• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

TR6 71 TR6 Brake warning light and oil pressure light

Share this page

hondo402000

hondo402000

Darth Vader
Offline
I installed a new wiring harness in my 71 TR6 and I was wondering, when you turn the Ignition switch on are both those 2 red sockets lamps in between the spedo and tach suppose to light up and then go off when the car is running?
since before installing my new harness the hazards didnt work and neither of the 2 red sockets lamps were wired up nor did the oil pressure light in the gauge work.

now after the rewire every thing works, when I turn the Ign switch to on, the left red socket light comes on dimly( and I understand that is is suppose to be dim) and the oil pressure warning lamp in the gauge works and when I start the car both go off when the oil pressure comes up, However I cannot remember if I ever saw the brake warning lamp come on.(that would be the large red lamp on the right.

I have dan masters book and its not really clear on weather both come on or you have to do some re-wiring to get both of those big red lights to light up when you turn the ignition switch to on position.
it could be the PDWA lamp came out of the socket and not grounding
thanks
Hondo
 
Yup, both are supposed to come on. It serves as a "bulb test" function for the PDWA lamp, which was a Federal requirement.

The PDWA lamp grounds through either the PDWA, or the oil lamp. There is no ground needed at the socket (for either one).
 
That makes since, plus now that I recall those holders screw into the wood dash and not the metal portion of the dash, I hope its the bulb but they were all new when I put the new harness in. Cant believe I would already have an electrical issue to track down after only 3 months!

thanks

Hondo
 
Since the two bulbs are in series for the bulb test, they need to be reasonably close to being the same resistance/power or one will light and the other won't. It might be that all you need is to use similar bulbs in both sockets.

The resistance of incandescent bulbs goes up with usage, too. (The white-hot filament slowly evaporates and gets thinner, which increases its resistance.) So even matching a really old bulb with a new one can sometimes be a problem.

Try removing the bulb from the PDWA lamp. If the oil light goes out, then it was getting current through the PDWA bulb and your problem is mis-matched bulbs. Otherwise there is a wiring problem, perhaps a short at the PDWA lamp.
 
The red ignition lamp should be brighter than the orange OP warning lamp when the key is in the "ON" position without the engine actually running.
On that occassion the "BRAKE" light and the orange OP warning lamp are getting reduced voltage and are dim. The OP lamp and the "BRAKE" lamp will also glow dimly if there is inadequate OP while the engine is running, but the "BRAKE' light will glow brightly if the PDWA causes it to light.
 
well the bulb is ok, so now only after 3 months with a brand new wiring harness I have a problem, so now I have to pull my spedo and tach out so I can trouble shoot the wiring and find the problem, I can almost bet its in those Cheap A@@ bulb holders I also wonder if this issue is also associated with why my alternator stopped working since its in the same circuit

Hondo
 
Back
Top