ECC Power Stage Opinion

mrwassman · Post by **mrwassman** » 17 Jul 2011, 20:15

Hello all I am Spencer,

I just put a new Bosch fan motor in my 95 850 along with a new transistor in the power stage (T0-220 form factor) and also a cabin air filter. I "broke-in" the motor brushes with a battery I had laying around and after installing all of the parts I didn't get a single rotation.

Before I had a list of codes:

2-1-1
4-1-1
4-1-8
4-1-9

And afterwards the parts replacement I only got:

4-1-8

So I took the ECC apart to make sure it hadn't been smoked from previous owner and it looked spectacular.

Continuity between the units checked out and so did the voltage spec for the 418 code.

Do I have a 99% chance it is the power stage at this point?

Post by **Ozark Lee** » 17 Jul 2011, 21:42

Are you sure the gate, source, and drain have the same pinouts? I have seen a couple of writeups where they had to cross the leads on the replacement MOSFET to get things to work.

It may just be the picture but some other stuff on the power stage board looks kinda charred to me.

...Lee

mrwassman · Post by **mrwassman** » 17 Jul 2011, 23:14

The rest of the board looks great and doesn't have a bad smell.

I have tried two different transistors now and no response from the motor + Lights blink due to error (Previously reset).

The packaging is the mosfet that was in there and then I put in the alternative transistor that I also ordered(http://www.fairchildsemi.com/ds/FQ/FQP85N06.pdf) with some extended wires and still nothing.

mrwassman · Post by **mrwassman** » 17 Jul 2011, 23:15

Oh and the orientation is correct.

Post by **jimmy57** » 18 Jul 2011, 09:03

at this point it seems the next thing is to use wiring diagram and check to see if there is a signal change that corresponds to off position and then increasing fan speed. There should be two wires from ecu to power stage, one is the diagnostic/feedback and the other is the control. I believe the control is digital so watching for duty cycle change or voltage change as blower control knob is slid across range would work. The signal could also be a ground pulse output onto a reference voltage set by the power stage. The Vref missing from power stage may set the code in ECC so the source of problem could still be the power stage.

wyoben · Post by **wyoben** » 11 Mar 2024, 12:43

Put your dust mask on ,because I'm attemting to dust off this relic ...I'm Volvo for life so there are no options out I have a 1994 850 wagon W/ECC that I WONT sell ,therefore I MUST repair it ! That leads me to my current dillema the dreaded " Power Stage " back in 2011 ,when this thread was alive ,it was easy ...I would have just bought a new one ...that is NOT possible now ,they are like hens teeth...any way let me just cut to the kill since i may be barking at the moon anyway ! Does anyone know anyone that will attempt to repair my power stage , as I am near totally inept at soldering and mosfet type lingo ...i would gladly pay someone to do this for me ! I feel this is one task that should be delegated OUT ... also any further discussion and insoght on this matter is GRATEFULLY appreciated Thanks in advance ...cough ,cough, the dust is almost overwhelming in here !

jmartin919 · Post by **jmartin919** » 11 Mar 2024, 19:00

Have you tried this place? https://www.voluparts.com/

Post by **abscate** » 14 Mar 2024, 02:52

Cough cough cough…13 year old thread!

Does anyone know the part number for this stage so we can search for it, also year and chassis breaks?

Post by **scot850** » 14 Mar 2024, 10:38

By power stage, do you mean what we call (probably) wrongly the resistor pack? They do vary over the years in terms of part numbers as Volvo constantly changed the part numbers. I will be heading out to the garage later where my Vida computer is so I will look at part numbers if they are still listed. Problem is Volvo don't leave the part numbers anymore when they retire the part numbers.

Neil.

Post by **abscate** » 14 Mar 2024, 15:10

Correct. It’s not a resistor pack but often called that