Hi everyone, I wanted to post this thread to share what I have learned troubleshooting an issue with my 1998 Z3 1.9L (built in 10/97) wipers as well as provide some extra documentation I know I wished there was online when I was researching the problem. Sorry in advance if this is lengthy, I just want to dump what I know in hopes it helps someone else out.
The Issue:
I first noticed this a few weeks ago when I used my washer jets, where the wiper blades would wipe for a few times, then stop randomly and could not be moved again without turning the car off an on. This caused me to test out the other functions, which I had seen work to an extent, but hadn’t used since the car was relatively new to me and I hadn’t driven it in the rain yet. The symptoms were as follows:
The wiring diagram for my Z3 was incredibly helpful, and I would like to give a huge thanks to @Pingu who had previously posted this link in a different thread, where I was able to get my diagram.
https://www.porterbility.co.uk/Z3_Wiring_Diagrams.htm
Wiper/Washer Module:
Having read some of the forums and looked at a video on YouTube of a teardown of a module from an e30, I had seen that the wiper module is fairly basic, but does contain an electrolytic capacitor. 30 year old capacitors tend to die, so I thought that was a good place to start troubleshooting. Having removed the glove box, I was able to get to the module and found that I had the Low system (see image below).
The wiper module is easy to open, just use a small flathead screwdriver to pry the plastic open and the whole board will slide out.
As you can see by the photo, these are fairly simple boards, only a single layer PCB and all through hole components. The electrolytic cap is a 47 uF 25V, and there is an IC from Elmos which I believe to be PN: 10001C, but I could not find any datasheets for it (if anyone has a datasheet for this part please pass it along). The relays used are Siemens v23076 a1001 c133. When searching for the datasheet for that part, I found one from TE connectivity which seems to be a compatible part.
https://www.bucek.name/pdf/v23076.pdf
Based on looking at the traces of the PCB and the wiring diagram, I figured out that the two relays are in series. The first one either acts as the input to the system, either connecting to GND or 12V. From there it connects to the common of the second relay, which selects between one of the two speeds at the coils of the motor. I put together a small diagram below to try and illustrate the point, although I do not know which speed is the fast or slow.
I had previously heard the relays ticking, so I was fairly confident that they were working.
Visually inspecting the board, there was no obvious corrosion or damage to the capacitor like I was expecting. At this point, I thought I should investigate the feedback in the wiper motor to see if that was the culprit, since it could make sense if the park feedback was broken and could no longer short that pin to ground when not in park, then the wipers would stop as soon as you let go of the lever on the single wipe, since to the module it would appear the wiper has returned to it’s park position.
With the wipers in park, I took my multimeter to the wiring harness for the module. If I was correct, in park I should see an open circuit between pins 1 and 7, and once I moved the wiper to the upwards position, I would see a short between them. I got the open circuit when the wipers were in the park position, but when I moved them I still got an open circuit.
The Wiper Motor:
I won’t go into the details of how to remove the wiper motor, since Pelican Parts already has a good guide on how to do so for a Z3.
https://www.pelicanparts.com/BMW/te...XgMEMwuFTiIu5_1dlqwTndYd_WtcychD3VNPFc2hmuCIQ
The only issue I found with their guide was the torx bit on my Z3 was a T30, not a T27, and I found it easier to remove the transmission linkage from the motor before attempting to remove it from the car, since it is a really tight fit and I didn’t want to risk breaking the plastic on the air intake which is located near the wiper motor.
With the motor out, there are 6 more torx screws to remove to get access to the inside of the motor. The back will lift off with a bit of resistance, which I used a flat head to pry open. Be careful doing so, as there is a paper gasket around the edge of the motor housing and you can tear it if not careful.
Inside, we find a worm gear that is driven by the motor, which causes the wiper arm to spin. On the plastic of the wiper arm output shaft there is a notch, which will depress the switch on the top cover. Based on the diagram, we would expect this is a normally closed switch for when the wiper is not in park, and when it goes in park the button is pressed and the switch closes, shorting the pin on the control to ground.
Hooking up my meter to pins 1 and 4 on the male header, I wanted to see if I could ever get the short to occur on the switch.
Lo and behold, I get an open circuit when the switch is both unpressed, and pressed, meaning after almost 30 years the switch has given up. It would also make sense that it failed in the open position, since this is the position for it being in park and that is where the wipers spend a majority of their time.
Conclusion:
This still begs the question why the wipers stop randomly when running if it is only a problem with feedback? My theory at the moment is the IC on the module must have some degree of smarts where if it does not see the wiper every leave park after so long, it will stop and go into a safe mode to prevent the motor from getting burned out if the motor was really stuck. Constantly changing wiper modes while driving must keep resetting this timer before the IC can reach the end, so it never goes into that safety mode.
So, with no other options, I have ordered a new motor which should be in later this week. I will update you all when I get it put in on how my wipers are working then.
