landrover598 Posted March 26, 2008 Share Posted March 26, 2008 Can any of you electically minded people give me some help I need to wire in an ignition warning light to 200TDi (not useing an original dash) I have a small wire coming off the back of the alternator, and a warning light with two terminals on the new dash. Any ideas which way things need to be connected ?? I've looked at a TDi wiring diagram but keep going in circles Also there's something about a resistor in the circuit Cheers Quote Link to comment Share on other sites More sharing options...
TSD Posted March 26, 2008 Share Posted March 26, 2008 Can any of you electically minded people give me some help I need to wire in an ignition warning light to 200TDi (not useing an original dash) I have a small wire coming off the back of the alternator, and a warning light with two terminals on the new dash. Any ideas which way things need to be connected ?? I've looked at a TDi wiring diagram but keep going in circles Also there's something about a resistor in the circuit Cheers One side of the bulb goes to the alternator wire, and the other side to ignition switched 12V. There's two places a resistor might be used, not sure which one was done :- Either in parallel with the bulb to provide additional current to the alternator if the bulb wattage is too low, or from the alternator wire to ground to provide a fail-safe warning (warning light if the wiring is boken or the regulator fails). Most likely it's the first one, but you can try without either. If the light doesn't go out until you rev the engine a bit, you need the resistor in parallel with the bulb. Quote Link to comment Share on other sites More sharing options...
TSD Posted March 26, 2008 Share Posted March 26, 2008 Got curious so had a squint at the circuit diagram (300 Disco - first one that came to hand). The only resistor I found is the one labelled 'Phase Tap Resistor' which is used to drive a rev counter, not the warning lamp. Worth checking, your small wire should come from the D+ terminal, not the W terminal. Quote Link to comment Share on other sites More sharing options...
landrover598 Posted March 26, 2008 Author Share Posted March 26, 2008 One side of the bulb goes to the alternator wire, and the other side to ignition switched 12V. Cheers. I tried it without the resistor, and the light goes out almost straight away. Quote Link to comment Share on other sites More sharing options...
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