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View Full Version : DIY 92-96 Prelude 4WS ECU Repair



ECU-MAN
02-09-2006, 11:24 PM
Disclaimer: The following is provided as a GUIDE ONLY, and neither myself nor Ozhonda take any responsibility for the outcomes of someone else doing the following. You follow these steps at your own risk!


this one is for the Prelude owners with 4WS problems. Although your 4WS may not be working, this DIY may or may not be the answer. There is a number of things that can go wrong with the 4WS system.

Best thing to do is start by checking the ECU for fault codes. If you get codes related to the rear motor, or the ECU it self then this DIY might be a good start.

problems this DIY might fix

- 4WS light comes on for no reason while driving after the 4WS was working ok
- 4WS light comes on for no reason while driving on a hot day after the 4WS was working ok
- 4WS light comes on for no reason while driving over bumps
- 4WS light on all the time

problems this DIY will not fix

- faulty steering angle sensors
- faulty rear actuator ( motor )
- miss-aligned sensors
- faulty WSS


if your not sure why your 4WS doesnt work you have nothing to loose by giving it a go, but thier may be other issues, well at least you have eliminated the common 4WS ECU problem.




Aim:

Fix 4WS, save some $$$$

Required:

- 10mm socket and a ratchet to drive it
- Philips head screw driver
- soldering iron
- solder
- electricity ( to power your soldering iron )
- anti static strap
- paper clip or a short connector
- long nose pliers


Steps 1

check the 4WS ECU for fault codes, need to locate the SCS connector and bridge it to put the 4WS ECU into diagnostic mode.

locate the blue SCS connector, drivers side floorwell, behind the center console

( see bellow pics )


http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair001.jpg


http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair002.jpg


unplug the blue connector in the red circle in above pic from the connector holder.


STEP 2

plug in the SCS connector ( or use a paper clip to bridge the connectors )


http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair003.jpg


and get your pen and paper ready

- turn on your Ignition to position II, the 4WS light will come on then go out and start to flash ( if the engine light, ABS and S4 light flash as well ignore them for now and read their codes later )

- count the flashes of the 4WS light, it will have two types of blinks. long ones and shot ones

http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair004.jpg

long ones = tens
short ones = units

example of light flashing

long long long long long long long short short = code 72


you must be patient, after about 2 min if flashing out the codes from the 1st CPU ( main codes ) the 4WS light will blink rapidly for 3 seconds and then the Sub codes will be flashed from the secondry CPU.

record your fault codes, cross refrence your codes from the chart in this great thread by bigteethygrin click here (http://www.ozhonda.com/forum/showthread.php?t=41105)

hopefully you will get codes in the 60's, these codes are common to this fault this DIY will fix.



STEP 3


reset the 4WS ECU and go for a drive to see if the ecu will register the same codes again.


http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair007.jpg




STEP 4

disconnect the car battery
this must be done

remove the 4WS ECU from the car

- remove the back LH seat


http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair009.jpg

- start by removing the lower cusion, the red arrows in the bellow picture shows where you have to lift the cusion and pull in the leaver ( while pushing down on the lower cusion )

http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair010.jpg

http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair011.jpg


- undo the 2 bolts in with your 10mm socket in red circles shown in the pic bellow and lift the seat back rest up and out

http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair012.jpg


STEP 5


the 4WS ECU is exposed

http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair014.jpg

- start by undoing the bolts in the red circles, move bracket out the way
- then undo the bolts in the blue circles

- only loosed the bolt in the green circle, move bracket out the way
- unclip the 3 connectors that plug into the ECU, see blue arrows above




STEP 6

in the bellow picture

- undo and remove the bolts in the red circles
- only loosen the bolts in the green circles

http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair015.jpg


http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair016.jpg



in the above picture

- pry open the black over by pushing the tabs back the green arrows are pointing to .
- undo the bolt the red arrow points to.




http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair018.jpg

- undo the 4 nuts in the green circles in above picture.

remove the 4WS ECU from the car


http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair019.jpg
its a big mumma




STEP 7


place the ECU on your workbench and put on your anti static wrist strap.

http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair020.jpg




- undo the screws in the green circles in above picture



STEP 8


http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair021.jpg



- undo all the screws in the green circles on the logic PCB on the right hand side, take extra care not to damage the flex on the top left corner that joints the two PCB's during this DIY.

- undo all the screws in the green circles on the left side of the ECU, then lift out the matal plate


STEP 9



http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair029.jpg


-undo the screws in the yellow circles, and lift the copper plates out of the way.

- undo the screws in the red circles and lift the relay out the way.

- now undo all the screws in the green circles,

this is what you will have


http://b16a2.kicks-ass.net/diy/4ws-ecu/95-BB6-4WS-ECU-repair031.jpg


- this is the PCB we will 1st inspect for dry solder joints..

- lift this PBC out of the chassis and place it on the bench and turn it over.



