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[Steve W]

Omega MY98 onwards ABS/ TC lights on; speedometer not working

The first thing to try in this situation is to check and clean the ABS sensors on each wheel (especially the N/S/R which is where the speedo feed comes from)

If after doing this the lights are still on and the speedo isn't working then ideally find someone with a tech2 or similar system and see if the computer can communicate with the ABS ECU attached to the hydraulic modulator.

If it can't communicate with the ECU then the problem almost certainly lies with the ABS ECU itself. Unfortunately a very common problem, especially on MY98> versions (VIN W1000001 onwards)

Vauxhall charge about £800 to do the job all in with the unit itself costing about £300.

It is not a nice job to fit and requires patience amongst other things.

To access the unit you need to remove: (based on a 1998 3.0 MV6)

-Battery
-Engine relay/ ECU box
-Top radiator hose
-Coolant transfer pipe (thermostat feed pipe) (for clearance)
-Top plenum (optional but easier to locate the transfer pipe properly with it off)
-PAS pipe from top of pump for clearance
-PAS reservoir (ideally but can be moved out of the way, but will stretch pipes.)
-Undo all engine wiring loom round connectors from rear edge of battery tray.

When you are removing the PAS components note that the reservoir is directly above the ABS module, so make sure the fluid doesn't pour on the unit when you remove it.


The main top electrical plug on the ABS ECU has a sliding retaining clip. This slides towards the outside of the car, and is quite fiddly to get to even with all the bits out. You need to slide it as far as it will possibly go to allow the plug to come off.

Underneath the module is another, small, plug which has a more conventional plastic clip. Remove this and make sure the wire doesn't disappear into the bowels of the engine bay.

The ECU is held to the modulator with six small torx screws. The screws are well set back and in small apertures as can be seen from the picture below so you will need torx bits at least 2" long to actually reach the bolts. Also bear in mind with the unit on the car you can only actually see the top two screws. The rest are all done by touch, and a lot of luck.



To undo the bolts I used an angled screwdriver bit holder as there is extremely limited access to the bolts. See the following link:

http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=A331405&ts=46440&id=61688

Once all the screws are undone (You may lose a couple but the new unit should come with new screws) the unit should just come straight off. Be careful not to get any dirt or fluid on the exposed section of the ABS modulator, and give the surface where the module meets it a gentle clean.

Refitting is ther reversal of removal to quote Haynes, but fitting the screws is much more difficult than removing them. Gently fit the top two to hold the unit in place. What I did next was to use insulating tape to stick the screw heads to the torx bit then very gently try and locate them. This will take many tries and a lot of swearing. The advantage of insulating tape is that when the screws are tight the tape will slip off of the bolt.

Once all six bolts are in place reconnect the plugs, refit the coolant transfer hose (replace the two rubber O rings), refit the plenum if removed (replace the manifold to plenum seals).

From then on refit as normal, and when it is all back together with a little bit of luck the lights should go off and the speedo should work again.

This is not a job I would wish on to anyone, but my point here is that it is possible to do it as a DIY job, even if it is a pain in the arse, and you will save yourself £400 - 500 worth of labour.

Any questions feel free to mail me.

[Jimbob]

ABS ECU program info

The ABS ECU, needs to know a little about the car it is attached to, it needs to know Engine Size, and Gearbox type.

If you have bought a new ECU at about £300+ from Vauxhall, it will have no program configured on it

If you have sourced 2nd hand from Breakers, it could have any program on it.


If you have had your own ECU repaired, it SHOULD have its original program on it.

Sometimes you need to confirm / change it, and TECH2 is the way forward.


I have found some tech2 holders not to know much about this, probably due to it being not something they have done before.

They need to connect the Tech2 up, and go to the ABS module
They can then select programming
It is then a case of selecting the engine size( 2.5, 2.6, 3.0, 3.2) and transmission (auto / manual).

All will then be well.

So to confirm...

IF you buy a brand new ECU, it will have no program and need TECH2 to put on the program.

IF you buy 2nd hand, Same Gearbox and Engine, then no TECH2 should be needed.

IF you have your old ECU repaired by any of the repair companies, then TECH2 is normally not needed....HOWEVER we have now seen 1 ECU that has come back from repair with no config on it, somehow it has been wiped, in this instance TECH2 is needed to reprogram it.  This is normally evident from ABS working again, along with speedo etc, but the TC light remaining on, and you may also have an idleing / stalling problem.


Vaux/"My Naff Code Reader" claim to offer programming ability, I have not tested this, but IF your ECU has a program, then "My Naff Code Reader" claims to be able to change it, I havent tried this, or know anyone who has.  (The forum has seen instances when "My Naff Code Reader" has been used for programming, it has managed to corrupt the ECU, so use at your own risk)

If it has no config on, then "My Naff Code Reader" cannot add one, it will show you that the ECU is working and allow live data readings though.

In this case, you will get an error such as :

This control unit is only partially programmed!

Before you can use this control unit, a procedure
called SPS programming must be done.
This means, that a so called calibration file will be downloaded to the ECU.
This calibaration file contains important settings, and parameters.
"My Naff Code Reader" is currently unable to do this kind of programming.

For more information, please look at your user's guide.

[Kevin Wood]

A few pictures of this procedure which will hopefully be helpful:



Above we can see the ABS valve body from above (sadly I'd jumped the gun and removed the ECU before taking photos).

