Tony Reeves
Well-Known Member
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Hi Joe,Hi Tony, that answers a lot of questions, thanks for the info. However, it also brings up otherr questions...
If (on a standard ecu) you remove the appropriate 8 pin EEprom from the ecu then the immo is removed. However. If you leave the comms connection from CCU to ECU - OR - disconnect it, then the CCU disables the cranking via the starter relay. So in all cases afaik the ccu will disable crank without a valid comms link.
If I read you correctly, then you have the original CCU with a Jap ECU without IMMO. Yet on disconnecting the CCU - ECU comms the engine STILL starts ? - that I find confusing (based purely on the info I have). I considered a two way single wire data flow from the ccu to ecu with an ack return to the ccu to confirm key authenticity, however, this could not occur with ccu comms disconnected.
The question raised is - under what circumstances does the CCU enable start cranking unless a two way ACK / NAC is occurring.
You also appear to have this issue with the original ecu and ccu with comms disconnected. You also see a no crank ? - or, do you get crank but no start.?
This is highly confusing
The original CCU has to have a way to know when to enable the starter - NB - I have not tried this (yet) I have just ordered an ECU CCU matched combo to experiment with. I am purely going from researched info so far. It could be that the key fob data exchange with the CCU is enough to enable CCU Starter activation but the ECU needs comms for the Immo deactivation. If that is the case, removing comms would cause a crank but no start situation.
Can you confirm if this is the case or not ? - this bit confuses me Tony
"With the original ECU and CCU, if I disconnected the data line between the two, the engine would not start and run."
Joe
Yes, I see the confusion. My understanding - the CCU has two separate outputs as part of the immobiliser - the starter relay ground circuit and the line to send a code to the ECU. Both are effectively one way only.
When I started the conversion I was planning to at least temporarily just ground the starter relay, to make it work. I never needed to because the CCU was not immobilising so that line was always low (grounded) and the starter enabled, as long as +ve was available to the relay from the key start position.
I cannot see any two way transfer in this, the CCU outputs the 16 bit code and pulls the starter relay line low regardless of the state of the ECU.
Oh, BTW, when I said "the engine starts", I mean more than just the starter motor turns, rather the engine springs to life.
FWIW, circuit diagrams for my model.