Disco 1 1995 Discovery 300TDi No washers working at all

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acprc

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Hi all,

Needing some assistance if possible? 1995 D1 300TDI and all the washer jets have packed in. Front, back and headlights. So far tried the following:

Drivers side fuses - checked
Washer relay (passenger footwell) - checked and replaced with new
Drivers stalk - replaced with good used
Slaved in new pump - nothing and no voltage at pump when switch thrown
Changed MFU (AMR 1280 Black version) for a used item - No difference
Checked earth in passenger footwell - (removed, cleaned and refitted)

I am presuming its electrical as front and rear screen are off different switches so sort of ruled out the individual switches. I am leaning towards the MFU but surprised if mine and the used one both didnt operate all the washers.

Any known weak points for the wiring on the washer circuit or anything else to try? Now getting to the point of pulling fuse box out again and trying to trace wires etc.

Thanks
 
Have you checked the water hoses themselves?

had this happen on the front of my 1996 D1 years ago and ended up replacing the hoses and it worked.
 
acprc said:
Hi all,

Needing some assistance if possible? 1995 D1 300TDI and all the washer jets have packed in. Front, back and headlights. So far tried the following:

Drivers side fuses - checked
Washer relay (passenger footwell) - checked and replaced with new
Drivers stalk - replaced with good used
Slaved in new pump - nothing and no voltage at pump when switch thrown
Changed MFU (AMR 1280 Black version) for a used item - No difference
Checked earth in passenger footwell - (removed, cleaned and refitted)

I am presuming its electrical as front and rear screen are off different switches so sort of ruled out the individual switches. I am leaning towards the MFU but surprised if mine and the used one both didnt operate all the washers.

Any known weak points for the wiring on the washer circuit or anything else to try? Now getting to the point of pulling fuse box out again and trying to trace wires etc.

Thanks
Click to expand...
So the wipers are ok then, so no issues with fuse 16 or 18.
Any hose or jet blockage the pump would still spin and it would be rare for all the pumps to stopped spinning together but I expect this not impossible.
The MFU (fuse 12) controls the wiper delays plus the wash/ wipe function and the sequence for the headlamp wash pump (fuse 2 lower aux panel).

So other than checking the 12v supply from fuse via switch, relay and at the pump the only common electrical point for the three pumps is the earth point, theres one in the passenger footwell… I believe, but if its not that one then theres another in the drivers footwell to look.
You have a wiring diagram don’t you ?
 
discool said:
So the wipers are ok then, so no issues with fuse 16 or 18.
Any hose or jet blockage the pump would still spin and it would be rare for all the pumps to stopped spinning together but I expect this not impossible.
The MFU (fuse 12) controls the wiper delays plus the wash/ wipe function and the sequence for the headlamp wash pump (fuse 2 lower aux panel).

So other than checking the 12v supply from fuse via switch, relay and at the pump the only common electrical point for the three pumps is the earth point, theres one in the passenger footwell… I believe, but if its not that one then theres another in the drivers footwell to look.
You have a wiring diagram don’t you ?
Click to expand...

Hi, thanks for the reply.

Yes both front and rear wipers work fine and fuses 16 and 18 are confirmed and tested ok. You are correct in that a hose blockage would still see the pumps work and I have slaved in a new pump at the washer reservoir with no action.

I have a copy of the LR 195 Electrical troubleshooting manual and its been invaluable for finding locations etc. Using that both the earth points in the footwells have been checked and cleaned. Nothing obvious with regards corrosion but it was done to be sure.
I am convinced this is something to do with the MFU or the signals from it and I think my next steps are tracing 12v from it, checking all connectors on the fusebox etc. The fact that all three pumps systems dont work, that they are controlled via differing switches (stalk and binnacle) leads me to the common items. Fuses and relays swapped for good and tested so all roads are leading to wires and or connectors.

Thanks for the help, appreciate it
 
MikeDISCO said:
Have you checked the water hoses themselves?

had this happen on the front of my 1996 D1 years ago and ended up replacing the hoses and it worked.
Click to expand...
Hoses all appear ok however pumps are not running when expected to be energized.
 
Check with multmeter if you have continuity to body or with a lamp against battery positive in any pump's plug black wire cos they share the same earth(as @discool already mentioned) cos as all are dead it's a good start
 
Last edited:
The MFU is involved with the wash pump relays by providing the earth to coil, is the MFU functioning? as already mentioned the supply is via fuse 2. A simple check is the interior lamps timing out, or wiper have a functioning delay still, rear fog lamps illuminating still the MFU looks after a few other things depends on vehicle spec.
My experience with the MFU is it fails completely, which mine it did 12 years ago, MFUs are not diy repairable so if found faulty… replace.
 
