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location of ABS fuse M635

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85MSteinway
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location of ABS fuse M635

Post by 85MSteinway » Fri May 29, 2020 1:10 am

search isn't yielding results. My ABS light comes on at about 10-15mph. From what I've read that is most likely front brakes. I cleaned my speed sensors, they had a little bit of metallic dust on them. that didn't fix it. some of the helpful links posted on this site about diagnosing are no longer working. Does anyone have a link to diagnosing this? My next step I guess is to check the fuse, but I'm unsure of the location. Thanks a lot!

Jay
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85 M635

baders
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Re: location of ABS fuse M635

Post by baders » Fri May 29, 2020 2:33 am

Are your rear brake lights working ? If so, the fuse is good so most likely not a fuse. The ABS hydraulic unit and control unit are not fused. Is the ABS function working ? Wasn't there a whole thread on BC about ABS ?
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85MSteinway
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Re: location of ABS fuse M635

Post by 85MSteinway » Fri May 29, 2020 4:23 am

This is the most in depth thread I've found. http://bigcoupe.com/phpBB2/viewtopic.ph ... on#p119026

Reading the replies in that leads me to believe there is an ABS fuse. Perhaps inline in the harness? There is a link in that thread that leads to a ABS diagnostic but the link is broken as that particular thread is nearly 10 years old. If anyone has a working link to diagnose, that would be great! Or another more recent thread on bigcoupe. I thought I found something in another thread about putting a voltmeter to the sensors? But, now i cant find it again.

Jay
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Re: location of ABS fuse M635

Post by plip1953 » Fri May 29, 2020 8:30 am

I thought that if anything it was the rear reluctor rings that were prone to becoming clogged up?
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85MSteinway
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Re: location of ABS fuse M635

Post by 85MSteinway » Sat May 30, 2020 3:05 am

Can anyone advise on how to verify the sensors are what is triggering the fault? When I unplug them at the firewall and test Ohms I get about 1100-1200 on both. I don't want to spend the money on the sensors for an e28, splice them etc. just to find out that wasn't the issue. The sensors aren't cheap.

Jay
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85MSteinway
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Re: location of ABS fuse M635

Post by 85MSteinway » Sat May 30, 2020 3:33 am

Ok, just found a thread that said 800 Ohms is good and anything over 2k Ohms is faulty. I'm going to assume my fronts are good for now and move on to inspecting and testing the rears unless anyone has something to add.

Jay
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Re: location of ABS fuse M635

Post by 85MSteinway » Sat May 30, 2020 10:29 pm

cleaned rear sensor without removing as well as the toothed ring as best as possible from underneath. still no go. In this thread https://www.bimmerforums.com/forum/show ... at-caliper there is some ways to test, but I can't find my plugs for the rear sensors. it was said they are under the rear seats. I followed my wires as far as possible. from the rear wheel wells they enter the cabin under the rear seats. the right side comes over the the left side, under the carpet at on the far left side to the front of the car before vanishing somewhere near the firewall. Anyone know if 85 M635 even has disconnects for the rear sensors? and where they might be?

Jay
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ron
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Re: location of ABS fuse M635

Post by ron » Sun May 31, 2020 1:53 pm

Under rear seats. They go through rubber grommets (not shown in pics)
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85MSteinway
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Re: location of ABS fuse M635

Post by 85MSteinway » Sun May 31, 2020 5:56 pm

Ron, thats a great picture. thanks! I believe I found them. I was expecting them to be under the seats. they were tucked up a little further behind the square grommet accessible from behind the seats. Had to dig around a bit, but they are there with some extra slack. Thanks again.

Jay
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Re: location of ABS fuse M635

Post by 85MSteinway » Sun May 31, 2020 7:17 pm

That did it. finally diagnosed as left rear sensor. Thanks again for the pic, Ron. the connector on the left side wasn't actually embedded in the grommet and was tucked in between the cavity of the trunk and rear seat sheet metal. right side was in the grommet and that one was a pain to remove with all the fuel lines etc. blocking access. Now to find a new sensor.

Jay
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85 M635

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Re: location of ABS fuse M635

Post by plip1953 » Sun May 31, 2020 7:58 pm

85MSteinway wrote:
Sun May 31, 2020 7:17 pm
That did it. finally diagnosed as left rear sensor. Thanks again for the pic, Ron. the connector on the left side wasn't actually embedded in the grommet and was tucked in between the cavity of the trunk and rear seat sheet metal. right side was in the grommet and that one was a pain to remove with all the fuel lines etc. blocking access. Now to find a new sensor.

