Lexus IS 200 2000 - Non start code P1305 ignition circuit current - Fixed #
Posted by Mark Robins on January 21, 2009, 7:06 pm
Year of Manufacture *: 2000 Engine Code or Type *: 1G ( Optional ) Scanner used: Autocom
Hi everyone,
Car came in as non-runner, engine momentarily starts then cuts out after about 2 secs. Serial codes are P1305 - Ignition circuit current. However by introducing carb cleaner into throttle body I can keep engine running for as long as I like (or until carb cleaner runs out!)Scoped the injector signal and that is disappearing after 2 secs but still have battery voltage at terminals. Do these have clear flood mode? I tried disconnecting the TPS but it made no difference, there are four wires on the TPS I take it one is reference volts earth and sig out, what's the fourth one for?. Are the injectors operated directly by the ECU or is there something I'm missing.
Any help greatly appreciated before I send the ECU for testing.
Mark
Re: Lexus IS 200 2000 - Non start code P1305 ignition circuit current #
The symptoms you describe usually mean the IGF signal is failing.This input is needed by the ECU to fire injectors.The fault is normally with the coil or amplifier,but the fault description of excess current would suggest a coil failure.The textbook method of verifing this is to view the current ramp of the coil using amp. probe and scope.Otherwise simply try a new coil.
Re: Lexus IS 200 2000 - Non start code P1305 ignition circuit current #
Thanks for the input David, this engine has six pencil coils are you saying one of them is faulty and causing the fault? I can scope the coil current ramps if possible but fail to see why it runs perfect on carb cleaner, or are you talking about single coil and distributor type set up? Sorry if I got the wires crossed!
Mark
Re: Lexus IS 200 2000 - Non start code P1305 ignition circuit current #
Sorry,Mark,I was referring to a distributor set up,but I think the same approach is needed with the COP system.If you can current ramp the coils it might tell you something.I take it that the P1305 code is a hard code and immediately returns after clearing.
Re: Lexus IS 200 2000 - Non start code P1305 ignition circuit current #
I checked current ramps on all coils and it turns out no 2 cyl has no ramp! changed coils over from 1 to 2 and 2 to 1 and fault remained on no 2 cyl. Checked what I believe Toyota calls IGT signal and it is missing. Question does this signal originate at the ECU? I have no tech data on this vehicle other than some info on a Yaris from James Dillon's Tech Topics where the ign set-up looks the same. Am I thinking right to check continuity of IGT wire back to ECU and if OK must have a ECU issue?
All help appreciated.
Mark
Re: Lexus IS 200 2000 - Non start code P1305 ignition circuit current #
It would appear to be either an ECU or wiring problem as IGT is generated by the ECU to trigger the coil.I've copied some info from Iatn which may be of interest,from this it seems your Lexus will run without IGF(but with MIL on) so it's a bit different to the older systems I'm used to.
Circuit Description The ignition timing (IGT) and ignition fail (IGF) signals provide crucial information in the control of ignition system timing, injection timing, and Fail-Safe activation. Based on an initial timing angle calculated from the NE and G signals, the ECM outputs an IGT signal to the igniter as a reference point from which it determines ignition dwell period. A special circuit inside the igniter controls the ignition dwell period by controlling when the power transistor is switched on. When the ECM determines the proper time to provide spark, it turns the IGT signal off, which turns the igniter power transistor off, producing a spark.
The IGF signal is used by the ECM to determine if the ignition system is working and to protect the catalytic converter. When the ECM does not detect the IGF signal, the ECM goes into fail-safe mode. With no IGF signal, the ECM will store a DTC(s), depending on model year and number of cylinders affected. There are different fail-safe modes depending on the ignition system, cylinder displacement and model year. The following is general summary.
IGT & IGF Signal Relationship
The IGT signal triggers the igniter power transistor. Without IGT, spark will not occur. The IGF signal confirms that an ignition event has occurred. Without IGF, the ECM shuts down injection pules.
General Summary If there is no IGF signal on engines before 1998 model year, the ECM will enter fail-safe and turn off all the fuel injectors.
Beginning with the 1998 model year, V-6 and V-8 engines equipped with direct ignition system with integrated ignition coil/igniter (1 ignition coil/lighter per cylinder), the engine will still run without the IGF signal, but the MIL will be on.
Beginning with the 2001 model year on 1 ignition coil/igniter per cylinder engines, the ECM fail-safe will turn off the fuel injector if there is no IGF signal for that cylinder and if engine conditions (such as load and temperature) are sufficient to damage the catalytic converter. If the IGF signal returns to normal while the engine is running, the injector may remain off until the next engine start.
Due to the rapid, high frequency nature of these signals, inspection should be performed using an oscilloscope or high quality digital multimeter with frequency capabilities.
Troubleshooting Hints
• On older systems, if engine will not start due to missing IGF, injectors will pulse once or twice during cranking. Use injector test light to confirm this condition.
• Scan data indicates an injection duration even when injectors are disabled due to IGF fuel cut fail-safe.
• Regardless of the type of IGF fail-safe mode, the IGF DTCs must be diagnosed before attempting to diagnose a fuel system/injection (P1305 is an IGF DTC) problem. The IGF DTCs are one trip DTCs.
• Use oscilloscope to diagnose IGT and IGF circuits.
Re: Lexus IS 200 2000 - Non start code P1305 ignition circuit current #
I sent the ECU of for test and repair and sure enough a fault was found on one of the coil drive outputs (Toyota IGT signal). The most likely cause of this fault I was informed is continual running with a misfire cased by a faulty coil. After "interrogating" the customer this was surely enough the cause. The interesting thing contrary to Toyota is that one ign coil drive signal loss caused all of the injectors to shut down, possibly due to the fact the car was driving until damage had been done to the ECU. My thanks to David Davies for his info and insight and to Avilec for their test and repair.
Mark Robins
Re: Fixed #
Posted by Glen Strachan on June 1, 2012, 8:11 am, in reply to "Fixed # "
Got one in today with exactly the same fault. It has had a history of missfires and the customer has been changing one coil pack at a time. Thanks for your hard work Mark :-)
on January 21, 2009, 10:06 pm, in reply to "