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Tech Spam thread - because 1/4" BSP gets 5 hand spans to the jiggawatt


Roman

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Your 5w bulb is about 30ohm and needs just under half an amp to run. Whatever transistor in the ecu possibly had a bit of leakage (or some other source where ideally it shouldn't be coming from) which isn't enough to light the bulb but as the led will glow with a couple of milliamps, the current would still flow through the conventional bulb largely unhindered. The resistor across the led should allow it to effectively flow past the led instead of through it, untill it is supplied the full switched power.

At least that's the theory in my mind. There's people here far more knowledgeable on this subject than I so I'll shut up now.

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Sounds like a good solution, probably going to need more than my basic solder skills to tie into it as the points in the cluster are microscopic. 

 

does a measurement of .4 micro amps current in that circuit seem right?

 

Could this be from an earth in an adjacent cable? As the circuit is constant +ve and earth switched?

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3 hours ago, Transom said:

Fuel pressure gauge ... Install on high pressure feed line or on return line after regulator ? Or does it make no difference ? 

Seems te aftermarket fuel pressure regs have them on the reg so that's after injectors ... Any thoughts ? 

The pressure gauge will be on the injector side of the regulator :-)

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14 hours ago, chris r said:

Just stick a bulb in series lol

Yeah nah tried that.

 

i need to put a 20 ohm resistor into the fuel sender and 80 ohm into the temp gauge to get them reading where i want them, so if i can surgery the 300 ohm as suggested in parallel with the led then i will do that.

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I used to chip xboxes and Playstations a while ago and I ground up the tip on a soldering iron to get onto the small spots.

You might have to carefully scrape off the lacquer before you can get it to stick.

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On 2017-6-24 at 15:35, Firetruck said:

 

Your 5w bulb is about 30ohm and needs just under half an amp to run. Whatever transistor in the ecu possibly had a bit of leakage (or some other source where ideally it shouldn't be coming from) which isn't enough to light the bulb but as the led will glow with a couple of milliamps, the current would still flow through the conventional bulb largely unhindered. The resistor across the led should allow it to effectively flow past the led instead of through it, untill it is supplied the full switched power.

At least that's the theory in my mind. There's people here far more knowledgeable on this subject than I so I'll shut up now.

You're probably correct, but you may still need a series R too, because an LED is typically a 1.2V (red) to 4V (white) device.

This could be built into the LED enclosure if it's a 12V item

So @mjrstar 

|-------- 2000ohm -------|

| --------- LED --------------|----------- 500 ohm ----------- CEL

 

 

Tweak values for bypass ( less to reduce off glow) and feed (less for more 'on time' brightness)

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