Do Rheostats catch fire?

[bottomtop]

When driving with my headlights on for 10 minutes or so, I noticed an electrical smell that scared me. The plastic around the Rheostat was also a bit too warm for my liking, and the smell seemed to be coming from there. Off with the lights. Funny thing is I don't get the heat with the parkers, only the headlights, but both turn on the dash lights.

I intend to get rid of it and bypass until I can get a replacement. Are there other things that I ought to check while I am at it?

[Henk]

Set the rheostat in in full position or make a bypass, then there is no resistance and of course no smell.
btw did you has the heater on?
But it appears me more that it has to make with the headlights.
Because the headlights and parkers would not become connected via the rheostat I think it is more likely the light-switch.

Henk

1980 TR7 US Convertible
1978 Mini Clubman Estate

[Hasbeen]

Check the connecter your headlight switch plugs into.

I have had trouble with a couple of these, due to corrosion in the
plug.

The headlight switch itself can also get very hot, & probably burn.

Hasbeen

[Beans]

It really doesn't make sense ... [8)]
First check for strange wires or connections behind the centre console. Maybe a wire got jammed between radio and dash panel [?]
After that dismantle and check the light switch. Clean thoroughly and use a little contact grease on the contacts.

As often happens with these old cars is that lots of PO's have bodged the wiring over the years. I ripped out the complete wirirng from both roadgoing cars before I put them into use. I know a lot of work, but then I don't often have preblems with the electrics.

<center>
<font color="blue"><i>1981 TR7 FHC Sprint (better known as 't Kreng)
1981 TR7 DHC (not very well known yet, but back on the road)
Also a 1980 TR7 DHC, 1980 TR7 DHC FI, 1981 TR7 FHC
http://tr7beans.blogspot.com/</i></font id="blue"></center>

[bmcecosse]

Headlight switches are infamous for failing - as are the main/dip stalk contacts. If the smell is only there with headlamps - then the rheostat is just a red herring!

[FI Spyder]

I agree with bmcecosse. Full headlight power (lots) goes through headlight switch (lots). If switch has higher than normal resistance it could heat up. I would be concerned with what has been bodged under the dash/console. Yes it is a hassle to take off dash and check and clean all contacts/switches involved. These cars are 26plus years old, often parked out in the weather and the contacts for the most part are not sealed. It needs to be done if you want reliable electrics. As Beans said do this and you will have few electrical problems. (good winter project if you have a garage.)

Not that much power is going through rheostat and if something else is not screwed up it should not heat up.

TR7 Spider - 1978 Spifire - 1976 Spitfire - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra

[Beans]

Good thing about the headlight switch is that you can dismantle them for cleaning etc. Never had a failure in almost 20 years of TR7 ownership. And my head lights do get used.

<center>
<font color="blue"><i>1981 TR7 FHC Sprint (better known as 't Kreng)
1981 TR7 DHC (not very well known yet, but back on the road)
Also a 1980 TR7 DHC, 1980 TR7 DHC FI, 1981 TR7 FHC
http://tr7beans.blogspot.com/</i></font id="blue"></center>

[Hasbeen]

May be its a factor of our damp, warm climate, but my last headlight
switch lasted just 46 kilometers, about 35 minutes. The one before
lasted 3 nights, about 2 hours.

The little white plastic pins that move the brass strip get too hot,
& deform, in the new switches, & this is after the my auto
electrician said everything was OK.
It now seems OK now, after relaying the circuit.

On this car had the plug for the switch had been so hot it was
chared, & I had to find a replacemrnt.

So Beans, hang onto your old switch, the replacement ones are cr4p.

At least the pins are replaceable. If mine fail again, I will
machine some up, out of a high heat acetal.

Hasneen.

[Beans]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Hasbeen</i>

...So Beans, hang onto your old switch, the replacement ones are cr4p.<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
I'll do that, have a fair bit of them lying around.
But I am putting other (heavy duty) toggle switches in 't Kreng though...



Just trial fitting, have to adapt one of the wiring looms to get it connected properly [8D]

<center>
<font color="blue"><i>1981 TR7 FHC Sprint (better known as 't Kreng)
1981 TR7 DHC (not very well known yet, but back on the road)
Also a 1980 TR7 DHC, 1980 TR7 DHC FI, 1981 TR7 FHC
http://tr7beans.blogspot.com/</i></font id="blue"></center>

[Rich in Vancouver]

I know that this has been covered before, but it would be good info to add to this thread.
Is there an easy to install kit made to add relays to the headlight circuits?
OR; Can anyone point the way to a simple wiring diagram to carry out the job using parts store components?

Cheers,
Richard

1975 TR7 ACL764U

[Odd]

It's not that easy that anyone should just try to do it [fitting relays into the headlamp cirquit]
but it's a good thing for the switch if it's done...
As an EE I'd recommend anyone [who can't figure this out for themselves from the normal
schematics in the ROM] to get your friendly local auto electrician to do it for you.
Money well spent imho...

[FI Spyder]

You can get a headlight relay kit for under $40 from Vitoria British that is reported to be easy to install. Good for standard lights, a must for going the halogen route.

I recuse myself from the difficulty issue as I have been trained in years past on the IBM Copier ModelI which has the miles of wiring and realays and contacts reputed to rival the Boeing 747. [:D]


TR7 Spider - 1978 Spifire - 1976 Spitfire - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra

[bottomtop]

Thanks for the replies. I will investigate the switch. I see replacement switches are in the Rimmer's catalogue, but based on your experiences it would be better to repair/clean the original (if possible) than order a replacement?

[Jolyon39]

Hi,

Some of you say that adding a Relay to the headlights is a little tricky and not for the inexperienced people. I am planning to do this so can you tell me if I am on the right track.

Plan:

1. Add a relay box from Subaru to the passenger side inner Guard/Fender. (About 6 or 8 relays in the box plus fusable link)
2. Add power from battery +ve directly to this relay set up using a heavy cable
3. Cut into headlight loom and connect headlight side of of loom to the power/battery side of the relays.
4. Connect the light switch end of the loom to the low power side of relay to switch the high power side.

There are some earth issues and just working out which connector on the relay is high current and which is low current. If this works then the air con will get changed and the planned electric fans will be connected through this set up.

For aethetics I plan to hide as much cable as possible inside the guard/Fender assembly.

Does this work in principle?
Will the headlight switch now only draw low current as the switch side of the relay only needs low current?

Thanks

Jolyon

[Hasbeen]

Yes Bottom, hang onto your old switch, the new ones are suspect.
Also very expensive, here in Oz.
I paid over $90 for them here, & the relay job, fitting & parts was
only $60.

Jolyon, it looked pretty simple, WHEN THE AUTO ELECTRICIAN DID IT,
on mine. I'm sure I could stuff it up realy easily.

Hasbeen