Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: terry paget on 04 May 2013, 16:19:03
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T367KHL 1999 2 litre petrol manual Omega - new thread
This car is due for MOT in MAY 2013. As advised in earlier threads, ABS light was on. I swopped ECU for an ECU I saved when from V687URP a 2 litre petrol manual Omega scrapped June 2012 which suffered a failed water pump bearing, causing cam belt to jump. The ABS on it was then working normally. Fault remained.
I checked all wheel sensors with resistance meter; all read 700 ohms.
All wheel reluctor rings looked OK. Rear sensors were aligned with reluctor wheels.
Tech2 said right front wheel sensor not seen.
I have checked pins 4 and 5 on socket at ECU end with meter - they show 700 ohms resistance. I then unplugged the connector at RH front wheel - pins 4 and 5 then showed open circuit.
I tried to replace front right sensor but allen screw is rusted in. Curses. To change front RH sensor I shall have to buy a scrap hub unit complete with sensor and fit that.
What course should I follow? Change RH front hub? Send ECU to ECUtesting for check and repair? Scrap car? Something else?
Please advise. Am running out of ideas.
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can you drill out the rusted bolt then retap the hole and fit your new snnsor ot soak it in plusgas and ues an easyout to get the bolt out just two sugestions
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if you want to swap out the front hub then i have one sat here in trowbridge you can try :y
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Hi Sassanach,
I should love to try your right hand front hub, presuming the ABS sensor bolt can be removed or the sensor is intact. Please let me know when I can pick it up! I am 15 miles away, e-mail terry.paget:btconnect com or 01761-412787
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Wouldn't post either your email addy or telephone number on an open forum mate - use the pm system ;)
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What's the pm system?
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What's the pm system?
Personal Message :y
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Thanks for the advice dbug. I have registered to send personal messages, but sassanach was not a registered recipient so I failed to contact him. Having announced my details anyway, I thank sassanach for his offer and appeal to him to make contact.
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You should be able to get the ABS sensor bolt out with an easy-out. if memory serves those bolts are only small torx bolts.
forgive me if I've misread and you've done it already.... but have you checked voltage going to the ABS sensor? :)
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Thanks for the thought, Webby the Bear. No, I have not get it out yet. What is an easy out? The screw appeared to be an internal allen headed screw. I hammered in an Allen key, turned until I rounded the allen hexagon. When last I had a similar problem the screw came out all tight but the sensor was stuck in. I suppose I might do better if I take the hub off and work with it on the bench. Then I could get hold of it with a Stilson wrench. I could also heat up the hub casting. That would probably release the thread, but cook the sensor, which is suspect anyway.
Sassanach has offered me a spare hub he has, but communication is proving difficult..
No I have not checked the voltage on the sensor. I presume there are 12 volts across it, provided down the cable from the ECU. Would it help if I checked the voltage? I presume one side is earthy and the other +12volts.
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here's a quick video of an easy-out being used...
http://www.youtube.com/watch?v=99eg03UN1VQ
you simply drill a hole in the stud that's stuck (you probably wont need to as you can use the already rounded off hole you've got). you then stick in your easy-out and turn it anti-clockwise. the way you turn it is as if youre undoing something.... but because its left handed thread it digs in the more you turn but has the affect of unscrewing the stuck fastener :y
dirt cheap off eBay. I think these were the ones I bought although I must admit I haven't had a chance to try these particular ones yet.
http://www.ebay.co.uk/itm/5-PIECE-PCE-DAMGED-SCREW-EXTRACTOR-CASE-BOLT-SCREW-STUD-REMOVER-EASY-OUT-/160832214896?pt=UK_Hand_Tools_Equipment&hash=item257258d770
As for the checking of the voltage... yeah I believe that's pretty much what youre wanting to do (i'm still learning myself :)). but if you disconnect the sensor. then hook your multimeter to a good ground and then your other lead to the terminals in the connector (coming from the ECU) then you should have battery voltage. if you don't then there could be a problem from that point backwards (i.e, a short circuit).
if I've got any of that wrong I hope someone will correct it for you shortly :)
HTH
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Thanks for the advice dbug. I have registered to send personal messages, but sassanach was not a registered recipient so I failed to contact him. Having announced my details anyway, I thank sassanach for his offer and appeal to him to make contact.
All members can send/receive pms - click on the right hand icon beneath sassanach's avatar when "send message" page will load. Fill i details and click "Send massage" button :y If it won't send recipients inbox possibly full ;)
HTH
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In addition to my note about the voltage... the thing you're testing would have to be turned on. so with the ABS I presume this system is always on when the car is running so would terry have to disconnect and then run the car to get a reading?
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In addition to my note about the voltage... the thing you're testing would have to be turned on. so with the ABS I presume this system is always on when the car is running so would terry have to disconnect and then run the car to get a reading?
