Ignitor test?

WFO · 11-30-2009, 06:55 AM

I have a 99 4Runner 3.4 in my 91 4Runner. Swaped it in about a year ago. Everything has been working great up til the past week or so.

The tach would randomly not work when you start the truck. Come back a day later and it would work.

Now the truck wont start. Very weak to no spark

I have power at the ignitor and coil (both wires)

I have cleaned my grounds and added an extra ground from the engine to body.

Is there a way to test the ignitor? Napa want $430 for a new one and im not even sure its what I need.

Thanks in advance

If it makes any difference I am running a motor from an auto trans and an ECM from a manual. I re-pinned the connectors to match the different ECM. Again, everything has been working fine up until last week.

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BIG RON · 12-01-2009, 03:14 PM

make sure the bracket for the ignitor has a good ground.

UKrunner · 12-02-2009, 11:38 AM

Yes you can check. Find which pins go to the coils, find the one that goes to the rev counter, find the 12v. Find the one that sends the signal from the ecu to fire a coil. The remaining one should be the "fired" or "signal good" pin. It sends out a confirmation pulse to the ecu every time a spark signal is sent to a coil. If you have a scope you can look at the pulse train on that pin. If its not there or is skipping pulses, the ignitor or coils are bad. If all pulses are there and its not sparking or has a weak spark, coils, wires or plugs are bad.
You can also scope the individual wire to the coils. You could also have a bad connection from the ecu to the ignitor. Could be your ecu if the connection between it and the ignitor is good and pulses are missing from the ecu.

If you have the fsm a full test procedure is in there but you do need an oscilloscope to test it. Or you could connect a transistor to the wire under test and have it light an LED every time a pulse is present.

If you want to do it with an LED let me know and I will draw you a schematic.

WFO · 12-02-2009, 01:36 PM

Thanks i will have to check out the FSM again. I found the sheet that tells you how to check the coils and other sensors but all it said for the ignitor and ECM was try another one.

If you dont mind Id like to see how you test it with an LED

12-01-2009, 03:14 PM	#2 (permalink)
BIG RON Registered User Join Date: Nov 2005 Location: Rancho Cucamonga Posts: 240	make sure the bracket for the ignitor has a good ground. __________________ Concrete is the cancer of our land,just give me rocks and dirt..............

12-02-2009, 11:38 AM	#3 (permalink)
UKrunner Registered User Join Date: Apr 2008 Posts: 191	Yes you can check. Find which pins go to the coils, find the one that goes to the rev counter, find the 12v. Find the one that sends the signal from the ecu to fire a coil. The remaining one should be the "fired" or "signal good" pin. It sends out a confirmation pulse to the ecu every time a spark signal is sent to a coil. If you have a scope you can look at the pulse train on that pin. If its not there or is skipping pulses, the ignitor or coils are bad. If all pulses are there and its not sparking or has a weak spark, coils, wires or plugs are bad. You can also scope the individual wire to the coils. You could also have a bad connection from the ecu to the ignitor. Could be your ecu if the connection between it and the ignitor is good and pulses are missing from the ecu. If you have the fsm a full test procedure is in there but you do need an oscilloscope to test it. Or you could connect a transistor to the wire under test and have it light an LED every time a pulse is present. If you want to do it with an LED let me know and I will draw you a schematic. Last edited by UKrunner; 12-02-2009 at 11:40 AM.

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12-02-2009, 01:36 PM	#4 (permalink)
WFO Registered User Join Date: Feb 2007 Location: Fredericksburg, VA Posts: 503	Thanks i will have to check out the FSM again. I found the sheet that tells you how to check the coils and other sensors but all it said for the ignitor and ECM was try another one. If you dont mind Id like to see how you test it with an LED