Rear Side Light - Safe, Legal Fix?

[Maxwell]

Guys - and Mildred!

Today I noticed my rear side light was not working.
Right Hand Drive car, Near-side problem.
Investigation showed a blackened bulb.
However, the new bulb wouldn't work, neither would the 'good' off-side one when the holders were swapped over.
The power supply was checked, and it was found that there's no leccy coming through the red wire that emerges from the loom on the near-side. And here's me thinking it was a bad earth!

I've temporarily jury-rigged a new supply to the near-side, taking power from the off-side bulb-holder terminal, and it works.

A safe fix, or should I hunt down the original fault?

Thanks Guys.. Maxwell [;)][8)]


2.0 TR7 FHC \ Current
1.8 Mazda MX5 \ Current

[Workshop Help]

'Guys - and Mildred!'? We'll leave this topic for another time.

On to the excitement, with bugles blaring and cannon roaring!

In reviewing the official wiring diagram for my 1976 Federal model car, it is observed the red wire providing the current to the side marker lamps is fed thru a connector from the license plate illumination lamp. Working our way back, the red power wire is fed thru a 25 amp fuse.

Has the fuse been verified to still be intact?

Have you cleaned the corrosion from the license plate light red wire connector yet?

Have you brought a box of donuts for everyone in the class to share?

Mildred Hargis

[Maxwell]

Hi Mildred - and thank you for your quick response!

It's NOT the side marker light, my car has none of these fitted.
It is the a part of the rear-lamp cluster, along with the reversing lights and the indicators. It comes on with the front side-lights [First stop of the dashboard switch]

The red wire that powers it is six\nine inches long and disappears into a 'flat-ribbon' loom. I have checked the earth, but the red wire is dead \ and has no power, unlike the off-side one.

Any idea where the other end of the wire is? Perhaps I should check there! I guess both rear lights would be covered by a single fuse rather than having one each? The off-side light still works...

Donuts are still at the bakers.....

Maxwell [:(]


2.0 TR7 FHC \ Current
1.8 Mazda MX5 \ Current

[saabfast]

Andrew
Does the corresponding front side light work? I seem to remember mine had a fuse for each side (also just checked the wiring diagram). I had problems with the fuse needing a clean one year, got a bit of damp corrosion in it at the contact. A quick clean-up of the fuse ends sorted it.-

Alan
Saab 9000 Stg 1 (now passed to son for his family car)
Saab 9000 2.3 FPT Auto (now gone that others might live)
Saab 9000 2.3 LPT Auto (sold on, wish I had it back)
Saab 9-5 2.3 Vector Auto Estate
'81 TR7 DHC

[Maxwell]

Hi Alan - Yes, both front side-lights work. Just been out in the rain to check...

Maxwell [xx(]


2.0 TR7 FHC \ Current
1.8 Mazda MX5 \ Current

[saabfast]

The wiring diagram shows the power from the switch as a single feed to the fuses (o/s and n/s), then the feed to each side splits to front and rear. As the ribbon cable runs under the carpet I would think the junction is just after the fuse box. The problem may be damage to the ribbon cable - has there been any work around the floor, (like the welding you had done), or anything damaged the wire in the boot?

Alan
Saab 9000 Stg 1 (now passed to son for his family car)
Saab 9000 2.3 FPT Auto (now gone that others might live)
Saab 9000 2.3 LPT Auto (sold on, wish I had it back)
Saab 9-5 2.3 Vector Auto Estate
'81 TR7 DHC

[Maxwell]

A Mystery, Alan. No welding, and nothing in the boot that could have damaged the ribbon. It has been OK, so I don't know what's changed to break the wire. For now I'll jury-rig another wire from the off-side bulb holder and carry a few spare fuses in case one blows, then I'll see about getting another wire run from the fuse box to the back....
Owning an old car isn't always fun!

Maxwell [|)]


2.0 TR7 FHC \ Current
1.8 Mazda MX5 \ Current

[Workshop Help]

Dearest Maxwell, it seems we are using different versions of the Queen's English here. Near side, off side, rear side; for I all know we may be referring to the bottom side of the car.

Are we talking about the lights clustered in the common housing at the back of the car? As in the brake lights, and the back-up lights, and the turn signal lights, and the lights we turn on along with the headlights? It now seems so from the further posts.

Pray tell, have you the wiring diagram for your model car? Do you see the connectors to each of the lighting housings? In my 1976 model year, U.S. Federal model wiring diagram, the tail lights are shown as '33' on the diagram. They are joined via a connector to the red wire from the license plate lamps which then goes upstream to the 25 amp fuse.

Rereading your initial complaint, I now ponder the condition of the original bulb holder, as well as the possibility of corrosion in the red wire connector(s).

Mildred Hargis

[Maxwell]

Hi Mildred..

Yes, we are talking about the lights clustered in the common housing at the back of the car. Brake lights, the turn signal lights and the lights that turn on along with the headlights.

I do have a wiring diagram for the car but not been able to look yet.
I have a canvas garage with no lighting, and very little space to work! The condition of the bulb holder looks to be good, and I've also tried using two spare holders that I have as well. I've also swapped the 'working' one from the other side, to no avail.
The red wire, when tested, appears to have no power, so either there's corrosion in the spade-connector that I cannot see, or a broken wire somewhere. There's only six inches of wire from the bulb-holder to the ribbon-loom, and it goes nowhere near the license plate!

Maxwell [xx(][:(]



2.0 TR7 FHC \ Current
1.8 Mazda MX5 \ Current

[REPLIC8]

Hi Maxwell
Looking at my wiring diagram there is a 15 amp fuse which powers the N/S front sidelight, the N/S rear taillight, both number plate lights & the interior lights. If all the other lights on this list are working OK and only the taillight is out, then I would think the connector to the bulb holder has a break in it. Try cutting the wire back about 10mm and put on a new spade connector. [:)]



Andy
1981 TR7 FHC

[johnny5]

Hi Maxwell

My wire harness is currently not fitted to my car so it been easy for me to trace were the red wire goes. It goes to a 2 pin connector I labelled L/H boot lid harness. I'm guessing this supply's power to the number plate lights. This connector as 2 red wires spliced together and 2 black wires, the other red wire travels down the harness to the fuse box

If your number plate lights are working then its a good bet there's a brake in the cable between this connector and the L/H rear light.

A method I use to check brakes in cables is to push a needle through the insulator of the cable and use a multi meter to check for continuity. It Could save cutting off what might be a good connector.

John

80 DHC Green
77 FHC White

[Maxwell]

Hi John - Thanks for that. Just discovered that the number plate lights are out as well, but everything else works. I'll check further when I get back home!

Maxwell


2.0 TR7 FHC \ Current
1.8 Mazda MX5 \ Current