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[Cybertrucker]

I'm now the proud owner of an N-registered CDX Diesel Turbo, after many years driving the Blue Oval. There are one or two minor problems with the motor, the most serious of which is that the speedo doesn't work so I'm reliant on my satnav to tell me how fast I'm going.

A friend of a friend, who's a mechanic for a local Vauxhall dealer, reckons it's the speedo head.  The head is apparently a weak point on the Omegas anyway, but the fact that the ABS light doesn't come on indicates that the ABS sensor in the NSF wheel, where the speedo gets its information from, is okay. (The odometer isn't registering either.)

A couple of things worry me though.  Firstly in searching this forum last night for posts about speedo faults I found one which suggested a link between speedo faults and power steering faults - my power steering is lighter at some times than at others. It may be completely unconnected, but is there something on the Omegas which varies the amount of power assistance you get depending on the car's speed, and which is getting confused by the lack of a speed input?  This might indicate that the problem isn't the speedo head after all, but a fault with the input into the head.

The second worrying thing is that the digital speed reading on the left-hand side of the instrument panel isn't working either, and neither is the mpg reading. (Nor is the cruise control.)  Do these get their speed information from the same place as the main speedo, which would indicate that it's the sensor which is faulty, or do they have their own speed sensors?  (Or do they get their information FROM the speedo head?)

Any advice on this would be very welcome - I currently have people scouring the country for a suitable speedo head, but if it's not the head I need to be looking for something else.

Thanks in advance.

[Varche]

Can't help with the speedo questions but some Omegas are equipped with speed sensitive PAS, I know mine is. Is it always lighter at the same speed?

varche

[Cybertrucker]

Can't help with the speedo questions but some Omegas are equipped with speed sensitive PAS, I know mine is. Is it always lighter at the same speed?

varche

Thanks for the reply.  No, it's not always lighter at the same speed, it seems to be random - sometimes it can be light when manoevring round a car park and other times a bit stiffer, and sometimes it's light at speed and at other times a bit heavier.

[TheBoy]

2.5TD has speed sensitive steering.

Speed signal for speedo, Fuel Computer, Engine (and thus cruise), and PAS all come from the ABS unit.

Saying that, pre 1998 ones are generally reliable - I've only seen 1 failure

[Cybertrucker]

2.5TD has speed sensitive steering.

Speed signal for speedo, Fuel Computer, Engine (and thus cruise), and PAS all come from the ABS unit.

Saying that, pre 1998 ones are generally reliable - I've only seen 1 failure

Thanks for that!  I was getting suspicious that everything which needs a speed input had failed - it suggested one central problem rather than two or more unrelated ones.

I think the ABS light is working properly (ie on for a few seconds then goes out), I'm pretty sure I checked it a couple of weeks ago, but I'll check again just in case the ABS is trying to report a fault and some bright spark has taken the bulb out.  I'll also try the ABS on the way home, by finding a quiet bit of road and stamping on the brake pedal.  (If the ABS doesn't work there may be one less Omega in the world by tea-time!)

Assuming the ABS light is okay, could there be some fault which will allow the ABS unit to function correctly but prevent the speed data being fed to the other things?  Even something as stupid as a multiplug having fallen out?

[Cybertrucker]

I think the ABS light is working properly (ie on for a few seconds then goes out) ...  I'll also try the ABS on the way home

UPDATE:

The ABS light comes on and goes out as per spec.  I tried the ABS on a quiet bit of road, but apart from giving myself a headache didn't really prove anything - the road was dry so was hard to skid on. I didn't feel any of the vibration which you get on a Granada when the ABS is kicking the brakes off and on, but the Omega ABS might be a bit more civilised than the Granada. The car stopped in an impressive manner though - if I hadn't been wearing the seat belt I think I'd have exited through the windscreen!

Further cause for worry - the digital speedo permanently reads 5mph at the moment, even when stationary.

Is this pointing to the ABS unit being faulty, or could there be something else?  If it is the ABS computer, how much can I expect to pay for a second-hand one, are they the same between different models, and how hard are they to swap?

[Entwood]

Have a read here ... might give you a few ideas ??

http://www.omegaowners.com/forum/YaBB.pl?num=1152729807

HTH