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1996 Toyota Tacoma 2.4L

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22 Aug 2017 22:39 #12233 by joshuamal
1996 Toyota Tacoma 2.4L was created by joshuamal
I was working on a 1996 Toyota truck in subject and I had no spark at the wires, so went to check spark coming out of coil and no spark, I checked fuses but all good, then noticed the fuel pump was not coming on, thought of checking EFI relay and swapped it with another one, was good, then I warned to check the ignition igniter but didn't know how to check it, i finally found out a ground wire from battery to chassis was missing or actually cut. That took care of the problem.
I want to be able to learn how to trouble shoot or test the igniter on this vehicle, I don't have scanners as all I have is test light and dvom. If someone can share a diagram of the ignition system showing igniter, coil, and explain me for future reference and learning experience

Thanks in advance

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24 Aug 2017 20:51 #12301 by Tyler
Replied by Tyler on topic 1996 Toyota Tacoma 2.4L
Here's what I've got for a diagram, courtesy of BBB Industries :



For my info, is this a coil-in-cap design? I'm not familiar with this system right off the top of my head, but I can take a shot at what's going on here. :cheer:

In this picture, the wire coming from the top left is a key on power feed, so pin 3 at the igniter should have 12V with the key on. Pin 5 is likely to be the coil control wire, which should pulse a test light connected to B+ engine cranking or running.

Pin 1 and 2 are part of the PCM's igniter control. I can't tell which is which from this diagram, but I know that one is called IGT (Ignition Trigger). It's the PCM's command to the igniter to fire the coil. The other is IGF (Ignition Feedback). This is the igniters signal to the PCM that it did indeed fire the coil as commanded. Unfortunately, it's tough to check these wires with a test light or DVOM, as the signal is very fast, and may not generate a reading on a multimeter.
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24 Aug 2017 21:14 #12305 by joshuamal
Replied by joshuamal on topic 1996 Toyota Tacoma 2.4L
Tyler, I appreciate your feedback on this. What would be a good way to test it or how would you test it or look for? I'm sure I will probably need to spend on a scan tool

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25 Aug 2017 09:29 #12311 by joshuamal
Replied by joshuamal on topic 1996 Toyota Tacoma 2.4L
Hello Tyler, this coil is inside the distributor cap not external. I'm trying to learn how to trouble shoot it as if I see another one I'll have the idea on how to do it. I went to my local CARQUEST store so they can let me use one just to try and see if it was the problem but wasn't, didn't have fuel pump action either, at the end it was the battery ground cable from terminal to frame. Let me know any feedback information you may have.

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26 Aug 2017 17:27 #12347 by Tyler
Replied by Tyler on topic 1996 Toyota Tacoma 2.4L
Wow, that Carquest let you use and return parts? Very nice of them. B)

Supposing you see no spark at the distributor, I'd suggest starting at black/white wire at the distributor. Connect a test light to B+ and check for pulsing during cranking. If you see pulsing, that shows that the igniter is working, and you likely have a coil issue. Check the power feed at pin 1 of the distributor before replacing.

If you do NOT see pulsing, there's an igniter issue. Next, recheck at pin 5 of the igniter. If you now see pulsing, there's an open in the black/white wire between the igniter and distributor. If you still see no pulsing, check power at pin 3 and ground at wherever the igniter mounts to.

If you have power and ground, then you're down to the IGT and IGF signals. The Snap-On Troubleshooter helped me out on this one. ;-) You CAN actually use your multimeter to diag these circuits. From Snap-On:

IGT Frequency Test

KOER, warm idle frequency should be about 25-30hz
Raise Engine RPM to 2500. Frequency should be about 120-130hz


This is the coil trigger signal from the PCM, which is key for the igniter to work. Obviously, the frequency of the signal will be much slower when cranking, but still useful! If your meter doesn't have a frequency option, you can also measure duty cycle:

IGT Duty Cycle Test

Duty cycle should be about 98%.


The IGF circuit can also be checked for frequency and duty cycle, though that one won't necessarily cause a no spark condition. The PCM actually uses the IGF for injector pulse timing, or so I'm told.

Do you still have access to the truck? If you really wanted to get familiar with these signals, you could try creating a no start condition by taking fuel away. Then, you could get some known good readings on these IGT/IGF circuits on a working system. ;-)

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26 Aug 2017 21:55 #12356 by joshuamal
Replied by joshuamal on topic 1996 Toyota Tacoma 2.4L
Tyler appreciate your help on this, I don't have the truck but I have a 1994 Toyota truck I can probably try that on it, soon I will be checking something else to the one truck and i suppose i can probably try it on it too. This will give me some knowledge on this appreciate your good help.

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27 Aug 2017 10:27 #12372 by Tyler
Replied by Tyler on topic 1996 Toyota Tacoma 2.4L
No problem! Let me know if those multimeter tests work or not, as I've never tested those circuits that way. :cheer:

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