make the appropriate connections between the two.

Pull the connector off the switch, and probe all 4 wires with a voltmeter or unpowered test light (other side grounded). You should find power on 2 wires. Mark those as "from flasher".
Now turn the ignition and left turn signal on and probe the remaining wires, remaining on each one long enough for the turn signals to cycle. You should find one wire that 'flashes' along with the turn signals. Mark it as "left turn" (or GR if you want to follow the standard color codes).
Turn the right turn signal on, find the wire for "right turn" or GW.

Now to the switch. Turn it off and try all possible pairs of terminals with an ohmmeter or continuity tester. I'm guessing that you will find two pairs of terminals that are connected. Temporarily mark them as "pair 1" and "pair 2". Now turn the switch on and repeat the process. Again, I'm guessing you will find two pairs of terminals that are connected together. Mark them as "pair A" and "pair B".

If I have guessed correctly, there will be two terminals that are always connected to another terminal. Connect the "from flasher" wires to those two terminals (doesn't matter which is which). Now you will have one terminal left open from "pair A" and one terminal from "pair B". Connect the GR and GW wires to those two terminals (doesn't matter which is which). That should make it work.

If the switch doesn't match what I have guessed, post your findings back here and we'll work something out.

 

[TRclassic3]

Randall

I followed your suggestion and I'm afraid the mystery deepens (at least for me). Here are the results (rechecked 3 times to be certain.

First the plug. Four wires, we'll call them P1, P2, P3, and P4. Only P2 is hot all the time. P3 is hot on right turn and P4 for left turn. P1 never appeared to have juice

Switch with 4 posts S1, S2, S3 and S4. Only S3 and S4 have continuity as a pair in the off position. In the On position every post has continuity with every other post. Every combination!

Can we make any sense of this?

Thanks
Ed

 

[TRclassic3]

Randall

After again reading your hypothesis, I'm wondering if swapping P1 with either P3 or P4 might do the trick. I'm suggesting that the problem is that P3 and P4 have continuity in the off position and should not. Am I even close?

 

[Twosheds]

Looks like P2 comes from the flasher. It should connect to S3 and S4. Should be a jumper between P2 and P1.

P3 - S1 and P4 - S2 or the other way around to get the left and right turn signals to flash correctly.

 

[TR3driver]

John has the right idea, but it doesn't sound as though the jumper is necessary.

So, P1 and P2 need to go to S3 and S4 (by that I mean that either P1-S3, P2-S4 or P1-S4 and P2-S3 will work fine).

Then P3 and P4 need to go to S1 and S2 (again doesn't matter which is which).

IOW, the plug is upside down.

 

[TRclassic3]

Did a quick test by plugging "upside down". As suggested, the hazards go on as expected, and the turns work correctly, no longer flashing all 4 at once. The only odditiy that occured with this arrangement is that the 4 way indicatior light is lit continuous except when the 4 way is swithced on. It then flashes as it should.

 

[TR3driver]

Any idea how your hazard indicator is actually wired?

The "modified" diagram I linked to above shows it wired to the 3rd pin on the flasher. If that is how it's wired, then most likely you have an incompatible flasher. I have seen the same problem with the turn signals on my TR3A, the 3-terminal thermal flasher at FLAPS would leave the indicator on, even though it was supposed to be a replacement for the original flasher. I found that a Tridon EL-13 "electronic" flasher solved the problem.

However as I recall, the 'original' for the diagram above showed the indicator lamp connected differently. I can't seem to find it again at the moment, but I recall thinking "that won't work".

 

[TRclassic3]

This is the one I go by. It is far closer to what I have than the Modified.

https://homepage.mac.com/farquasi/TVRCCNA/Tech/pdf/NewWiringDig.pdf

 

[TR3driver]

So is your hazard flasher a 2-prong flasher then?

According to that diagram, the hazard indicator light should stay on all the time. The flasher has to supply 12v to it's output, so it can know when the switch is closed and start flashing. That diagram shows the light wired directly from the flasher output to ground. So it will either flash, or be on all the time.

 

[TRclassic3]

It's 3 pronged Randall. I thought the diagram made it look as though the light would be on all the time except when flashing. That seems a bit fishy. Can you see a reaason why it would not be on all the time with the "original" configuration, but would be "upside down"?

 

[TR3driver]

If it is a 3-prong flasher, then almost certainly the "original" diagram is wrong in that area. The third prong is strictly for operating the dash light, and there would be no sense in using a 3-terminal flasher if the third pin was not going to be used.

 

[Twosheds]

John has the right idea, but it doesn't sound as though the jumper is necessary.

Glad it works now!

I agree with The Randall; a jumper is not needed. I couldn't tell from the wiring diagram if they were showing a jumper there or an internal connecton in the switch. From Ed's continuity check, they are apparently showing an internal connection.

Maybe they are increasing the current-carrying capacity of the switch by using both poles?