74 2500M: annoying electric gremlin

[Renaldo]

Guys, no doubt previous owners have messed with my M's wiring, so it's a bit of hodge podge. And I'm very far from confident dealing with electrical issues.

For no quickly discernable reason, suddenly my seat belt buzzer has been sounding on its own, unrelated to any seat belt wearing. The buzzer has never worked before.

And only when the car is in gear. No buzzing when it's in neutral.

For now, all I want to do is disconnect that annoying buzzer.

Can any of you electrical experts offer me a quick fix or any advice?

Ron

[GadgeS3C]

I'm no expert (!) but I've not heard of a seat belt warning buzzer fitted to the M series this side (UK) of the pond.

Just checked the US spec wiring diagram and I can't see it on there - http://www.tvrccna.org/tvrccna.pl?page=technical - see 2500M wiring diagram.

Are you sure it's a seat belt buzzer - you mention it's not related to seat belt wearing?

If you can find where the buzzer is then I'd just disconnect the wires to it, hopefully the sound will lead you to it.

Might be worth checking it's not a "this car about to self-destruct" buzzer though

[Renaldo]

Gary, thanks for weighing in. The really baffling part is that the damn buzzer only sounds when the car is in gear.

I'm guessing it's a seat-belt warning buzzer, because I don't know what other electric warning buzzer would exist in a car that old.

But I think you're right: find the stupid buzzer and disconnect it. It's behind the dash somewhere.

And pray the whole lot doesn't go up in flames...

Ron

[GadgeS3C]

Ron,

Couple more thoughts - if it is a seat belt buzzer then they'll be wiring from the seat belt buckle. Can you see any wires running to it?

Surprised it's only if in gear too - wouldn't have expected it to have a neutral sensor. Sounds like a very high tech 2500M!

Hope this helps,
Gary

[Renaldo]

Well, found the "buzzer" and pulled off the ground wire, so no more buzzing. (a blessed relief)

However, things are still not right. Along with the buzzing, my top left dash light (red in my car) comes on, when I shift into gear (I think that's the light for the rear window demister). No light when in neutral.

Fuel gauge not working either. All other electrics seem ok.

An enigma, wrapped in a riddle, encased in a mystery.

Any educated guesses or advice? Sell the car perhaps?

Ron

[Adrian@]

Rear earth....this a ground that is wired in front of the tank (inside the car),BUT is earth out, via a anti rattle washer on the external 3/8 nut on the rear most body mount.
Adrian@

[ATE399J]

Adrian@ said:

Rear earth....this a ground that is wired in front of the tank (inside the car),BUT is earth out, via a anti rattle washer on the external 3/8 nut on the rear most body mount.
Adrian@

Yup.... It's a plastic car, earths are always the place to start!

[Renaldo]

Thanks guys. Here's what I found when I removed the rear "parcel shelf" panelling to get a look at the gas tank area:

sending unit wire was plugged in, but a black wire with a ring terminal on it is unattached to anything. Popped or worked loose maybe?

I'm thinking this is the ground wire referred to. Now I only have to figure out where I need to attach it for a proper ground.

Can anyone give some tips about finding that proper attachment point?

Ron

[RCK974X]

If all else fails, connect it to a bolt which fastens through to the chassis.....

The fuel tank is probably earthed, as long as fuel gauge behaves as expected, as are the rear lights, as long as they are reasonably bright.

[Adrian@]

Rear earth....this a ground that is wired in front of the tank (TVR part number 10356 plate body anchorage WITH earthing strap pin which is inside the car),BUT is earth out, via a anti rattle washer on the external 3/8 nut on the rear most body mount.
Adrian@
Note on early cars the rubber body mounting on this would of been metal oblong plates (as required) so that the earth body anchorage was a 'solid' fixing, the rubber allows the earth connection to fail over time.

[thegamekeeper]

rear Earth to ground control, rear Earth to ground control. Can you hear me Major Tom?


What on earth (pun) is an earth out and while you,re at it what is an earth in? They sound like bus stops for the Space Shuttle. Its not rocket science, its a bad earth on a TVR. Keep your feet on the ground Adrian!

[Renaldo]

Thanks guys. I'm on the case. I'll report back with my results (success, I hope).

Ron

[pridaux]

thegamekeeper said:

rear Earth to ground control, rear Earth to ground control. Can you hear me Major Tom?


What on earth (pun) is an earth out and while you,re at it what is an earth in? They sound like bus stops for the Space Shuttle. Its not rocket science, its a bad earth on a TVR. Keep your feet on the ground Adrian!

Earth to Adrian Earth to Adrian we understand what you mean an earth in is point inside that goes to an earthing point inside our spaceship where a number of various items gather up all that earthy goodness inside such as rear lights that without we would be stuck in outerspace with no way to get back to earth.
A

[Renaldo]

Guys, I attached that black wire with the ring connector to one of the metal fuel tank straps. Couldn't see another clear-cut attachment point.

No luck. Fuel gauge still defunct. But red dash-light no longer glowing and seat-belt buzzer silent!

I'm sure you're right: it's a bad ground somewhere. Behind the dash perhaps?

Latest odd symptom: turn signal dash light flow faintly, when headlights turned on.

Any more suggestions about how to get to the solution?

Ron

[thegamekeeper]

pridaux said:

Earth to Adrian Earth to Adrian we understand what you mean an earth in is point inside that goes to an earthing point inside our spaceship where a number of various items gather up all that earthy goodness inside such as rear lights that without we would be stuck in outerspace with no way to get back to earth.
A

Please God

[pridaux]

thegamekeeper said:

Please God

Glad to see you have taken up the faith keep praying and your prayers may be answered
A

Edited by pridaux on Friday 9th August 19:02

[thegamekeeper]

pridaux said:

Glad to see you have taken up the faith keep praying and you prayers may be answered
A

Promise!

[thegamekeeper]

So you do a one way space trip and I get Venezualan beach babes. Jesus. Result

[pridaux]

thegamekeeper said:

So you do a one way space trip and I get Venezualan beach babes. Jesus. Result

LOL

[ATE399J]

I think the tank straps may not be earthed. Just as a test, you could try runnning a wire directly to the battery neg from your "earth" point in the back and see if that does the trick.