In the top left corner is the coolant transfer pipe where the top radiator hose has been removed. Note that I found the job was possible without removing the plenum and transfer pipe. The battery was removed, and the bracket holding the connectors behind the battery was unscrewed from the battery tray (1 screw) allowing these to be moved aside. The ECU/relay box remained in place and I loosened the bracket holding the PAS reservoir and moved this aside too.

On the centre of the left hand edge you can just see a U shaped section of power steering plumbing from the top of the pump. I had to loosen this and rotate it away from the ABS ECU to get a little more room to access the ECU mounting bolts. Make sure you remember to return this to its' original position or it could foul the aux. belt.

Slightly to the left of centre you can see the 2 pin connector which must be disconnected from the lower edge of the ECU.



Above is the ECU itself viewed from above and clearly showing the multi-way connector which connects to the vehicle loom. The bosses for the top two mounting bolts are also visible.



Above we look into the face of the ECU that normally contacts the valve body, showing the circular coils which each actuate one of the valves in the body. Be careful not to damage these during removal. All 6 mounting bolt locations are clearly visible here.



Above we can see the ECU from the side.



.. and from the bottom showing where the 2 pin connector locates.



This is the arrangement of tools which worked for me in removing the mounting bolts. Torx bit, extension, geared angle drive and stubby screwdriver head. Some blu-tack both on the torx head and inside the extension is useful to prevent either a bolt or the torx head from dropping out into the engine bay.



Looking back at the valve body from the battery location. The car will drive without an ECU present with relatively normal steering assistance and obviously no ABS, TC, cruise or speedometer. If it is used while the ECU is being refurbed, it's worth protecting the front face of the valve body with foam or similar, and make sure it is clean before refitting the ECU.

[Jimbob]

Thanks to GaryBC for an alternative ECU mounting arrangement as per
http://www.omegaowners.com/forum/YaBB.pl?num=1268659447



The first thing I would say is that by using longer screws and spacers made the job so much easier. See Figure 1. For the record I used 56mm screws and 35mm spacers for the middle pair, and 60mm screws and 37mm spacers for the bottom pair (and before anyone picks up on this no, you can't buy 56mm screws - you need a hacksaw!! Ditto the spacers).


Figure 1: Spacers

So. On with the job. Start siphoning coolant out of the header tank while removing the radiator shroud (two half-turn fasteners release the two little side sections, two hex-headed self tappers release the centre section). By now the header tank is empty so release the top end of the top hose and siphon as much as you can out of the block. While that is going on it is off with the battery. (Slacken the earth connector, walk round the car to the drivers door, reach in and turn the ignition on then off, walk back round to the front and lift the battery earth terminal - within 15 seconds. This prevents the power sounder going off apparently!!) Now disconnect the positive terminal, slide the battery jacket off, and remove the battery (a socket on a long extension bar will release the clamp). By now the coolant will be as low as it will go so release the lower end of the top hose (if, as I did, you replaced the spring clip with a decent Jubilee clip when you removed the ECU last week then this will take seconds, if not then you've got a fiddle on your hands!).


Figure 2: Small Lead

Time now to pull the harness out of the way. There's a (relatively) small cable running from the battery +ve terminal into the relay box on the n/s inner wing (indicated with the socket in Figure 2). Release it from the battery terminal clamp. Now; when you undid the +ve battery terminal, you had to unclip a fuseholder off the top of the battery, yes? Open it and you will see a 30A fuse on a green fuseholder. See Figure 3. Remove the fuse and slide the green holder out of it's mounting (it slides towards where the fuse was and is latched in place by a tiny barb at the back).


Figure 3: Green Fuseholder


Now the relay box. Open and remove the lid - it has lift-off hinges. See Figure 4. The wiring harness that comes into the relay box from the engine compartment only goes to three things: The ECU (simply slide it upwards on it's mounting plate - shown this way in the pic), two pink relays (release the catch - arrowed red in pic - attaching them to the wall of the relay box and the entire pink relay assembly slides up and away), and a single multi-pin connector - circled in yellow in the pic - (unplug it). Lift the entire harness up and out of the way. Nearly there!!



Figure 4: Relay Box


Behind the battery are three quick-release connectors. (I’m afraid I took no photos of this bit for some reason, but you can just see two of the connectors circled in pink in Figure 2 and Figure 3.) Turning the locking rings about 1/8 turn anti-clockwise will release them. Between the two largest ones is a screw holding the connector mounting plate to the battery mount. Remove it to free the connectors mount. You can now swing all the electrics out of the way.

It sounds a lot but it actually takes about as long to do it as I just took to type it all in!

Lastly, the power steering fluid reservoir. A single screw releases the clamp and one electrical connector frees it for removal.

Thus exposing, in all it's glory, the ABS unit all bagged up (you did bag it all up when you took it all apart last week, didn't you!!) and ready for the repaired ECU.

Nice long screws, a screwdriver bit taped to the screw head to give better purchase, all six screws in place in minutes! (Learning point here. I used slotted head screws (B&Q product code 5020789069758).You would be better to use Pozi/ Allen/ Torx headed screws as they would be easier to tighten then slotted heads. I found it quite a fiddle to keep a decent purchase when finally tightening up.)

Connect the two plugs and there you are - job jobbed!! Refitting, as they say, is the reverse of removal!

[tidla]

This one shows the pink relays, the black multiplug in the centre and the engine ecu moved out the way.
the single eyelet wire is from the "+" terminal.



If you don't fancy fighting with the three loom connectors on the battery tray edge, Just remove the single 8mm bolt and move away from the battery tray.

This is the under side of the loom connector bracket.