Mikey-Mike Posted September 5 Share Posted September 5 My 2017 Fiesta has a problem where the screen washer pump works on the rear but not the front ! It makes no sense to me as I have already checked that the pump itself works in both directions by removing it and connecting a battery to it whilst holding it in a bowl of water, then reversing the wires, it shoots out water very well ! I have checked the wire that attaches to it from the car with my multimeter whilst getting someone to press the stalk and it shows 12v and then it shows - 12v if pulled back to do the rear. So the feed to it all seems good and the pump seems good, but I get nothing at all when on the car, it doesn't even try to work and makes no sound, but fine for the rear. I have checked all the 15amp fuses I can see on the fuse board but I would have thought if it was a fuse issue then it wouldn't work at all and there would not be the 12v reading on my meter ! The same if there was an issue with the stalk itself. I have tried testing it on the car with the water hoses disconnected in case they are blocked, but still nothing happening at all when I try to activate the front ! Incedently the windscreen wipers do come on when the stalk is pressed in. Anyone know what could be the problem here ! Quote Link to comment Share on other sites More sharing options...
unofix Posted September 5 Share Posted September 5 I suspect that the fault lies with the negative (ground) connection to the screen pump when you try to operate the front. The control of the screenwash pump is perhaps way more complicated than you would imagine. When the pump is required to operate for the front screen the ground connection is provided via the rear screenwash relay. If this relay has a high resistance on the normally closed contact or there is a poor ground connection then the pump will not operate for the front screen. See the schematics attached below (see the connection circled in yellow). 2017 Mk8 Fiesta 2 Quote Link to comment Share on other sites More sharing options...
Mikey-Mike Posted September 6 Author Share Posted September 6 Thanks for your reply on this Unofix. TBH your schematic diagrams don't mean a lot to me ! Where would I find the rear screen wash relay, I assume it would be in one of the fuse boxes, although mine look different to any diagrams of them I can find. Is there a way of testing this relay if I can find it, could I bypass it to determine if that is the faulty component ? Quote Link to comment Share on other sites More sharing options...
unofix Posted September 6 Share Posted September 6 The rear screen wash relay is part of the battery Junction Box (fusebox) it is a non-serviceable item. If the schematics are not helping you then it might be an idea to get an Auto electrician to take a look. Give hive the wiring information and he should be able to find the problem. Or of course have a drive up to sunny Durham and I'll take a look 🤣 1 Quote Link to comment Share on other sites More sharing options...
Mikey-Mike Posted September 16 Author Share Posted September 16 Hi again, I am still working on this problem but feel like I am almost there ! I have tried fitting a new pump bought from Fords, has made no difference, but at least I know it is definately not the pump. I have tried swopping the water hoses round and can get water spraying on the front windscreen by operating the stalk for ths rear window, so I know the hoses are fine. I have pushed a couple of wires up into the connector plug to the pump, pushed the stalk in and held it with tape. Put my multimeter on the other ends of the wires and it reads 12v. Bit when I hold these wires onto the male connector pins on the pump - nothing. But I then tried making another connection directly to the body of the car with another piece of wire to act as an earth. I then held the end of this to the pump along with the positive feed wire and the pump then whirred ! This would support unofixes reply about it not earthing properly through the rear screen wash relay. My problem now is trying to locate this relay, if this is the one causing the problem. I can't find any mention of it in anything I have or can see online. I have 2 fuse boxes, one under the bonnet and one behind the passinger glove box. Any help in identifying them from the pictures would be much appriciated ! Mike Quote Link to comment Share on other sites More sharing options...
unofix Posted September 16 Share Posted September 16 On 9/16/2023 at 5:51 PM, Mikey-Mike said: This would support unofixes reply about it not earthing properly through the rear screen wash relay 2017 Mk8 Fiesta The only thing that can cause the problem you have is if there is: No earth or a High resistance in the earth via the rear screen relay. You can not replace the relay as it is non-servicable and is part of the battery Junction Box. The fault is most probably a damaged or corroded wire from the rear screen wash relay (connector C1035B pin7) via splice "S104" to the earth point "G102" Disconnect the connector C1035B from the battery junction box (fusebox) and using a multimeter measure the resistance between pin 7 and the battery negative terminal. It should be less than 0.3 Ohms. I expect you will find it open circuit, or a very high resistance. 2 Quote Link to comment Share on other sites More sharing options...
