How to make ST185 CS/RC WTA IC pump run constantly

[solrac]

Hi mates,

I decided to try to take this measure to call in some more horses

I've dug out the WTA IC ECU from the centre console, got a box
with P/N 89255-20030 slightly smaller than a pack of cigarettes
and having a 10pin connector.

I've pulled the cable from it and put ignition on.
This resulted in the pump running instantly and apparently
continuously and now I've got a check engine code 54.
I haven't tried to drive around because I suspect it may
have gotten into some sort of safe mode. I would like to
do things with a bit more knowledge than that. I've also
disassembled the box and found that there is a fairly
complicated circuit inside.

Has anyone figured out the pinout of this thing already?
Any other clues?

[Adydas]

i dont know on the CS but on the ST165 you can make a plug that will sort it out for you.

it just crosses 3 pins together using spades and some wire got from an auto sparky or such.

But someone would need to confirm both the ecus are the same.. Failing that you could wire it directly from the battery or other 12v source with a switch in the cabin / off the ign.

This would assumably throw up diagnostic errors on the main ecu tho ( or so do i belive ).

[solrac]

There are many forum topics I found on the net by g00gling about
the ST165 and the ST205. These are different both from each other
and the ST185 I believe. To me, ST205 seems to control the WTA
IC system by the main ECU instead of a separate ECU.

As I mentioned above, simple removal on the ST185 results in
a CEL code 54. What the ST165 guys are used to do is to fool the
main ECU into thinking that the WTA ECU is in place and all right.
I believe that this may not be the best approach because the
WTA ECU makes important checks like the level of the coolant
and whether the IC pump is running OK and it does that for a
reason. These are hard to spot failures which can also occur
while driving when they are even harder to realize.

When the coolant level drops too low or the pump stops, intake
air temperatures will skyrocket very soon and the engine will
start to knock apart. This is not what we want and thus I think
it would be best to keep the WTA ECU some way and hack it
just enough to run the pump constantly keeping it's diagnostic
functions.

For this I need the exact pinout of the WTA ECU plug and a
wiring diagram of the WTA IC system (how it communicates
with the main ECU, how it controls the pump through a relay(?) etc).
Doing research on the schematics / inner workings of the WTA ECU
would be a plus.

I'm of course working on the above and trying to get closer by
all possible means but sadly I'm not an electric engineer to just
look and recognise instantly what the circuits do nor do I want
to solder the PCB apart to test some of the parts out of circuit.
Currently I cannot figure out the pinouts of some transistors in
there. There is also a Nippon Denso special IC inside for which
I found absolutely no documentation about what it is, what it
does, etc.

Any knowledgeable hints or technical clues are very welcome!

[Malcolm]

there is a wire that runs from the W/A ecu to the engine ecu. I can't remember what colour it is, but if you have a multimeter you should be able to trace it. All you need to do is cut the wire where it goes in to the W/A ECU and earth it (so the engine ECU sees and earth signal). No more code 54.