Charlescrown wrote:Why not get a multimeter and do some simple testing. + - and 3X and 18X outputs on the 4 wires going to the plug.
Just did done tests earlier at the dfi plug.. see below (excuse the rough artwork, dine in the phone with greasy hands)
The sensors voltage ins seem weird/high but the outputs are at spec.. also getting that same voltage at the pcm when I backprobe.
I otherwise can't see anything wrong here.. have unplugged abs module, no difference except a new light in the dash.. still can't check codes, still no spark.
Has to be the pcm surely ??
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Last edited by UnknownSoldier on Sun Aug 21, 2022 6:11 pm, edited 1 time in total.
antus wrote:if the boot is triggered from the bcm and keyoff opens it then it sounds like the bcm might be faulty. if this is the case that could not transmit the bus heartbeat and cause a whole bunch of problems, even if the pcm is healthy. if thats it you'd need to replace the bcm and do a vats relearn, or disable vats in the pcm. if you have tuning tools you could turn vats off in the pcm, disconnect the bcm and then see if it starts at least. ive also heard the abs module tends to die and knock out the bus, so that might be another good module to disconnect first.
My apologies, this was actually a non issue but clumsy me pushing the boot release occasionally when I turned the key.. my new Chinese key shell has these weird over sensitive non clicking buttons with no feedback
The DIS module doesn't need the PCM at all to run the spark when it is in bypass mode (by default).
The PCM brings the DIS module out of bypass mode above 400 rpm and takes control once things are running.
charlay86 wrote:The DIS module doesn't need the PCM at all to run the spark when it is in bypass mode (by default).
The PCM brings the DIS module out of bypass mode above 400 rpm and takes control once things are running.
Oh wow.. thanks, that is great to know and makes it very interesting.. I did connect up another known working dfi but nothing changed.. the only thing I haven't replaced is the cam sensor but not sure if that's worth it, remembering I'm still seeing all the right voltages at the ecu and at the dfi .. .. I am even seeing voltage movements at the sensors/ecu when cranking which I believe is correct as it's 5v and 0v on and off to send the signal..
I'm pretty much out of ideas at this point, think it's time to suck it up and get an auto elec out.
charlay86 wrote:The DIS module doesn't need the PCM at all to run the spark when it is in bypass mode (by default).
The PCM brings the DIS module out of bypass mode above 400 rpm and takes control once things are running.
Oh wow.. thanks, that is great to know and makes it very interesting.. I did connect up another known working dfi but nothing changed.. the only thing I haven't replaced is the cam sensor but not sure if that's worth it, remembering I'm still seeing all the right voltages at the ecu and at the dfi .. .. I am even seeing voltage movements at the sensors/ecu when cranking which I believe is correct as it's 5v and 0v on and off to send the signal..
I'm pretty much out of ideas at this point, think it's time to suck it up and get an auto elec out.
Did you end up getting this sorted, have a customer car with the same/similar issue.
No 18x signal
6.6v going into the dfi pin
4.9 going out
4.9 going into the ecu pin
Have tried multiple cas sensors and dfi plates.
All wiring checks out
All pins check out
Cannot get it sorted for some reason
Had this about 4 years ago found my pcm plugs full of engine oil after basically replacing my CAS Cam sensor and DFI As i had a fault that kept recurring would start then die then just be dead for a few days then be fine for a week and die again.
When I gave up and tried another pcm thats when I found the oil build up it was a lot too I had to de pin flush out and reassemble since then car has been faultless. its strange how a failed oil sensor sent oil up the loom but it did.
Not saying that's what yours is but worth inspecting PCM for contamination.