Webby - I don't think the abs sensors are 'active' sensors so I don't think there will be a voltage to measure coming from the ECU.
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In addition to my note about the voltage... the thing you're testing would have to be turned on. so with the ABS I presume this system is always on when the car is running so would terry have to disconnect and then run the car to get a reading?
Webby - I don't think the abs sensors are 'active' sensors so I don't think there will be a voltage to measure coming from the ECU.
Ok fair enough. Thinking about I suppose they're only active when the wheels are moving. but anyway thanks for confirming :y
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You won't find a voltage at the ABS sensor. It generates an AC voltage when the car is in motion but it won't have a supply to it.
What the guy with the Tech 2 should have done is watch the wheel sensor output while the car was moving to check the reported speeds from all 4 wheels. That will tell you if you've got a totally dead sensor or just a reluctor ring that's missing pulses. Either way, it's not a difficult fault to solve with the correct diagnostics.
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Thanks Webby the Bear for that splendid demonstration of the easy out. I know them as screw extractors. I have used them in the past, the tricky thing can be drilling the hole in the screw centrally and as big as possible. I have two boxes of them on my garage shelf, missing the smallest extractors that I have broken off. I have found that if the head breaks off the screw or the hexagon rounds it is because the thread is rusted solid. then the only solution is heat.
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Thank you dbug. I did not know that. I cannot see how I should have divined it. Perhaps the envelope symbol and the talk of PMs should have told me.
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Thanks Kevin. The guy with the Tech2 was a generous sales director of a local Vx dealership. I go along occasionally when I am in trouble and he takes pity on me plugs in his Tech2 and tells me what it reads. In this case it said right hand front sensor not present. It's still puzzling, because it is still there, and is not open circuit, about 700 ohms, same as all the others. More puzzling is that when I plugged spare sensors into the RHF socket the ABS light remained on. But maybe the car has to move before it accepts a new sensor and turns its light off. I am under the impression that the front reluctor rings have no way of misbehaving, unlike the rear rings which have.
The front right sensor is now the chief suspect. Pity its stuck in.
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Thanks Kevin. The guy with the Tech2 was a generous sales director of a local Vx dealership. I go along occasionally when I am in trouble and he takes pity on me plugs in his Tech2 and tells me what it reads. In this case it said right hand front sensor not present. It's still puzzling, because it is still there, and is not open circuit, about 700 ohms, same as all the others. More puzzling is that when I plugged spare sensors into the RHF socket the ABS light remained on. But maybe the car has to move before it accepts a new sensor and turns its light off. I am under the impression that the front reluctor rings have no way of misbehaving, unlike the rear rings which have.
The front right sensor is now the chief suspect. Pity its stuck in.
I think that may be correct, as I had an ABS light on daughter's MG after having it on stands and turning rear wheels by hand, thus turning the diff, such that a discrepancy was monitored by the ABS, but it went off as soon as it was driven. :y
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Thanks Shackeng.
I now have the hub off the car. As advised last Friday by my best friend, Ray Hardcastle. aged 83 and now sadly dying of cancer, I put a hacksaw cut across a diameter of the screw, hammered the hub body where the screw enters, and applied a screwdriver to the screw head - and it turned!
However, with the screw removed, the sensor is still stuck in the hole. I have applied WD40 and am giwing it half an hour to seep through.
Comments invited.
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Plus gas is alot more effective :y
Allow to soak in, remove the wheel bearing assembly (if not already done), then apply heat to the hub and you should be able to drift the sensor out :y
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wd40 could'nt soak into a sponge ;D ;D
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besides you will almost certainly destroy it trying to remove it.(unless you get real lucky) :y
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Thank you for your support Gentlemen. You were right, of course. I have now removed the sensor, it came out in three pieces. I am now cleaning out the hole to accept my spare sensor, though I am not sure why. My spare is one I tried to get off an explod car with an ABS fault. It came out damaged. I have glued it back together again, but am not too confident in it. As I seem to be betting the farm on this sensor being the problem, it has to be a good one. On e-bay there are lots of rear sensors, but no front sensors. We all know why. The only front sensors come complete with front hubs.That is the way I shall have to go.
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I might have a spare front sensor if you end up needing one.Not sure,but if you get stuck give me a shout and I will have a search through my various boxes of bits. :y
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Be in the shed somewhere I shouldn't wonder ::)
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Thanks Albitz.
I have now cleaned up the hub and the sensor hole to receive my spare sensor. The old sensor consists of a coil of many turns of fine wire with a permanent magnet down its centre and a pole protruding at either end. The reluctor ring end pole is located very close to the steps in the reluctor ring, and is as wide as the gap in the teeth of the ring. I must work out how that creates an alternating current of frequency matching the wheel rpm.
