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Juan Crespo
Juan Crespo, Tech Trainer
Category: Toyota
Satisfied Customers: 1498
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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What is the signal level of the IGF coming out of the distributor

Customer Question

What is the signal level of the IGF coming out of the distributor ?
JA: The mechanics have tons of experience in that area. Are those all of the "symptoms"?
Customer: '93 corolla DX 1.8L A/T, cuts out at about 20 mph +/- depending on load, falls flat on it's face, will backfire if throttle is help down.
JA: Anything else I can tell the Toyota Mechanic before I connect you two?
Customer: Have replaced TPS, checked MAP for signal level, has a new distributor w/wires, I've read online that if the IGF signal is missing it shuts off the injectors (has code 14) I get an IGF signal but don't know if it's high enough for the computer to respond to ! As I read the signal it rises with RPM, is this the way it's supposed to act ? or is it supposed to be a 5V on/off signal ?
JA: Got it. Let's get this figured out. I'm sending you to a secure page on JustAnswer so you can place the $5 fully refundable deposit now. While you're filling out that form, I'll tell the Toyota Mechanic about your situation and connect you two. You'll be on the road in no time.
Submitted: 6 months ago.
Category: Toyota
Expert:  Juan Crespo replied 6 months ago.
Hi there.I'm going to guess that when you say "signal level" you actually mean signal amplitude or voltage. If so, see the circuit description below as well as the attached graphic.Circuit DescriptionThe ECM determines the ignition timing, turns on Tr1 at a predetermined angle (degree CA) before the desired ignition timing and outputs an ignition signal (IGT) "1" to the IIA (Distributor).Since the width of the IGT signal is constant, the dwell angle control circuit in the IIA determines the time the control circuit starts primary current flow to the ignition coil based on the engine speed and ignition timing one revolution ago, that is, the time the Tr2 turns on.When it reaches the ignition timing, the ECM turns Tr1 off and outputs the IGT signal "0". This turns Tr2 off, interrupting the primary current flow and generating a high voltage in the secondary coil which causes the spark plug to spark. Also, by the counter electromotive force generated when the primary current is interrupted, the IIA sends an ignition confirmation signal (IGF) to the ECM. The ECM stops fuel injection as a fail safe function when the IGF signal is not input to the ECM.Best regards.