problems with FAV solenoid - no work, but getting very hot! ::fixed::
 

After over 7 months of flawless function my HFS-3 kit seems to have problem now - there is no flow in the system ((((
Symptoms are following:

• There is no flow in the system under boost
• The FAV solenoid gets very hot instantly after system power-up (broken schematics??)
• The flow sensor shows full bar under boost although there is no flow at all
• The impedance if my solenoid compared to new one is the same - 12.5 Ohm (I did not try to install a new solenoid as I am afraid of braking it)

Definitely I will try installing backups FAV and its solenoid to test if there is issue in them, but if schematic of the main board is broken could it probably damage the new solenoid?
Also the FAV solenoid says about 6V DC operating voltage while HFS-3 documentation says about 12V/1A output - is it normal?

Should I anyhow check the actual output on FAV solenoid wiring?

Richard, I need your help, please....

Re: problems with FAV solenoid - no work, but getting very hot!
 

ok, some new info:

• the voltage on FAV solenoid is always around 13,6V
• I have tried installing a new FAV and solenoid assembly (from second kit) - no luck at all
• tested the pump - it works perfect (when disable jumper FAV and enable jumper SYS)

please, help!! how can I test that the mainboard is not broken?
today it worked for few minutes but later on stopped again ((((( should I check voltages on the mainboard diag pins?

Re: problems with FAV solenoid - no work, but getting very hot!
 

I have been thinking about your problem for a while.

I could not think of anything obvious. It appears the power transistor on the main board is blown. Before that, I would like to try a few questions with your help.

1. When you first switch on at pre-crank key position, does any one of the led on the controller lights up?

2. When you pull off the FAV jumper, does the FAV still gets hot?

Re: problems with FAV solenoid - no work, but getting very hot!
 

Richard,

I have did both checks and seems like your guess is right...

1. At pre-crank key position the water level light blinks for a second and then switches off.
Here you will see he result of check: http://www.youtube.com/watch?v=fFQw5h9UQGQ
2. As to the FAV jumper - regardless of its position there is constant 13.9V output on the wire.

Regards,
Alexey

Re: problems with FAV solenoid - no work, but getting very hot!
 

Okay, seems like this case is resolved - I took my HFS-3 to home and then in a bright light saw the blown up MOSFET transistor.
I still can't believe this has happened... why? shortcut on the FAV wire?

below is the picture of schematic with a clearly seen melted plastic.
how can I check that it is really dead one?

http://aklepikov.ru/wp-content/uploa...0611-00016.jpg

can it be replaced by any other high-voltage/frequency MOSFET transistor?
seems like it is quite hard to get exactly this one in Russia - what are the key parameters to look for (I would buy new one tomorrow)?

Re: problems with FAV solenoid - no work, but getting very hot!
 

The most obvious cause of a blown transistor is a short circuit. Other possibility is static electricity.

The transistor used is quite common, made by STMicroelectronics. STN3NF06L. It is good up to 4A. Logic level gate drive. You should not try to put a more powerful device in there. The next short-circuit means a burn out circuit board, not that easy to repair.

Here is the specification:

- Device name: STN3NF06L
- Vdss....... 60V (minimum)
- Id ............. 4A (minimum)
- Vgs(th) ............ 5V logic level
- Device outline package .............SOT-223
- Rds < 0.1 ohm.

You can search google for availability in Russia.

Re: problems with FAV solenoid - no work, but getting very hot!
 

Richard,

I have replaced transistor with a new one - but right after switching mainboard on it has burnt again.
What are other areas to check? Any voltage reference points to watch for?

Also recently my car was on a global maintenance and potentially someone in the service could brake something in the system setup?
I am really very much worried now as transistor replacement did not help (((

Regards,
Alexey

Re: problems with FAV solenoid - no work, but getting very hot!
 

Unplug the red harness and test it again. It will identify where the short circuit is. Cable or within the circuit board.

Richard

Re: problems with FAV solenoid - no work, but getting very hot!
 

Can you check the 12v supply to the unit is not wired to the ignition coil (+).

Re: problems with FAV solenoid - no work, but getting very hot!
 

what is the red harness?
how can I find what causing the short circuit if the transistor is already dead?