4WS ECU question

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Sat Dec 01, 2012 7:03 pm

The 4WS hasn't worked on the JDM for the whole time I've had it (just had its first aniversary, incidentally...).
The fault code said it was the ECU, I assume it's the usual solder problem but to save the aggro of opening it up and doing that, I bought a second hand replacement off PUK and it arrived this week.

Slaved it in earlier (fingers just about recovered the cold!) and 4WS now works aledgedly (light goes out after starting the engine).

BUT the part numbers on the ECUs are different;

Old one

39300-SS0-J61
Lot no. 2K30
E-4WS-SS
Big "ABS" on the right hand end of the sticker

Replacement

39300-SS0-J81
Lot no. 2T07
No additional line saying "E-4WS-SS" and no "ABS" extention on the sticker.

So has anybody got any idea what the difference is between the 2 ECU's please?

Thanks,

mercutio · Post by **mercutio** » Sat Dec 01, 2012 8:10 pm

maybe it has no output for the abs?

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Sat Dec 01, 2012 8:16 pm

Curious...
What output does it need for the ABS?
I thought the 4WS took an input from the ABS - so it knows what speed the car is doing, so it knows when to change from counter to co-steer? So I'd also assumed you didn't get 4WS on ludes without ABS?

YouTube · Post by **Sailor** » Sun Dec 02, 2012 1:40 am

wurlycorner wrote: Slaved it in earlier (fingers just about recovered the cold!) and 4WS now works aledgedly (light goes out after starting the engine).

But do the wheels turn?

Supermarine Blues · Post by **Supermarine Blues** » Sun Dec 02, 2012 2:32 pm

No, it uses the VSS to determine velocity, not ABS.

This guy has both versions:

http://allegro.pl/ShowItem2.php/itemNot ... ude-92-96r

and the correct one is cheaper.

Did some BB 1-4 come without ABS then?

Dbo · Post by **Dbo** » Sun Dec 02, 2012 2:56 pm

Yes my bb1 has no abs. It was a paid for upgrade at time of purchase.

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Sun Dec 02, 2012 3:54 pm

Sailor wrote: But do the wheels turn?

lol yep, that too (statically - still haven't been able to take it out for a spin)

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Sun Dec 02, 2012 4:12 pm

Supermarine Blues wrote:No, it uses the VSS to determine velocity, not ABS.

Interestingly though, when a rear ABS sensor goes down, it takes out the 4WS too (because the 4WS doesn't know how fast the car is going).

I wonder if that's the difference and it works like this;
Car without ABS, 4WS ECU takes VSS signal to determine vehicle speed
Car with ABS, 4WS ECU takes rear ABS sensor signal to determine vehicle speed
???

So if that's right, does that mean a car fitted with ABS doesn't take the VSS signal back to the 4WS ECU, so having fited a non-ABS 4WS ECU to my car, it'll always think the car is below 15mph so the wheels will always steer counter to the front?

I'll have to consult the manual in bit to see...

Edson · Post by **Edson** » Sun Dec 02, 2012 5:45 pm

Thought that the 4ws system is always connected with the ABS system.

It would be seriously impossible to get rid of the ABS and hold the 4ws system fully functional and vice versa.

Post by **Lude-dude** » Mon Dec 03, 2012 11:06 am

I think one ecu might just be a later revison

if it works dont complain