ECU testing on bench..

[Jan1980]

Hi mates. I repaired some ecu?s and tested them on the car directly, work fine. But sometimes, car is far away and i get a damaged ecu shipped from a friend or a customer. Then, i have to test the ecu before reshipping.
I had MST9000, known ecu test unit from chinese sellers. I wasn?t happy with it, it didn?t work correctly for my case. So, my question, how do you test ecu on bench ?? Which tools do you recommend ?
I know, i can connect launch or DAS to read actual values and trouble codes. But i have to simulate a car on the bench. Can you help ?

THX !!!

[tranzavanza]

Hi there,

To test an ECU on a bench you need the following.

First you need to know that an ECU does not know if it is on a car or on a bench, So as long as all the requirements for the ecu to start working are met the ECU will Work.

An ECU is a device that responds to input signals , and it generates signals when the right input signals are there. I'll try to explain now:

ECU or ECM units need electrical force and flow to operate, The right voltage and amperage needs to be there for the ECU to Start, You need a way to control these two (volts- amps) A regulated power supply is a must, to work on devices on the bench, A healthy ECU will consume aprox 450 - 600 MA of current on a passive state (just the power supply on, No actuating or input signal processing)

-To power up the ECU on a bench you need to supply it with all the powers and grounds that it needs, I always use Mitchell and allData "combined" to come up with the right pinout. I recommend using a couple of switches to simulate the function of an ignition switch.


That's for the power, Now lets talk about signals.

The most important signal for the ECUs to start working is CKP and CMP, Some ECU will work with only one of them and some others will need both signals in order to operate. Out of the 2 signals the big player here will be ckp, so try to concentrate on that one mainly, The right ckp signal needs to be induced to the ECU otherwise it will not work. MST9000 does not have this capability for all the ECU, although is a great tool for verifying actuator functions (Coil, Injectors, fuel Pump, Relays).
To generate the signals you need a signal generator, You can make one using an arduino board and writing a simple program using commands high and low and controlling the on/off of the signal if it is a digital signal, You need to know the signature pattern of the signal you want to generate. You can obtain this from a good running vehicle using an oscilloscope and measuring Frequency, impedance, amplitude, duty cycle, and off-set if needed. If the type of signal is analog you can get away in most cases by using any type of signal generator found on ebay or the ones built-in on your MST9000.

One important thing to consider is IMMO. For most Vehicles this is stored only on the ECU, so asking your costumer for a key to test and having the right set up on your bench gig will do the trick, Turning off the IMMO while testing is another way to go around this However that topic is a big pain to deal with on its own. so you gotta figure out the best option according to the situation or device that you dealing with.

Other sensors like MAF, ECT, O2, MAP, TPS, ETC. Play also an important role in stabilizing The ECU operation. Trial and error will be the one here, There are no real courses or inexpensive classes that really talk about this topic, This is something that you have to learn on you own. Always use common sense, What ever the ECU needs on the vehicle to run, I'll need it on your bench

Most of the functions that can be tested of an ECU on the bench are Coil, Injector, Fuel Pump, and relay activation. Since most of this are activate by Ground pulses (For Most Vehicles) using your MST9000 is a great way to go with this. Otherwise you can build a tester with 1 LED and a resistor hooked up to power on one side of the circuit and leaving the ground side open to be closed by the computer actuator.

Please remember all this comes down to circuit design, you need to know how signals and actuators are produced and driven in that particular vehicle so you can create the right tester to test on the bench.

I hope this helps you a bit, if you have more questions let me know.

[Aajii]

I use programmable signal generator connected to pc. I have programmed common trigger patterns (it is possible to make "custom" trigger patterns).
I can recommend Rigol oscilloscope ds1204, 4ch . I have bought from batronix.
Some times it needs/good to have 4ch scope when measuring ecu timings...

[CustomCars]

That's good topic but fact is much different, many time cheaper (and that's will take much less time) is using second ecu to swap and test on car...
Much problem goes from MCU, so anyway in a lot case not easy to repair.

Signal generator and oscilloscope should be enough in most case. To check reading in ecu.