Engine starts but no signal to the dash?
#5
Boost Pope
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Depends on year of car.
'90 to '93 there's a yellow/blue wire going from the igniter to the tach and diagnostic box.
'94-'95.5 (cars with four wire coils) the wire is black/white and comes off both coils in parallel.
'95.5-'97 the black/white wire comes from the ECU.
'99-'05 it's a green/orange wire from the ECU.
'90 to '93 there's a yellow/blue wire going from the igniter to the tach and diagnostic box.
'94-'95.5 (cars with four wire coils) the wire is black/white and comes off both coils in parallel.
'95.5-'97 the black/white wire comes from the ECU.
'99-'05 it's a green/orange wire from the ECU.
#7
Boost Pope
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Yes. Those two signal are modulated onto the tach wire using a simple FSK algorithm. At the dash, a low-pass filter strips out the turn signal/fuel gauge signal for the tachometer feed, and a simple DC blocking cap is used to feed the FSK signal into a decoder which then derives the fuel and turn indicator data.
#10
Boost Pope
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Just so we're clear, every word of my last post was complete BS. The black/white tach wire has absolutely nothing at all to do with anything except the tach. Not the brake lights, not the OPG, not the blinker fluid level. Nothing.
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Zaphod
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10-26-2018 11:00 PM