Instrument panel on 1990 8v

[Engineer]

Hi,

last couple of moinths had problem with rev counter working intermitently.
Accompanied with water warning light blinking (just like when ignition first switched
 on) and MFA MPG function reads 1 mpg - though journey mile counter also wrong
so that may be reason MPG reading is very low. No car isn't doing 1mpg !!

MFA clock OK but sometimes pressing stalk doesn't cause display to move to next function.

I have found disconnecting then reconecting  battery lead has cleared a misreading MFA
in the  past but not now !


Anyone any thoughts as how to fix. Anyone  know how signal from speedo gets to MFA unit ?


Never had clocks out before  - any pit falls ?

Any help would be appreciated.

p.s. Moto meter instruments  but never any problem with them until now.

[...joe]

not 100% sure but i think with the motormeter clocks once they go, they go, so would need binning and replacing! not sure if you can use a set of vdo clocks instead as these seem to last alot longer. only thing to watch out for when removing the clocks is to not damage any of the tracks on the back. if you look at the thread about changing dash lights it'll give you a few tips.

[Engineer]

Thanks but I'm a bad loser !

I'll take the clocks out as it's kinda funny the digital clock works ( and  temp gauge but rev counter/trip and MPG doesn't.

There must be  a microprocessor in there somewhere and when they faiil then nothing usually works.
The fact  only the bit relating to mileage doesn't work makes me suspect the fault may not be microprocessor based but down to the bit that inputs mileage to the MFA unit.

just a guess but if anyone out there with experience of these things can help me the
I'd be delighted. 

[hockeylad72]

taking the ash cluster out the biggest pain is removing wiring block connector/s there is very little room to get you hands in to remove them.
I had similar problem with mpg, turned out if the speedo needle fluctuates causes a problem with mpg, had another problem with dash temp gauge and fuel gauge stopped working an easy fix replaced whole cluster with vdo one all sorted

this may be off some help to you
cheers

[Engineer]

Got clocks out no problem. Replacing with VDO is OK if you have the spare cash !

Anyone got a circuit diagram for the PCB on the clocks or can anyone tell me what sort of signals I should be seeing from the large black  connector to wiring harness. I presume the  ECU does all
calculations and the MFA electronics just puts the info on the display. I have an oscilloscope I have
used to fix all sorts of problems but it aint much use until I know what signals I should be seeing !

Years ago I used to see a regular advert for repair service to clocks - some where Staffordshire way
but no longer ! Anyone know of a repair service ?

[Judderi]

Before you go testing every circuit have you tried just plugging them in and out a few times to clean up the contacts. May sound daft but can often solve electrical issues.

[rubjonny]

Also check the earth from the rocker cover to the coil bracket is secure, and check the voltage stabiliser on the back of the clocks:

To test the voltage stabiliser, connect a voltmeter between the terminals shown (see illustration) with a 12 volt supply to the remaining terminal. A constant voltage of 10 volts must be registered. If the voltage is above 10.5 volts or below 9.5 volts renew the voltage stabiliser.