Wiper's not working (scuttle flood)

Hi all,

First time poster. I'm trying to sort the dead wipers on my daughter's 2010 C3.

The scuttle drains were blocked leading to the wiper motor being submerged in water. I've replaced this, but no dice.

Other than the permanent 12v supply, there is no supply to the slow or fast speed connector pins (this is what I believe them to be, based on what I've read). Fuses seem OK. I've also tried a few BSI resets.

Please could someone tell me what this box is (attached)? The cable coming from it is taped to the main wiper loom but I'm not sure if it's spliced into it. This too, was submerged, but I haven't yet taken it off for further investigation. From what I've read, the wiper relay is soldered to the fusebox so I'm not sure what this box is.

Planning to get the car connected to a diagnostic tool soon, but does anyone have any ideas in the meantime?

Cheers

Hi

Sorry but there doesn't seem to be any late model owners here to help you.

I'm not familiar with the later model C3 but I'll muddle through if I can.

Do you have a car alarm? The mounting bracket is not the same but on the earlier models the alarm siren was mounted under the scuttle panel. I vote it's the alarm siren.

The power for the wipers comes from the BSM the fuse box in the engine bay. If the old motor was submerged because of the clogged drains it may have failed because it seized up. If the 'new' wiper motor is serviceable you could assume that the old motor has blown a fuse or damaged something. While the fuses may be fine I have seen the BSM's damaged internally by excessive current draw. The circuit boards, fuse holders and the relays are usual suspects.

How are you checking the fuses and power? A multimeter? My C3 is off the road at the moment and I cant test it, but I think the engine must be running for the wipers to work?

Again, not sure about the later model cars, but on the earlier cars there are two source of power and two grounds. The two 12V sources are from the BSM (high speed and low speed via a selector relay) and they come from the one fuse. One ground goes from the motor directly to the chassis. This should be green with a yellow stripe. Check for continuity to chassis from this pin with your multimeter. This is the 'park' ground, to park the wiper in the down position. When the wipers are running, the BSI, the glove box fuse box, supplies another ground, but only while the wipers are selected. When the wipers are turned OFF the BSI removes the ground but the second (permanent) ground keeps the motor going until the wipers park, then that ground is removed by a switch and cam in the wiper assembly.

I am not sure but I believe when the engine is running 12V is supplied to the low speed windings of the motor. But the motor will not run as there is no ground (no park ground and no ground from the BSI). Once the wipers are selected or the driver hits the 'single wipe' function, the BSI supplies a ground to the motor and the wipers run. Once the wipers come off the park position, the park ground takes over until the wipers come back to the park position when that ground is removed. If the BSI keeps supplying a ground, the wipers keep going. And so on.

If you are missing power (12V) the problem will be in the BSM. If you are missing ground, the problem will be in the BSI. If the wipers stop as soon as you turn the wipers off (they should park), it will be the chassis ground. You can also check the electrical connector at the BSM for corrosion.

I hope this helps you with you fault finding.

LaurB wrote: ↑Thu Mar 03, 2022 8:14 pm Other than the permanent 12v supply, there is no supply to the slow or fast speed connector pins (this is what I believe them to be, based on what I've read).

I must learn to read peoples' posts...thoroughly!!!

I would say the "permanent 12v supply" of which you speak is actually the low speed power. So it looks like its the ground from the BSI (the glove box fuse box) that's the problem.
Does the BSI 'click' when you select a wiper function? Do you get an earth at one of the wiper connector pins when you select a wiper function?
If you select 'high speed' on the wipers, does the power move from one contact to another contact?
In the wiper electrical connector you should be able to figure out the permanent ground, low speed and high speed contacts. The remaining wire will go back to the BSI in the glove box. If you do not get continuity to chassis ground when the wipers are selected, on the remaining contact, then the problem is in the BSI or the wiring from the wipers to the BSI!

Thanks so much for your very detailed replies, Ozvtr. Very much appreciated.

The alarm sounder theory seems good to me, so I'll leave that for another time.

I've just found that there appears to be no power at F12 in the engine bay fuse box (tested both sides of the fuse with a mutimeter with the engine running and the wipers turned on), so I'll work through your suggestions now. I can't hear a relay clicking when operating the switch.

Thanks again. Will report back soon.

OK, I have a little more information. Hopefully it will be of some use.

The connection from motor body to earth is good. The green/yellow cable seems to be permanently connected to earth. I've tested this from the connector, with the wiper motor disconnected.

The brown wire does appear to be a permanent 12V, provided that the ignition is on. The remaining two (fast and slow supplies) are in fact receiving 12V, but only for a few seconds after being switched on at the stalk. They then drop to 0V. The motor does not turn, however. Your description about the switched earth should explain this, but it looks like the earth is permanently connected, so I'm not sure. I'm now wondering if the replacement motor is bad (it was a used one). I'm going to try to rig a supply straight to it to try to prove it one way or another.

Thanks again.

Right, I've made some progress! It seemed that the connectors (either at the motor or at the other side of the scuttle) were not making a good contact, particularly on the earth pin. Gave them a good spray of contact cleaner and tightened up the female side.

Where is I am at now is that the wipers work perfectly, in all stalk positions, but for only 10 seconds. Then they just stop. I've found that this also affects the washer pump. If the wipers are running, the washer pump will work, if they aren't, it won't. Moving the stalk to any other position brings them back to life for another 10 seconds.

Is this confirmation of a BSI issue, perhaps?

Thanks again for all your help.

LaurB wrote: ↑Sat Mar 05, 2022 3:03 pm Is this confirmation of a BSI issue, perhaps?

Thanks again for all your help.

Hmm considering the system doesn't work the way I thought it did I'm not sure I'm being much help. You have done more to fix your problem than me!

