Wanna Give That Idiot Light A Use Again??
Hey guys, it was a nice day out today, so I decided to fuck around with my car. As I was cleaning and reorganizing my trunk, I got sidetracked and played around with the self test contraption I made. Anyway, I thought, why not see if I could give the old red replace engine light a new purpose... a real check engine light. So I figured out that the self test output wire in the self test plug (see link) http://fordfuelinjection.com/?p=13 was a computer controlled ground. When the key is on but engine is off, a ground path is made. This ground path with the existing wiring of the red light, makes the conversion possible (if you would call it a conversion?) The light in the dash gets 12 volts from ignition power. When ignition is in run, the computer's STO wire is grounded, allowing the light to be on. When the engine is running, and there are no codes, the ground path is not there any more and the light should be off. When there are codes, the light will be lit when the engine is running. This is where it gets even nicer. Now you can just take the STI (Self test input) or the one wire pigtail and put it to ground. And begin the self test. You can now monitor the codes through the check engine light in the dash.
Since I have gauges in place of the grounding sending units for the replace engine light, I just spliced into the one for the temperature sender, and ran a wire from there to the STO wire in the trapezoid looking connector. This is what they did with the '89+ or whenever they got the yellow engine light. Just ran a wire to the STO.
Since I have gauges in place of the grounding sending units for the replace engine light, I just spliced into the one for the temperature sender, and ran a wire from there to the STO wire in the trapezoid looking connector. This is what they did with the '89+ or whenever they got the yellow engine light. Just ran a wire to the STO.
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