LED Dash Light Problem

[Westfaling]

I've converted the dash lights to LEDS following a path travelled before and a parts list that Martin supplied. All seems to work well with the dash out. When I apply 12 volts to the red and pink wire that fed power to the rheostat. Lights come on. I've removed the rheostat and wired the red/pink wire to the red/white wires that feed the gauge lights. I assume that makes sense?
When installed, the 10amp fuse (fuse 7-8 or fourth one from the end) blows each time I turn on the side lights. I unplugged the multi pin connector to the instrument cluster and the problem goes away.
My multimeter indicates no continuity between red/pink and black at the multi pin connector serving the dash lights. Is that a quirk of the LEDs?
While writing this I've realized that there is a back feed from the dash to feed the fag lighter illumination. It occurs to me That I may have got this screwed up.
Any other suggestions???
Nick

[V Mad]

Nick, yes that is a quirk of LEDs when using a multimeter which only has a 1.5 volt internal test battery. Current will not pass through an LED at 1.5 V (they need at least 2 to 3 volts.

When the dash was out were you applying 12V directly to the LEDs? I assume they are 12V LEDs and therefore have an inbuilt resistor or other circuit to control the current. If that is the case then fitting the dash must be shorting something out; you might have grounded the live side of the LED wiring?

[Westfaling]

Chris
Thanks and well done getting the Stag on the road. All the bench tests I did feeding 12V to the harness plug worked fine.
I'm now thinking that the feed back to the centre console must have a short in it. Something to check tomorrow.
Nick

[ukbiggles]

Hi Nick

If it helps, I went down the 'Martin parts route' too and all is well. Gauges are back in the car and all working just fine - and much better than the glow worms that were there previously, though I did paint the inside of the speedo and tacho gloss white to improve things too. I think the option to put led strips inside the gauges may be even better, but Martin's approach is simpler, and good enough for me. I don't use the car much in the dark anyway.

Cheers

Gord

[KOY 23]

Nick.
sounds like the LED wiring is fine and you have a short elsewhere. Suggest you fit a couple of leads with croc clips to a headlamp bulb and connect this across the fuse. It will shine a full brightness if you have a short, you can then isolate circuits until the lamp goes out. Will save you a lot of fuses.

You can also use the bulb to measure supply to fuel pumps etc, as it will load the circuit and show any high resistance connections, which a high impedance multimeter will not.

John.

[milothedog]

Nick.
sounds like the LED wiring is fine and you have a short elsewhere. Suggest you fit a couple of leads with croc clips to a headlamp bulb and connect this across the fuse. It will shine a full brightness if you have a short, you can then isolate circuits until the lamp goes out. Will save you a lot of fuses.

You can also use the bulb to measure supply to fuel pumps etc, as it will load the circuit and show any high resistance connections, which a high impedance multimeter will not.

John.

Blonde moment answered my own question

Ian

[KOY 23]

Damm. too late

[Bob Heritage]

I've converted the dash lights to LEDS following a path travelled before and a parts list that Martin supplied. All seems to work well with the dash out. When I apply 12 volts to the red and pink wire that fed power to the rheostat. Lights come on. I've removed the rheostat and wired the red/pink wire to the red/white wires that feed the gauge lights. I assume that makes sense?
When installed, the 10amp fuse (fuse 7-8 or fourth one from the end) blows each time I turn on the side lights. I unplugged the multi pin connector to the instrument cluster and the problem goes away.
My multimeter indicates no continuity between red/pink and black at the multi pin connector serving the dash lights. Is that a quirk of the LEDs?
While writing this I've realized that there is a back feed from the dash to feed the fag lighter illumination. It occurs to me That I may have got this screwed up.
Any other suggestions???
Nick

Could this be your problem? black being neg.

[Westfaling]

John
Good idea thanks I'm running low on 10 amp fuses. I have bought Chris' blade fuse box conversion but I though I'd trouble shoot the wiring before adding another variable by changing the fuse box.
Bob
I was measuring across the multi pin connector as the instruments ground/ earth through the connector. I guess the wood dash doesn't offer another path back to the neg terminal on the battery.
Nick

[Westfaling]

Anyone know what/ where the heater control light might be? Item 35 on the wiring diagram for my car.
Nick

[Westfaling]

Found it!!
Almost ran out of ideas but rechecked the ROM and noticed that the auto gear shift light was on the same circuit. So with dashboard already out it wasn't a big step to pull the centre console apart. Sure enough the red/white wire was grounded ( by me) to the ground wire. Why had I done this you might ask. Well I'd tagged the wires as Auto Inhibitor Switch ( which I no longer needed having converted to manual so I'd connected the two wires together.
A second look at the ROM revealed that the Auto Inhibitor switch wiring was white/ red hence my mistake.
Despite the frustration and the time taken (probably 4-5 hours) it's really satisfying to find and fix things yourself.
Nick

[jleyton]

Anyone know what/ where the heater control light might be? Item 35 on the wiring diagram for my car.
Nick

On some LHD models (possibly only american ?) there was a large black shroud that was fixed above the heater controls which shone a light down on them. It looked like a very poor Harry Moss aftermarket fitment

I guess this is what your diagram refers to.

Cheers

Julian