PeteGLi wrote:First off, apologies for the length of this post.
If none of the functions of the MFI work, including the clock:
The first step is to disconnect the earth at the battery and then re-connect it. This serves to clear and reset the computer memories.
Then check the fuse and whether other electrical items on the circuit work. If they are all ok, then there is either an interruption in the power supply or the earth to the MFI unit, or a break in the printed circuit or the unit is faulty.
To check for a power supply connect a voltmeter to the battery live connection to the dash, not forgetting to connect the negative lead of the voltmeter to a good earth.
You can check this without removing the instrument panel cluster.
The battery live connection is in the white plug at the rear on the rev counter side and to get at it you will first have to remove the under dash trim. It helps you to see what you are doing if you also remove the instrument panel surround, but do not at this stage remove the screw holding the instrument panel cluster at its centre top.
You may also like to remove the steering wheel. You will have to remove the steering wheel anyway, if you find you do have to remove the instrument panel cluster.
To remove the white plug, I found it easiest to reach up from under the dash with my left hand to the right of the steering column, grasp the plug (fingers to the outside of the car) and ease it off.
Bring the plug down under the dash without straining the wires. The wires you want are on the bottom of the plug as you now look at it, so turn the plug over so that the five wires in the centre five pins of the plug are facing you. The connection points at either end of the plug are not used. The battery live connection is the red wire second from the right as you now look at it.
Connect the positive probe of your voltmeter to this red wire and the negative probe to a good earth.
If there is no voltage present at this point, you will need to check back to the connection on the fusebox (Plug B, pin 12 on the back of the fusebox according to Haynes current flow diagram) to see if voltage is present there. If voltage is present at the fusebox but not at the dash, then check the wire between the two for breaks and continuity.
If voltage is present then you should check the earth continuity by connecting an ohmmeter to the earth connection at the dash plug – the brown wire second from the left on the white plug
and the battery earth. If the instrument panel cluster illumination lights work, then the earth connection is unlikely to be the problem, as they use the same earth.
If you have good voltage and a good earth then you need to check the printed circuit and it is at this point that you will have to remove the instrument panel cluster from the dashboard.
IGNORE the instructions in Haynes about how to remove the instrument panel cluster!! The connections on the back will prevent you getting the cluster anywhere near forward enough to be able to remove any of them if you try.
You have already removed the steering wheel, the under dash trim and one of the wiring connection plugs. You still have to remove the speedometer cable, the vacuum hose for the fuel consumption indicator and the other wiring connection plug on the other end of the instrument panel cluster.
To remove the speedometer cable, reach up from under the dash with your left hand to the left of the steering column till you can grasp the cable, squeeze the lugs gently and pull it off the back of the speedometer.
To remove the other wiring plug, I found it easiest to kneel outside the car and reach up under the dash with my right hand to the left of the steering column, grasp the plug and ease it off. Be careful here because there is a screw nearby that may catch your fingers if the plug comes off suddenly.
To remove the vacuum tubing, if you look under the dash you should see the hard opaque plastic tube coming through the bulkhead from the engine bay. This joins on to a flexible black rubber tube, which connects to the instrument panel cluster. Gently ease the plastic tube a few inches into the car, without putting a strain on the connection inside the engine bay. This will give you a bit more space to help in easing out the instrument panel cluster.
Now take out the retaining screw in the top centre of the instrument panel cluster and tip the cluster forward. You will find it catches at the top so press it down gently and ease it forward. You have to be careful that you do not catch the printed circuit from this point on.
The instrument panel cluster sits on two lugs sticking out at the bottom – one on each side. These locate in C shaped cutouts in metal supports built into the dash. You can just see the left hand side one in the next picture.
With the instrument panel cluster leaned forwards, lift it and, as the lugs disconnect from the supports, ease it slightly to the right, then still tilted ease the left hand side back into the dash and the right hand side carefully out the dash opening.
You cannot pull it all the way out yet because the vacuum tube is still attached, but because you eased the tube forward slightly, you should now have enough space to get a hand in and pull the tube off. It may be tight and need easing, but once off you should be able to lift the instrument panel cluster out, still tilted and taking care not to catch the printed circuit on any screws or protrusions.
Trace the live and the earth pathways through the printed circuit and check for continuity using an ohmmeter.
If the printed circuit is ok, then the MFI unit is faulty and should be replaced.
Refitting is the reverse of removal. Tilt the instrument panel cluster on its face, insert left hand end into the dash opening first. Re-attach the vacuum tube before you get the instrument panel cluster completely in. Once the right hand end is through the dash opening, ease the instrument panel cluster straight and locate the two lugs in the C shaped slots – I found this to be a little awkward as the left hand lug needed a bit of care in lining it up to sit properly. Tilt the instrument panel cluster back up carefully and re-fit the screw in the top centre. Reach in from underneath to re-fit both electrical plugs and the speedometer cable. Ease back the vacuum tube. Re-fit the instrument panel surround, steering wheel and under dash trim.
one that was requested that we shouldn't lose...
