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Ask Skyvisions Your Own Question
Skyvisions
Skyvisions, ASE Certified Technician
Category: Toyota
Satisfied Customers: 14354
Experience:  Toyota Master Diagnostic
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Had trouble sending message to you, did u get it?

Customer Question

Had trouble sending long message to you, did u get it ?
Submitted: 8 months ago.
Category: Toyota
Expert:  Skyvisions replied 8 months ago.

Did you replace either of the coils? Does the 1300 code still keep coming back? Do you have the DISTRIBUTOR at all or the 2 coil pack configuration?

Customer: replied 8 months ago.
Still not sure if you received my real question... but anyhow, the 96 toyota camary,2.2, le , has a single coil and distributor that are separated with a coil wire.. this was repaired before ,by changing ECM after doing the complete inspection procedure for dtc 1300 , from ALLDATA... In step 8, check for open and short between ign sw & ign coil, ign coil & igniter. I did come up with about 7. Ohms of a short, if that is considered a short. This ohm reading would go away when the EFI relay was removed. I was reluctant to change the ecm, but did , and the car ran well for a few months.now it dies at random,the dtc 1300 returned, also with dtc 0401.. I hope I'm not being confusing. I can answer with ease alot, I work on very large equip down to small. I earned several ASE certifications in 1984. I still don't know it all and respectfully ***** ***** help, thanks brian....
Expert:  Skyvisions replied 8 months ago.

A P 1300 code is extremely difficult to diagnose even for good technicians. You almost have to have an oscilloscope to check the trigger and feedback signals from pin number one and pin number two of the igniter to the engine control computer this code sets because the computer does not see an ignition confirmation from the. igniter. Is there any chance you have an oscilloscope or have access to one or someone that knows how to use one? Did you try another known good igniter? Are you 100% certain coil is strong and is snapping spark at least one quarter of an inch and is bright blue?

Customer: replied 8 months ago.
Step 5 would be use oscilloscope check waveform between terminal IGT and El of ECM. At that step a bad waveforms would mean change ecm, which did get changed, and the car started and ran well for months. However the dtc 1300 is back. Originally I did not use scope, but did change ecm. If a bad waveform was for now I would have to carefully question why it failed. Bad part ? That ohm reading I described earlier caused it ? I feel the slight conductivity in that test step 8 could a the problem, it is not a complete short ,but there is some continuity. Earlier I mention this ohm reading going away when the EFI relay is pulled out. I would assume that any reading would be considered a short.. I did give a fair effort to wiggle test to change that reading & also open some of the areas of the wiring for a visual inspection. Things like distributor, igniter,sensor at crankshaft, etc,etc,were also disconnected to change the reading. The EFI relay was what dropped the reading to OL ( no continuity ).. I maybe chasing the wrong problem ! Do know of the relation of the EFI and reading I'm getting in test 8 ?
Customer: replied 8 months ago.
The first time the problem occurred I had a good igniter to try, it didn't help, it got tried more than a few times. The seem good,it throws a blue arc over an inch.
Customer: replied 8 months ago.
The coil seemed good , !
Expert:  Skyvisions replied 8 months ago.

How the system works is the crankshaft position sensor and camshaft position sensor which are built into the distributor Send two waveforms to the engine control computer. It then calculates when it needs to send a trigger or IGT signal out to the igniter. The igniter then in turn grounds the negative side of the ignition coil for a predetermined amount of time then releases it which induces a secondary spark out of the ignition coil. When this happens the resulting feedback or magnetic field colapses around the coil sends a signal back to the igniter which in turn triggers a transistor that produces a square wave and sends it back to the engine control computer confirming that the secondary ignition took place for that cycle. The only way this code sets is if the feedback signal is not getting to the computer and a few rare cases I have seen where the trigger signal doesn't got sent out to the igniter due to possible wiring issues or pin fit issues and the computer doesn't see the obvious feedback signal because nothing triggered the igniter. With an oscilloscope you have a good ground then carefully back probe the IGT and IGF wires at the ignition coil to see if you're getting the patterns. Then check both wires at the computer and compare the signal wave forms. If there is high resistance either one of those wires or either one of those wires is even remotely shorted to ground it will kill the waveform. Because you monkeyed with the computer and replaced it it's possible you could have a loose pin fit at the connectors going to the computer. I would suspect that might be an issue. You need a pin fit gauge or an old computer that you can yank one of the pins out of and check your female pins in the connectors to make sure they're not loose. If you've already tried an igniter and you are 100% certain that you have a good ignition coil providing a good hot spark and field collapse then that only leaves a pin fit issue or wires between the igniter and the computer or the computer itself is failed again. I rarely see component failures a few igniters now and then but hardly ever a computer it usually wiring or pin fit issues. Click or copy the following link for additional information on how the system works.

http://facultyfiles.deanza.edu/gems/waltonjohn/Toyotaignition.pdf

Customer: replied 8 months ago.
I did question the pin tension last time, I have a Kent Moore connector set I measured the old ecm male pin with a dial caliper ,my set was not sized the same ,so didn't probe the harness for good fit,just looked at it. The ecm and connector was original & looked it was never touched before me, I genderly unplug, looked, repluged squarely. I don't need to make any assumptions, I will find the proper pin & check the connection. I will also seek out a scope. I followed that link, great information on therory of operation of different style of systems.I'm sure it's all in there somewhere , I have aptitude to only absorb a good portion of that, good stuff but only a few % of techs can translate that to the real world. When I get the car opened up again, & review it, I will go though the procedure , I'm looking at it rite now,listed in TROUBLE AREAS is - open or short in igf or igt circuit from igniter to ECM,,- igniter,, or ECM.. yes a scope would be handy. . If I need more help , hopefully I can reply again. Thank alot you have been helpful..
Expert:  Skyvisions replied 8 months ago.

You are welcome. Let me know how it goes.

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