The MFU is not involved in the rear washer which is very simple as the pump gets direct power through the switch so if it was the MFU the rear washer should still work from the switch
 
Quick update,

The pumps have continuity to earth. Tested using multimeter on various points in the engine bay.
Fuses all checked again, fuse 2, 16 and 18 etc.
With headlights on, engine running and doors closed when you pull the column stalk I can hear the relay switching in the passenger footwell but no water
Rear wash switch does nothing, wiper works though
Interior lights do time out and rear fogs work

Original MFU was swapped out for a used one with no change previously. tempted to swap the original back in to see if anything changes.,
 
acprc said:
Rear wash switch does nothing,
Click to expand...
Check for voltage on the green/light green wire of the switch cos seems that there is a wiring issue which affects the power supply if the pump has earth... start with this rear one cos it's the simplest of all maybe it leads to the main issue too
 
Progress....ish!

There was voltage at the switch for the rear washer (Binnacle switch) but wouldnt make the rear wash operate. I have a bag of spare switches so put in a different switch and the rear washer sprung into life.
However, rear wiper now doesnt work however I am not confident the switch is ok as it sticks. Tried some electrical lube and no better so may need to get a replacement there. Checked all the fuses again in case something had blown but all ok.
1 out of three now appears to work.
 
How you'll have to see if power gets through the front washer relay's contact cos if it clicks means that the coil is working but the power doesnt get to the pumps through it. Maybe you are lucky and this relay is fubar on the contact side or it's a bad contact in it's socket
 
acprc said:
Progress....ish!

There was voltage at the switch for the rear washer (Binnacle switch) but wouldnt make the rear wash operate. I have a bag of spare switches so put in a different switch and the rear washer sprung into life.
However, rear wiper now doesnt work however I am not confident the switch is ok as it sticks. Tried some electrical lube and no better so may need to get a replacement there. Checked all the fuses again in case something had blown but all ok.
1 out of three now appears to work.
Click to expand...
The switch is ‘momentarily’ so just press and hold for the duration of wash and then release, the wiper operates automatically for 3 or 4 sweeps and stops.
The switch below just just press for the wiper, the MFU gives the wiper time delay around 6 seconds, so a single sweep every 6 seconds or there about.
 
discool said:
The MFU is involved with the 300 series D1 tailgate wash/wipe;)
Click to expand...
I'm sure that you'll realise soon(or already did) that it's not involved in the rear WASHER operation which was my statement, i didnt say anything about wipers ;)
from the 1995 D1 ETM:
upload_2023-4-9_16-46-21.png
 
sierrafery said:
How you'll have to see if power gets through the front washer relay's contact cos if it clicks means that the coil is working but the power doesnt get to the pumps through it. Maybe you are lucky and this relay is fubar on the contact side or it's a bad contact in it's socket
Click to expand...

Had a look at the relays and cleaned the contacts with electrical contact cleaner. Refitted relays and no change.

However, the rear wipe is now working as I closed the drivers door. Had no idea it made any difference to the rear wiper however at least I am 33% better off than the start of the day with the rear wash working!

I have given the old girl a wash now and will sit and take stock on what to do next but not quite given up yet. I think a start is new relays so I can exclude them.

I only have two relays mounted to the metal chassis, one with a blue base and one with a cream base, I think the rest are mainly ABS I I dont have that.

Appreciate the assistance.
 
Last edited:
sierrafery said:
You said you have the ETM, go to "connector" and see C2074 as it appears as the "power wash relay" in the diagram
Click to expand...

Hi, yes there are only two relays in that position and both have been on and off many times over the years i would bet. I think the only two I have are the Power wash relay K182 as connector C2074 and K176 the Dim/Dip relay C293. Both are not in the accurate position as per the ETM. Ordered two new relays, they are both the same part and will eliminate the relays with them...hopefully.

Personally I think its something else but starting to run out of ideas as to why no power appears to be getting past the relays to the pumps.
 
Last edited:
acprc said:
Hi, yes there are only two relays in that position and both have been on and off many times over the years i would bet. I think the only two I have are the Power wash relay K182 as connector C2074 and K176 the Dim/Dip relay C293. Both are not in the accurate position as per the ETM. Ordered two new relays, they are both the same part and will eliminate the relays with them...hopefully.

Personally I think its something else but starting to run out of ideas as to why no power appears to be getting past the relays to the pumps.
Click to expand...
Are you getting power to the socket that the relay plugs into? If so, you can jumper across to simulate the relay contacts and see what happens.
 
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