You don't want it to be a BSI problem! That just a massive 8@ll ache!

If its an actual, predictable, 10 seconds, then that appears to be 'commanded' by something. Unfortunately that could be the COMS unit (switch stalks), BSI or BSM! They all communicate on the CAN BUS. Meaning that there are no switching wires to check.
Is it actually 10 seconds or random? The reason I ask is if its random, that might be a failing contact, like a switch in the COMs unit. If it's a predictable amount of time that indicates that it's being commanded off by something else. But what and why?

My "best guess" is the COMs unit BUT the problem is: the wiper motor and the COMs unit both failed at the same time!!?? What are the odds? Can your daughter confirm everything was working fine before? Is it possible the wipers were doing the 10 second thing and THEN it stopped working because of the flooding?

The wiper motor appears to be doing what it is supposed to do. I.E. run when there is power, stop when there is none.

The BSM 'logic' might be (I'm guessing)...no wipers, no washer. So the fact that the washer doesn't run when the wipers stop really doesn't mean anything. It's "normal".

I cant see anything in the BSM failing in this manor. Relays fail out right. Either the coil or the contacts. The semiconductor that drives the relay may over heat and fail, but not typically in a predictable manor.

As I said, the system (wipers) does not work the way I thought it does. The BSI does not appear to provide an earth for the wiper motor. In this case the BSI is just relaying instructions from the COMs unit to the BSM. There is no way it can interfere with the instructions from the COMs to the BSM over the CAN BUS. So it not likely to be the BSI.

I'm sorry, with out a circuit diagram I can only deduce things. I hope I am not leading you up the garden path.

I postulate that 'OFF' in the COMs unit is an actual position. Two contacts must 'make' in the OFF position. That is; it's not just the loss of continuity between two contacts that turns the wipers off. I theorize a contact is 'making' when you move the switch stalk but 'breaking' when the stalk is static. The COMs unit being an Electronic Control Unit runs the wipers in the last known position for 'a time' but in the absence of a command (no contact to any position) "fail safes" into OFF. Again, just a theory!!

Please ask your daughter if the wipers were working OK before they stopped altogether.

Thanks for your continued assistance and sorry for the slow reply!

If its an actual, predictable, 10 seconds, then that appears to be 'commanded' by something. Unfortunately that could be the COMS unit (switch stalks), BSI or BSM! They all communicate on the CAN BUS. Meaning that there are no switching wires to check.
Is it actually 10 seconds or random? The reason I ask is if its random, that might be a failing contact, like a switch in the COMs unit. If it's a predictable amount of time that indicates that it's being commanded off by something else. But what and why?

Yes, it's a predictable amount of time, exactly the same each time.

Can your daughter confirm everything was working fine before? Is it possible the wipers were doing the 10 second thing and THEN it stopped working because of the flooding?

There was a problem with the fast speed not working for the last couple of weeks before the total failure, but the 10 second thing has only just started to happen since the motor was replaced.

I postulate that 'OFF' in the COMs unit is an actual position. Two contacts must 'make' in the OFF position. That is; it's not just the loss of continuity between two contacts that turns the wipers off. I theorize a contact is 'making' when you move the switch stalk but 'breaking' when the stalk is static. The COMs unit being an Electronic Control Unit runs the wipers in the last known position for 'a time' but in the absence of a command (no contact to any position) "fail safes" into OFF. Again, just a theory!!

That does make sense. Something else I should mention is that when the 10 seconds is up, the wipers stop in their current position, rather than returning to the parked position. Similarly, if the wipers are turned off within the 10 second time window, they do not turn off immediately, but carry on until the 10 seconds is up, and stop mid-cycle.

I'm now wondering if the "permanent" live plays a part in all this. I'll check again, later today, and double check that it's reaching the motor.

Thanks again

LaurB wrote: ↑Mon Mar 07, 2022 11:07 am Something else I should mention is that when the 10 seconds is up, the wipers stop in their current position, rather than returning to the parked position. Similarly, if the wipers are turned off within the 10 second time window, they do not turn off immediately, but carry on until the 10 seconds is up, and stop mid-cycle.

Hmmm. If the green/yellow wire that goes to chassis ground from the motor connector is good, I would say there is some problem with the wiper/motor assembly. Could be a fault or could be the wrong assembly?

I'm still not sure how the electrical system of the wipers works, it's a bit confusing. If it runs for the 10 seconds and then parks, that's one fault. But if it runs for 10 seconds then stops dead...that seems like 2 faults!? No park function. But could it be 1 fault and how?

So the electrical connector has 4 wires? 1 permanent 12V. 1 permanent ground. 1 wire that goes to 12V for 10 seconds when low speed is selected. 1 wire that goes to 12V for 10 seconds when high speed is selected? But under no circumstances does the assembly park? It just stops at a random point on the windscreen? Hmmm.

So the electrical connector has 4 wires? 1 permanent 12V. 1 permanent ground. 1 wire that goes to 12V for 10 seconds when low speed is selected. 1 wire that goes to 12V for 10 seconds when high speed is selected? But under no circumstances does the assembly park? It just stops at a random point on the windscreen? Hmmm.

Exactly that, at least that's how it seems to me.

Could it be that the permanent live goes open-circuit at the motor once the wipers are in the parked position, such that when either of the fast/slow supplies are removed, the motor runs on due to its supply from the permanent live until a switch inside the motor disconnects it once parked? And could the BSI be sensing no current flow to this wire (assuming it's not reaching the motor) and cutting the other supplies after 10 seconds? That's my only theory.

Anyway, now that the car is "driveable" again, my daughter is using it so I might not be able to get my hands on it again until the weekend, so I'll report back once I've had another go!

Many thanks