What current is expected at 12 to 14 volts in this minimum form ?
(looks like 1 amp on the PSW ?)
How much with basic sensors connected ?
Its about 100mA in this configuration, not much more with the basic sensors fitted, when you hook it up with an ignition switch and relays then it takes a couple of amps. On my test set I run reasonably high value power resistors for the injectors and EGR which is enough to keep the diagnostics happy with low enough power to run off a 5A supply.
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1984 Suzuki SJ413K pick up, 1.6 16V Baleno engine 2000 Suzuki Vitara 1.6 8V, many mods 2004 Suzuki Ignis 1.5VVT 4Grip 2006 Suzuki Jimny 1.3VVT JLX+ and many more.
I thought I would write an article demonstrating the minimum connections required to do some basic testing of an ECU. Two wires are required for power, 12V and Gnd and 12V needs to be applied to the main 12V supply pins to bypass the main relay. Bypassing the main relay has no effect on how the ECU starts up and runs so this is not an issue. A third wire is then required to connect a scan tool to the ECU, this is connected to the SDL pin.
For this example I have used a 1998 to 2000 Vitara ECU, the same ECU design is also used on Samurais of the same period. The schematic is reproduced below, the pins that are needed are shown highlighted. On this ECU the power and Gnd pins are paired in a manner that allows a standard spade connector to fit over two terminals at once.
For this type of wiring I generally use the small crimp terminals that are usually used for connecting speakers. If several wires need to be connected then I cut off the insulation and use heatshrink sleeving instead to make a more compact connector. The scan tool is connected to the ECU and to 12V and Gnd as shown below:
The scan tool is then connected to a laptop and the power turned on. The data that is displayed will vary between ECUs but on this 8V ECU battery voltage, default injector pulse width and ignition timing.
This is the most basic test that can be carried out but it proves that the ECU will power up and a large amount of the circuitry functions including the processor, the serial link, and the watchdog timer.
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1984 Suzuki SJ413K pick up, 1.6 16V Baleno engine 2000 Suzuki Vitara 1.6 8V, many mods 2004 Suzuki Ignis 1.5VVT 4Grip 2006 Suzuki Jimny 1.3VVT JLX+ and many more.