STEP 10


look at the PCB closely and inspect all the solder joints, use a magnifying glass if you have to.

you need to identify any solder joins that look ghetto like the ones in the picture bellow ( red circles )


http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair036.jpg



some may look ok but they may not be. this is the what a dry solder join looks like. here is a few more pics on different angles of the bad joints

http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair037.jpg



http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair040.jpg








STEP 11


- with your soldering iron reflow the solder on the bad solder joints. make sure the solder penetrates through the PCB but dont over do it and damamge the PCB. also to heat the crap out of it either.

http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair043.jpg


the above picturs are the common joints that suffer from dry solder joints . these are of the relay and relay connector joints, even if they look ok, reflow the solder joint.

I also like to reflow the solder joints of the drivers on the controller PCB



http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair048.jpg



as montioned before check over all the joints on both PCB's and use a magnifying glass if you have to. fix any you find to be sus.





Other comments

ECU-MAN
03-09-2006, 01:06 AM
STEP 12


Put the 4WS ECU back together again in revers from disassembly


http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair049.jpg



http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair050.jpg


http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair051.jpg




note; longer screw goes there.



STEP 13

http://ecu-man.com/diy/4ws-ecu/95-BB6-4WS-ECU-repair062.jpg

put the 4WS ECU back in the car.


- reconnect the battery


STEP 14

- start the engine and wait till the 4WS light goes out. then turn the wheel full lock to the left, then full lock to the right, then full lock to the left and full lock to the right then center.

this must be done as it sets the 4WS parameters in the 4WS ECU.


test drive the car and make sure everything is ok.

thats it

good luck.


Disclaimer: The following is provided as a GUIDE ONLY, and neither myself nor Ozhonda take any responsibility for the outcomes of someone else doing the following. You follow these steps at your own risk!

SiR JDM
03-09-2006, 02:40 PM
Quality work as per usual John. You are a machine, its that simple.

CUL8R
03-09-2006, 07:27 PM
john do u mind if i post this up on preludeaustralia? ofcourse giving u all the credit.
writeup would be a fantastic resource

preludacris
03-09-2006, 09:32 PM
yeah thats an awesome write up man !

not too many write ups like that for the lude..

no wonder this guy has so many dam rep points!!! haha crazzy

egSi
03-09-2006, 10:23 PM
wow.

john > everyone else on OH :eek: :thumbsup:

wynode
03-09-2006, 11:02 PM
+ PQ points for you again John :thumbsup:

Nice work and not a DIY you see often.

PS: It's spelt 'light' ;)

ECU-MAN
03-09-2006, 11:39 PM
john do u mind if i post this up on preludeaustralia? ofcourse giving u all the credit.
writeup would be a fantastic resource

yeah no probs, go for it.



PS: It's spelt 'light'

it was late when I finished this one :)

Ill give it the once over now :)

Eclipsor
03-09-2006, 11:47 PM
That's amazing work. Great diy.

Just a question. That's the second diy you've done involving fixing dry solder joints I think. The main relay one too.

Do you know why this seems to be a common problem? Did Honda or whoever manufactured these parts use an inferior mass soldering process?

Or is it simply the result of soldering parts on a car that's constantly vibrating?

ECU-MAN
04-09-2006, 12:08 AM
these items that need to have the solder reflowed cary a high current throu them constantly, then there is heat that is generated. its common for this to happen regardless of the quality of the sodlering process over a time period.

Its just nice to know you can fix them like this and not have to replace them.

Honda ECU are built and desined to a high quality and take alot of abuse where other manufature ECU would had failed ( think duracel bunny comercial ). I know alot of cars where the ECU is toast after a jump start gone wrong.


its just one of thoes things :)

CUL8R
07-09-2006, 09:43 AM
yeah no probs, go for it.
thank you john!
if u wanna check up on me ive posted it here (http://www.preludeaustralia.com/forum/showthread.php?p=234195#post234195)
thanx man im sure this will be appreciated by ALOT of 4th gen owners down in PA land :D

ECU-MAN
07-09-2006, 11:18 PM
no probs dude

thanks for the link

PaLo $oLdieR
25-04-2008, 10:29 PM
tahnx man!

roughly how long does the operation take?
my main relay took me a while 2 find the damn thing, other then that it was doone in 10 mins

ECU-MAN
26-04-2008, 03:14 PM
takes about 45min all up

dont rush it, take as long as you have to.

BigWillieStyles
12-08-2008, 11:56 PM
I actually did this a few years ago and fixed all the broken solderings and it worked. It never came back on again. But ive started having more issues with it again.

Ive heard people say to get a 4ws allignment, but i have never met anyone that says this worked, nor has it ever worked for me.

Is there anyone who has a shop that can fix these units?

ECU-MAN
13-08-2008, 09:12 AM
some times a wheel alignment makes it wors or causes problems that where not there if they dont lock the rear actuator when they alighn the car. the 4ws sensors all need to ber aligned coreclty along with a good wheel alignment.

JJprelude
22-12-2010, 11:00 AM
Looks like today is going to be a very long day. This should help a lot.