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O level Physics :y the passing of the ridges cause a disruption of the magnetic field which in turn causes a current to form in the coil. The abs module then translates this as required :y
That's after 6 pints of cider though ::)
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Good thinking, ex taxi al.
This morning, bank holiday, at loose end, I decided to reassemble using my old repaired front sensor. On start up the ABS light came on, then went out. I backed car out of garage, parked, and went indoors to change to go for a long test. Turned car round, ABS light came on again. Bother.
Any opinions? What should I do next? I can now change the sensor easily, but can I get one cheaply? They are not listed in Trade Club book; I bet they are expensive. I can get a right front hub with sensor for £26 on e-bay and fit that. I could go back to Downside Motors and have a second Tech2 reading. Please advise.
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I still think you have the common fault where the aluminium wires break inside the ECU. I know you have tried another ECU that was working in a previous car but you didn't get that one on Tech II to see if it was showing the same fault as the ECU that is in the car now.
I worry that you have made unnecessary work for yourself by attacking the front wheel sensor.
I would still recommend getting your original ECU fixed by BBA reman.
For the best price on a genuine front wheel sensor I would contact andyc.
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Thanks Andy H. You could be right of course, though it seems unlikely that a spare ECU of good history should demonstrate a similar fault. I suppose I could swop ECUs between cars, but my only other 2 litre manual R706FHD is the spare car I gave to son Jonny while I prepare his for MOT. He lives 20 miles away. I forget how much ECUtesting charges for a 'test and find no fault' service. I suspect it was £100, same as for a repair.
I still have on the bench the ECU that I exchanged before. If I swopped that with the ECU in R706FHD that would settle it.
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Have just fitted a used front hub with ABS sensor. ABS light stays on, after 2 mile test drive. Is it ECU after all? Could it be nothing else?
Is there any point in putting back the other ECU?
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It needs proper diagnosis, IMHO. Could be ECU, wiring in vehicle or sensor.
Replacing the ECU with one from a scrap car isn't conclusive, IMHO. They all fail at around this age. Plenty of cars probably get scrapped at this point because they go to a main dealer and get a four figure quote to replace it with new. The chances of a second hand ECU also being faulty are not minimal, IMHO. :-\
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Thanks Kevin. I agree it needs competent diagnosis. I simply cannot think how to get one. I agree the fault must lie in the ECU, a sensor, or the vehicle wiring. The ECU I substituted was not bought from a scrap yard, I removed it myself from a car I scrapped last June after a failed water pump wrecked the engine; the ABS was working perfectly then so I assumed the ECU was OK.
I recall you suggested I should take the Tech2 man for a drive and let him compare sensor inputs. I doubt he would do that. I could put back the substitute ECU, then go back to him with different ECU and right front sensor and get a new Tech2 readout. Would that help?
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I think I would check that the resistance of the sensor can be seen between the ECU pins where it connects first. That way you can be confident that the wiring to the ECU is OK.
But.. when it comes to diagnosing further with the Tech 2, you only have to go round the block checking each wheel sensor input. In a straight line, they should all read the same speed.
The classic ECU failure results in a failure to even connect to the ECU for diagnosis, so it looks hopeful in that respect.
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Silly question, but are both front tyres the same size :-\
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Hi ex taxi al. Sensible question, but, sadly, all tyres are 205/65 R!5s. Worth checking.
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Hi Kevin, thank you for your thoughts. I did check pins 4 & 5 at ECU connector, as advised, and these indeed did show 700 ohms, and when I unplugged front right sensor to loom connector they went to open circuit. The Tech2 had said it could not see front right sensor. I saw no reason to doubt the other sensors were connected OK.
I cannot imagine why the wheel sensors should record different speeds if they are working at all. The tyres are an assortment, all nominally 205 65R15. I have run on assorted tyres for years in all my cars, including mixing sizes on occasions, without ever upsetting the ABS systems.
As suggested before, I wonder if it is worth while swopping the ECU again (the one now in the car is the original one) and asking the Tech2 what it sees then, with a different front right sensor and a different ECU, and having established connection between front right sensor and the connector socket, and having different aluminium wires from ECU connector plug to PCB.
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well either my multimeter is duff or 700 ohms is 800 ohms short off where they should be,the two i have here both read 1500 ohms and i know there okay.incidentally its no use sending pm's if you do read the replys or answer your phone!! ;D :y
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Hi Sassanach, thanks for you reply. Apologies for not collecting my message, I am new to the intricacies of the OOF, but am learning. Funny no-one answered the phone. Thanks for the message.
I am not sure of the actual value of the resistance of my sensors, they fall between ranges. Main point is they are all about the same, so it's a mystery that the Tech2 could not see the front right sensor, because it was the same resistance as the other three sensors, and it was connected through to the ECU socket. Where I go from here I do not know. Sleep on it perhaps.