The Issue:
I first noticed this a few weeks ago when I used my washer jets, where the wiper blades would wipe for a few times, then stop randomly and could not be moved again without turning the car off an on. This caused me to test out the other functions, which I had seen work to an extent, but hadn’t used since the car was relatively new to me and I hadn’t driven it in the rain yet. The symptoms were as follows:
- Washer nozzles (forwards on lever towards driver)– wipers go 10ish times, stop in random location and cannot be moved again until car is turned off.
- Single wipe (down on lever) – wipers will move only as long as the lever is held down, will stop as soon as let go.
- Intermittent, normal and fast settings (up progressively on the lever) – wipers will wipe 10ish times, then stop randomly and cannot be moved again until the car is turned off.
- Side note: it seems that as long as you keep changing between modes before the wipers stop, you can keep them going indefinitely. A bit annoying when driving to do, but useful if you absolutely have to drive in the rain.
The wiring diagram for my Z3 was incredibly helpful, and I would like to give a huge thanks to @Pingu who had previously posted this link in a different thread, where I was able to get my diagram.
https://www.porterbility.co.uk/Z3_Wiring_Diagrams.htm
Wiper/Washer Module:
Having read some of the forums and looked at a video on YouTube of a teardown of a module from an e30, I had seen that the wiper module is fairly basic, but does contain an electrolytic capacitor. 30 year old capacitors tend to die, so I thought that was a good place to start troubleshooting. Having removed the glove box, I was able to get to the module and found that I had the Low system (see image below).
The wiper module is easy to open, just use a small flathead screwdriver to pry the plastic open and the whole board will slide out.
As you can see by the photo, these are fairly simple boards, only a single layer PCB and all through hole components. The electrolytic cap is a 47 uF 25V, and there is an IC from Elmos which I believe to be PN: 10001C, but I could not find any datasheets for it (if anyone has a datasheet for this part please pass it along). The relays used are Siemens v23076 a1001 c133. When searching for the datasheet for that part, I found one from TE connectivity which seems to be a compatible part.
https://www.bucek.name/pdf/v23076.pdf
Based on looking at the traces of the PCB and the wiring diagram, I figured out that the two relays are in series. The first one either acts as the input to the system, either connecting to GND or 12V. From there it connects to the common of the second relay, which selects between one of the two speeds at the coils of the motor. I put together a small diagram below to try and illustrate the point, although I do not know which speed is the fast or slow.
I had previously heard the relays ticking, so I was fairly confident that they were working.
Visually inspecting the board, there was no obvious corrosion or damage to the capacitor like I was expecting. At this point, I thought I should investigate the feedback in the wiper motor to see if that was the culprit, since it could make sense if the park feedback was broken and could no longer short that pin to ground when not in park, then the wipers would stop as soon as you let go of the lever on the single wipe, since to the module it would appear the wiper has returned to it’s park position.
With the wipers in park, I took my multimeter to the wiring harness for the module. If I was correct, in park I should see an open circuit between pins 1 and 7, and once I moved the wiper to the upwards position, I would see a short between them. I got the open circuit when the wipers were in the park position, but when I moved them I still got an open circuit.
The Wiper Motor:
I won’t go into the details of how to remove the wiper motor, since Pelican Parts already has a good guide on how to do so for a Z3.
https://www.pelicanparts.com/BMW/te...XgMEMwuFTiIu5_1dlqwTndYd_WtcychD3VNPFc2hmuCIQ
The only issue I found with their guide was the torx bit on my Z3 was a T30, not a T27, and I found it easier to remove the transmission linkage from the motor before attempting to remove it from the car, since it is a really tight fit and I didn’t want to risk breaking the plastic on the air intake which is located near the wiper motor.
With the motor out, there are 6 more torx screws to remove to get access to the inside of the motor. The back will lift off with a bit of resistance, which I used a flat head to pry open. Be careful doing so, as there is a paper gasket around the edge of the motor housing and you can tear it if not careful.
Inside, we find a worm gear that is driven by the motor, which causes the wiper arm to spin. On the plastic of the wiper arm output shaft there is a notch, which will depress the switch on the top cover. Based on the diagram, we would expect this is a normally closed switch for when the wiper is not in park, and when it goes in park the button is pressed and the switch closes, shorting the pin on the control to ground.
Hooking up my meter to pins 1 and 4 on the male header, I wanted to see if I could ever get the short to occur on the switch.
Lo and behold, I get an open circuit when the switch is both unpressed, and pressed, meaning after almost 30 years the switch has given up. It would also make sense that it failed in the open position, since this is the position for it being in park and that is where the wipers spend a majority of their time.
Conclusion:
This still begs the question why the wipers stop randomly when running if it is only a problem with feedback? My theory at the moment is the IC on the module must have some degree of smarts where if it does not see the wiper every leave park after so long, it will stop and go into a safe mode to prevent the motor from getting burned out if the motor was really stuck. Constantly changing wiper modes while driving must keep resetting this timer before the IC can reach the end, so it never goes into that safety mode.
So, with no other options, I have ordered a new motor which should be in later this week. I will update you all when I get it put in on how my wipers are working then.
Last edited:
