Subaru 2002 WRX ECU weird issue

[eliotroyano]

Friends I need to check and test a Subaru 2002 WRX ECU that have a weird issue with main and sub engine fan driver controls. I need an schematic of that ECU, know which driver or transistor controls it or some advice what should check inside it? Pics are welcome too.

[eliotroyano]

Friends I need to check and test a Subaru 2002 WRX ECU that have a weird issue with main and sub engine fan driver controls. I need an schematic of that ECU, know which driver or transistor controls it or some advice what should check inside it? Pics are welcome too.

I Take some pics. I found the transistor. It is a CA19, but it is really weird that it got damage.

[eliotroyano]

I Take some pics. I found the transistor. It is a CA19, but it is really weird that it got damage.

Friends can you confirm me if that CA SMD transistor can be replaced by this one:
BCP68 Motorola (ON Semiconductors) P SOT223 20V 1A npn .
Anyone knows where can I find an schematic of this ecu board?

[eliotroyano]

Friends at least anyone can send me some tips?

[cjawahir]

Friends can you confirm me if that CA SMD transistor can be replaced by this one:
BCP68 Motorola (ON Semiconductors) P SOT223 20V 1A npn .
Anyone knows where can I find an schematic of this ecu board?

hi you can find this on old circuit board , if the speed is the same or more , it can work

speed = bandwidth

cj

[eliotroyano]

hi you can find this on old circuit board , if the speed is the same or more , it can work

speed = bandwidth

cj

I undersrand you friend but I do not have any old ECU. That is why I need to check the transistor to look a replacement.

I was searching more about the SMD transistor and found that it appears more to a BCX68 (SOT-89) than a BCP68(SOT223), basically is more like a SOT89 encapsulation than the other one.

About the specs, I was checking it out too, and due to the swicthing function that the transistor is doing some differences in the transistor speed should not affect a lot it operation, I think.

Checking how is connected the transistor in the board (base for ECU control, emitter connected to ground and collector for #86 pin of the FAN relay where #85 is +12V switched) and logging ECU procedure for FAN control it seems to operate more than a simple OFF-ON signal than a PWM control.

I also test the FAN control forcing ground to the relays (#86) and those starts normally, take out the ground and stay off like it usually does.

I hope all my thoughts be ok. I need to safe this ECU. I you know where to find more info about to repair or test these Denso ECUs will be a great help too.

[cjawahir]

I undersrand you friend but I do not have any old ECU. That is why I need to check the transistor to look a replacement.

I was searching more about the SMD transistor and found that it appears more to a BCX68 (SOT-89) than a BCP68(SOT223), basically is more like a SOT89 encapsulation than the other one.

About the specs, I was checking it out too, and due to the swicthing function that the transistor is doing some differences in the transistor speed should not affect a lot it operation, I think.

Checking how is connected the transistor in the board (base for ECU control, emitter connected to ground and collector for #86 pin of the FAN relay where #85 is +12V switched) and logging ECU procedure for FAN control it seems to operate more than a simple OFF-ON signal than a PWM control.

I also test the FAN control forcing ground to the relays (#86) and those starts normally, take out the ground and stay off like it usually does.

I hope all my thoughts be ok. I need to safe this ECU. I you know where to find more info about to repair or test these Denso ECUs will be a great help too.

i see you have all the right idea , its a simple switching circuit .

what you have to check is what cause the transistor to damage in the first place , mabe bad relay , bad wiring to relay .

check how much current the relay uses .

cj

[eliotroyano]

i see you have all the right idea , its a simple switching circuit .

what you have to check is what cause the transistor to damage in the first place , mabe bad relay , bad wiring to relay .

check how much current the relay uses .

cj

The problem starts testing the FAN system of other similar car. A friend change the relays with the car turned on and one of them makes the common spark sound when it was pushed in. . Also the car's temp was passed 100?C then ECU was requesting 1st and 2nd FAN speeds "on".

[cjawahir]

The problem starts testing the FAN system of other similar car. A friend change the relays with the car turned on and one of them makes the common spark sound when it was pushed in. . Also the car's temp was passed 100?C then ECU was requesting 1st and 2nd FAN speeds "on".

with basic eletronics when a transistor switch on a relay , you must put a diode accros the coil ,

because fthe high impedence of the coil when voltage is cut to the coil , the magnetic field cut and induce a high voltage back from where it came .

most car relay have a resistor built in , to reduce that shock , but you can put a diode also .

if you open a bmw relay you will see diode .

some times the jap cars the diode may be inside the ecu .

it not a problem to add a diode in the wiring .


cj

[eliotroyano]

with basic eletronics when a transistor switch on a relay , you must put a diode accros the coil ,
because fthe high impedence of the coil when voltage is cut to the coil , the magnetic field cut and induce a high voltage back from where it came .
most car relay have a resistor built in , to reduce that shock , but you can put a diode also .
if you open a bmw relay you will see diode .
some times the jap cars the diode may be inside the ecu .
it not a problem to add a diode in the wiring .
cj

Thanks for the comment friend. I know that. I check both OEM Subaru relays in this car and ECU as you see in the pics and it does not have the protection diode in it design. It is weird but I think that overvoltage due to coil operation when it was removed and conected again was the cause for transistor damage.

[cjawahir]

Thanks for the comment friend. I know that. I check both OEM Subaru relays in this car and ECU as you see in the pics and it does not have the protection diode in it design. It is weird but I think that overvoltage due to coil operation when it was removed and conected again was the cause for transistor damage.

i think the Engineer never expect some one to pull out the relay while the car is working , and said to them self if they did it will cost them a new ecu

how will they make money .


cj

[eliotroyano]

i think the Engineer never expect some one to pull out the relay while the car is working , and said to them self if they did it will cost them a new ecu
how will they make money .
cj

Yes I think so. Now I hope the BCX68 transistor can do the work as a right replacement for the CA-19 OEM transistors in the Subaru ECU board. I haven't found a precise info about this.