iantt Posted September 16 Share Posted September 16 1 hour ago, unofix said: The only thing that can cause the problem you have is if there is: No earth or a High resistance in the earth via the rear screen relay. You can not replace the relay as it is non-servicable and is part of the Battery Junction Box. The fault is most probably a damaged or corroded wire from the rear screen wash relay (connector C1035B pin7) "S104" to the earth point "G102" Disconnect the connector C1035B from the battery junction box (fusebox) and using a multimeter measure the resistance between pin 7 and the battery negative terminal. It should be less than 0.3 Ohms. I expect you will find it open circuit, or a very high resistance. I think the fiesta is the mk7.5 by the looks of the fusebox photos posted up. 2017 could be mk7.5 or mk8 1 Quote Link to comment Share on other sites More sharing options...
unofix Posted September 16 Share Posted September 16 On 9/16/2023 at 9:23 PM, iantt said: I think the fiesta is the mk7.5 by the looks of the fusebox photos posted up. mmmmm........... Confused 🤔 Just reading back to the beginning the OP has said it's a 2017. I've been using the schematics for 2016 onwards. Looks like it is a Mk7 facelift and the schematics are those listed for the 2012 onwards !! Time to start again 🙁 1 Quote Link to comment Share on other sites More sharing options...
unofix Posted September 16 Share Posted September 16 @Mikey-Mike Can you please post a photo of the front of your car? Also what is the registration year ? for example: 65, 16, 66, 17, 67, Quote Link to comment Share on other sites More sharing options...
unofix Posted September 16 Share Posted September 16 2017 Mk7.5 Fiesta So...... Starting all over again, it seems your car is based on Ford model year 2012 and not 2017. There is good news and of course there is bad news. Firstly the control of the screen wash pump on your model is very simple. The two wires from the pump go directly to the Body Control Module (BCM) which is part of the passenger compartment fusebox (behind the glovebox). Connector "C2280A" pins 13 and 14. The BCM simply outputs the supply to the pump on these wires and depending on which screen needs washed it swaps the polarity of the supply to make the pump run clockwise or anti-clockwise. The command from the steering column screenwash switch sends either a positive or negative signal directly to the BCM on connector "C2280B" pins 13 and 14. Quite a simple system. Now the bad news. If the correct signal is being sent to the BCM from the screenwash switch and the pump will only run in one direction then the fault must be within the BCM with the control relay. Once again this is not a serviceable part and usually requires the BCM to be replaced. Some electronic repair companies may be able to desolder and replace the relay (if that is what it is) which could be a cheaper option. 1 Quote Link to comment Share on other sites More sharing options...
Mikey-Mike Posted September 17 Author Share Posted September 17 There she is, a 17 plate, 1.2 litre standard engine (not the eco boost) alloy wheels and low milage ! A very nice little car 🙂 I can't believe what I thought should be a fairly simple problem to fix has become so involved ! Thanks for the diagrams Unofix, but not being an auto electrician, I am again finding it hard to corrolate them with what I see in front of me when I look at the car. So from what you are saying the 'relay' is actually an integral part of the central fusebox and can't just be easily swopped out. I find this all very strange as all the other functions on the car work fine 🤔 I don't really want to start pulling the whole fusebox out so may have to take it to Fords to try and sort the problem. I have a feeling my local garage may become as confounded by it all as I have been ! 1 Quote Link to comment Share on other sites More sharing options...
unofix Posted September 17 Share Posted September 17 Thanks for the photo and confirming the 17 plate reg. The model is a Mk7 facelift (sometimes called Mk7.5). Introduced late 2012 and last built early 2017 before being replaced by the Mk8. The wiring on your car is based on Ford model year 2012 which is why we had so much confusion at the beginning. If you take it to a Ford dealer they will not attempt to repair the BCM and will just replace it. Expect a large bill of £600 plus labour. I've not personally taken the BCM apart for your model and so I can't say whether the screenwash is controlled by a built in physical relay or by a built in power transistor. What I can say is that it is not a user serviceable part. A cheaper option may be to get an auto electrician to take a look and confirm the fault. They would also be able to remove the BCM and possibly repair it, or will know a company who can. 2 Quote Link to comment Share on other sites More sharing options...
TomsFocus Posted September 18 Share Posted September 18 12 hours ago, Mikey-Mike said: There she is, a 17 plate, 1.2 litre standard engine (not the eco boost) alloy wheels and low milage! For future reference, it's actually a 1.25! That extra 50cc makes all the difference! But seriously, the Ka uses a 1.2 which is a totally different engine so best to distinguish between them. I would agree with Unofix that an auto electrician should be the next step for this fault, not a Ford dealership. 1 Quote Link to comment Share on other sites More sharing options...
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