Tricking the ECU to think there is an ICE

Technical discussion on converting internal combustion to electric
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Evit
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Tricking the ECU to think there is an ICE

Post by Evit » Fri, 18 May 2012, 17:28

What is the best way to trick the ECU in a vehicle which no longer has an ICE so that the airbags etc still work and the check engine light doesn't stay on?

Resistors and 5volt power supplies simulating the original sensor outputs?
Last edited by Evit on Fri, 18 May 2012, 07:29, edited 1 time in total.

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Johny
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Tricking the ECU to think there is an ICE

Post by Johny » Fri, 18 May 2012, 17:55

How did you determine that the airbag system gets data/input from the ECU?

Evit
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Tricking the ECU to think there is an ICE

Post by Evit » Fri, 18 May 2012, 18:26

I have not determined that it does, I just used that as an example. Some vehicles have the road speed sensor passing through the ECU before going to the dash so I am told.

I just thought that the ECU or some other computer may have a connection. Like when you turn the ignition on with a ICE all the lights are on the dash and once started they go out.

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Tricking the ECU to think there is an ICE

Post by zeva » Fri, 18 May 2012, 18:47

Pretty sure the airbags must operate 100% independent of the engine/ECU for safety reasons?

As for other things like the Check Engine light, in modern cars with CAN bus comms between ECU and dash, it can be a nightmare getting all the gauges to work and the Check Engine light suppressed - some black tape over the light is your easy solution!

Manufacturers use rather complicated proprietary comms on the CAN bus which (for a one-off conversion) is prohibitive to decode. The only feasible option may be leaving the ECU in place and simulate the engine's inputs to the ECU as you suggest. But even that may be too hard, as modern ECUs often do things like inductance tests on the fuel injectors and rate-of-change tests on tach and temp sensors, very hard to simulate satisfactorily..

Basically, speaking for myself I try to avoid converting any more CAN-based cars. (Plenty of beautiful old cars out there anyway!) For those already doing a new car.. perhaps just learn to ignore the Check Engine light? ;)
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Johny
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Tricking the ECU to think there is an ICE

Post by Johny » Fri, 18 May 2012, 18:47

In that case it's going to depend a lot on the actual vehicle. If it's recent it's probably CAN bus which becomes manufacturer specific. If you think they are analog or simple PWM signals then the best way is to measure and quantify them with an existing, running car that still has the ICE.
With airbags in particular, it's important to find out If there IS a connection from ECU into the airbag system. If so you will have to figure out it's protocol/format and emulate it. You will also have to prove what you have done to the Engineer so documentation is important regardless of what you find out.

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Tricking the ECU to think there is an ICE

Post by Evit » Fri, 18 May 2012, 19:43

Thanks Guys for the input.

I am trying to get my head around all the possible problems that may pop up in the conversion before embarking on the EV conversion.

I can quiet easily disable the check engine light, but it is the others like "Brake warning" etc which turn on with the ignition and off when the ICE starts and I will still need

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Tricking the ECU to think there is an ICE

Post by Johny » Fri, 18 May 2012, 19:48

Can you get your hands on a workshop manual? Sometimes (rarely) libraries have them. What make and model of car so we can help search?

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Richo
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Tricking the ECU to think there is an ICE

Post by Richo » Fri, 18 May 2012, 20:24

Assuming the airbag did go through the ECU the other issue is some don't activate below a certain speed. So the simulation to the ECU would have to be high enough to avoid this.

I would suggest get an after market steering wheel with no air bag and don't crash Image
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Tricking the ECU to think there is an ICE

Post by Evit » Fri, 18 May 2012, 20:48

Thanks again.

I have been offered a Nissan Navara with a dead 3l turbo diesel. Not the most ideal vehicle, but it is the right price, in great condition and will be useful. (as a ute)

The motor is a ZD30 with an electronic injector pump, not Common rail Diesel. It has an ECU which controls the injector timing and volume, so I am assuming that it will cause error and lights without all the sensors and injector pump connected. I have been told that the tacho and speedo information is fed to the dash and possibly the air bag from the ECU. I can live without a tacho or make some sort of circuit to emulate it.

How do most make the brake warning light work correctly?
Last edited by Evit on Fri, 18 May 2012, 10:50, edited 1 time in total.

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Tricking the ECU to think there is an ICE

Post by Johny » Fri, 18 May 2012, 21:38

This isn't everything you need by far but it may help.
See page 65. It looks like the speed sensor only feeds the speedo.
http://www.video2000.com.au/zd30/ZD30 Y61 Reference Document - BW.pdf

Evit
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Tricking the ECU to think there is an ICE

Post by Evit » Fri, 18 May 2012, 22:23

Thanks Johny. Image

It looks like the Tacho might be separate with a feed to the ECU (on page 65 also), I would just need to replicate the signal from the rev sensor for the tacho to work, the ECU to be happy and all the warning lights to stay off.

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Tricking the ECU to think there is an ICE

Post by ohmboy » Sat, 19 May 2012, 00:32

Ian (ibruinsma) here in Sydney has been attempting to outsmart his Smart car with the same idea. He is very close to completion. A lot harder than you may think on some cars.
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Evit
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Tricking the ECU to think there is an ICE

Post by Evit » Mon, 21 May 2012, 16:11

I expect it would be a matter of doing a diagnostic to see what is causing the error code, then replicating the signal and repeating until the ECU is happy.

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