Hi Volvo friends

I have a S70 automatic. The speedo sometimes cuts out and displays ZERO.
I have discovered that if I switch off the ignition and then switch it on immediately, the the speedo is activated again (seems to need a reboot!)
Does anyone have any ideas as the how to solve this please.

There are days when it behaves itself perfectly. Then I have a day where it will cut out a number on times in the day.
Thank you
Rodney
South Africa

Based on experience (friends and OWN) I would start at the ABS Modulator. It's a pricey piece of a small black box (at least in my country)...

:)

Have it tested first, before changing.

Hope it works out - update us please, especially if i am wrong on this one.

Could also be the electrical part of the ignition switch bad.
Do any lights come on or do you loose any other finctions?

Thanks for the suggestion. You can be sure it will be pricey here too.

By the way, you may well be onto something here. I discovered the hard way that my ABS is not working. On further investigation, the ABS warning light on the instrument cluster also does not come on when I switch on the ignition. I have had a techician plug in a fault finding unit and it reports that the ABS is faulty. He could not tell me more than that other than that the plug on the unit in the engine bay is connected.

I bought the car second hand from a Volvo dealer after a full safety check. Seems to me that someone has removed the globe from the instrument cluster or the globe is faulty. I plan to remove the dash board to check the globe. I believe this is a bit of a mision.

But first, where is the ABS modulator unit located? I will check the connections to make sure there are no obvious issues there before having the unit checked.

Thank you

Hi Tech

I have an idea that I lose the airconditioner at the same time. I will will observe what happens and let you know.

No other warning lights come on when the speedo switches off.

Next time this happens, rather than switch the ignition off and then on again, I will move the key in the ignition from side to side to see if anything happens.

Thanks for the suggestion

Rodney

I have found at least 2 sites on the net concerning the ABS removal. One of them is http://home.earthlink.net/~vicrocha/Volvo_...ABS_removal.htm

The ABS Modulator is in the hood. If you are facing the car with the hood popped, it's at the right-hand side. Behind the air filter.

Easier way to find look for the brake fluid fill.Then look all the way inder it.It is a black square box.it will have 2 plugs going to it.

Hi friends

Thanks for the guidance on where to find the ABS unit. I will explore and check the cables.

What I have established in the meantime is that when the speedo cuts out, no other warning lights appear on the instrument cluster.

The only other functionality I lose is related to the display of fuel consumption. When the speedo cuts out I also lose the distance travelled input and so the calculation of fuel consumption cannot be made either. Are these calculations done in the instrument cluster or elsewhere? This amy provide a clue.

I have taken the covering panel under the dash off so that the wiring is exposed above me feet. I have moved the key in it's socket and all the wiring I can reach while driving and nothing influences the speedo. It stays dead.

The only thing that will get it working again is to switch off the iginition and then switch on again immediately.

Would this give any indication as to where the source of the problem is? Could it be that I have an intermittent speedo connection problem at the sensor on the gearbox / drive shaft? I am wondering whether that input is suspended when on open circuit is detected and only reset again on switching the unit off and then on again.


Something else I have found is that my cruise control has stopped working completely - not only when the speedo cuts out. Could this be related?


The air con keeps on working by the way.

Many thanks

Rod,

One other related issue concerning the same problem, may well also be the ABS sensor. The sensor is located within the Brake Rotors / Discs 'hat'. Be careful when you take them out, as the plastic casing might break. They are at all four tyres.

And typically, a nice simple cleaning is all that is required for them to start functioning well.

I don't know if this is the case, but you may want to look at this first as it is a lot cheaper than an ABS Module. :grin: If the ABS Sensors are not at fault, hey, take pride cos at least, you've cleaned them out neeways. :)

Hope it helps, if not, just toss it aside. :grin:

Thanks tech and ampangbear for your suggestions.

I located the ABS unit (my car is a right hand drive) and I removed and refitted the 2 cables. Everything looks 100% there.

The link you gave me to a website with info on removing the unit was very helpful.

I have cleaned each of the ABS wheel sensors. The rear ones were especially dirty. This has made no difference to the speedo that cuts out nor to the ABS system which still does not work.

A comment I found on the website with info on how to remove the ABS controller caught my eye - and that was that the speedo will not work when the ABS controller has been removed. This would tend to support the idea that the problem is in fact the ABS controller.

Would it make sense for me to check the ABS warning globe first before removing the unit to have it checked.

The ABS warning light does not come on on start up - It is either faulty or has been removed.

How do I get to the globe please?

Many thanks

If that's the case, I too, believe that maybe your ABS is faulty. If the light does not come on on start up, then maybe the bulb is gone.

BTW, what do you mean by an ABS globe?

Thanks.
:)

I think he means how to get to the bulb to replace it.

You have to remove half of the top of the dash then remove the speedo cluster.

Yes indeed Tech is correct, by "globe" I mean the ABS light bulb in the instrument cluster.

Are there any tricks to removing the top half of the dash or is it fairly obvious?

I will do it this weekend.

Thank you

You will need to remoev the dash speaker,The plastic peice on the end of the dash then remove the screw behind the cover.You will also have to pop out the A/C vents to get to the other screws.

Once you lift the dash pad you will have to unlatch the latches holding the cluster to the dash.Then unplug the cluster.If your car is turbo and has a guage then don't forget to unplug the vaccum hose for the guage.

Becareful lifting up on the dash if the car has been in the sun alot it is possible for breakage to occure.It will break on some of the black plastic bye the windsheild.

Thanks, Tech. :wub:

Anyway, careful with the dash, you definitely don't want the dash to start making noises... :crying:


:)

All the best!

Hi Guys

Thanks for all the input.

After speaking to a Volvo mechanic, I finally gained access to the ABS light by removing the lower panel (above the pedals) and reaching upwards. The ABS light fitting had been removed (as I suspected). I swapped it with the service light and of course, the ABS light burns all the time.

I guess this more or less confirms that I have a problem with the control unit - just as you suspected in the very first posting ampangbear!

I have removed the unit and will try and have it tested during the week.

The cost of replacement is approx US$1100! I have mailed Vic (from the link you so kindly found for me ampangbear) to ask him a couple of questions.

Regards

Rodney

No problem, dude! I just had an experience on this myself, early this year. :)

Hope everything goes fine!