Jay
How did you confirm the sensor failure?
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85MSteinway
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Re: location of ABS fuse M635

Post by 85MSteinway » Mon Jun 01, 2020 10:03 pm

plip1953 wrote:
Sun May 31, 2020 7:58 pm
How did you confirm the sensor failure?
Disconnect all the sensors except one. drive the car above 15mph. if the ABS light comes on then its not that one. repeat process for all sensors till you find the sensor(s) that do not turn on the ABS light. I learned this from the bimmerforum link above, I would just amend the instructions to say that it is not necessary to remove the rear seats. you can get to the front plugs easy enough on either side of the firewall under the hood. The rear plugs are accessible from under the car. just pull the black grommet out and the connector is there. I did this while the car was on jacks, no need to remove wheels or anything.

Jay
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Re: location of ABS fuse M635

Post by plip1953 » Tue Jun 02, 2020 10:25 am

85MSteinway wrote:
Mon Jun 01, 2020 10:03 pm
plip1953 wrote:
Sun May 31, 2020 7:58 pm
How did you confirm the sensor failure?
Disconnect all the sensors except one. drive the car above 15mph. if the ABS light comes on then its not that one. repeat process for all sensors till you find the sensor(s) that do not turn on the ABS light. I learned this from the bimmerforum link above, I would just amend the instructions to say that it is not necessary to remove the rear seats. you can get to the front plugs easy enough on either side of the firewall under the hood. The rear plugs are accessible from under the car. just pull the black grommet out and the connector is there. I did this while the car was on jacks, no need to remove wheels or anything.

Jay
Sorry if I'm being stupid, but are you saying that with one good sensor connected the abs light will come on, but will not come on if a bad one is connected?

EDITED: I've now read the explanation of the test as you describe it (in that earlier link) and now understand the logic. So what I think this means is that you avoid a failure of something like our UK MOT by disconnecting all the sensors?
Phil
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85MSteinway
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Re: location of ABS fuse M635

Post by 85MSteinway » Tue Jun 02, 2020 5:23 pm

plip1953 wrote:
Tue Jun 02, 2020 10:25 am

EDITED: I've now read the explanation of the test as you describe it (in that earlier link) and now understand the logic. So what I think this means is that you avoid a failure of something like our UK MOT by disconnecting all the sensors?
if the sensor connected is the bad one it doesn't send a signal, and obviously the unconnected sensors wont be sending a signal so ABS thinks you aren't moving. if its a good sensor, it detects the signal, sees you are moving but none of the other 3 wheels register as moving and it errors. thats how I understand it anyway.


Now. anyone got a source for a rear wheel sensor? I'm having no luck. dealerships, Standard, Bosch, and Triscan are coming up with nothing. I've also tried finding it at local junk yards, with no luck there as well. Has anyone been able to use one from another vehicle with Bosch sensors? I've tried finding e23 e28 as well.

Jay
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Re: location of ABS fuse M635

Post by Stoffie » Tue Jun 02, 2020 7:14 pm

85MSteinway wrote:
Tue Jun 02, 2020 5:23 pm
plip1953 wrote:
Tue Jun 02, 2020 10:25 am

EDITED: I've now read the explanation of the test as you describe it (in that earlier link) and now understand the logic. So what I think this means is that you avoid a failure of something like our UK MOT by disconnecting all the sensors?
Now. anyone got a source for a rear wheel sensor? I'm having no luck. dealerships, Standard, Bosch, and Triscan are coming up with nothing. I've also tried finding it at local junk yards, with no luck there as well. Has anyone been able to use one from another vehicle with Bosch sensors? I've tried finding e23 e28 as well.

Jay
Not cheap, but might be worth a shot.

https://www.e28.nl/en/product/bmw-abs-s ... 121365275/
The M88/3 was all about power, no cats. At idle the raw fuel from the exhaust will make your eyes water like an old V-8 powered muscle car's exhaust did.

85MSteinway
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Re: location of ABS fuse M635

Post by 85MSteinway » Tue Jun 02, 2020 9:19 pm

Stoffie wrote:
Tue Jun 02, 2020 7:14 pm


Not cheap, but might be worth a shot.

https://www.e28.nl/en/product/bmw-abs-s ... 121365275/
Thanks buddy. I was just coming here to tell folks I found one from BWM of San Francisco. OEM at Stealership prices. Then saw you found these, which even at the exchange rate would be cheaper. Though I suspect shipping and customs might change that equation. Appreciate you finding it though. If I need another in the future I bookmarked that source. My heater valve went out on both my e24 within days of each other. hopefully that doesn't happen with sensor!

Jay
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85MSteinway
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Re: location of ABS fuse M635

Post by 85MSteinway » Tue Jun 09, 2020 2:59 pm

Ok, turns out BMW San Francisco was wrong. they finally called to tell me they didn't actually have them in stock. Thanks for nothing BMWSF. The link provided by Stoffie is actually for front wheel speed sensors. BUT, I spoke with Ivo Christov who runs that e28 site and they are getting rear sensors in later this week. I'm actually going to order a whole set to replace all of mine since even the ones that are working are rapidly falling apart.

Jay
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Re: location of ABS fuse M635

Post by Stoffie » Tue Jun 09, 2020 10:27 pm

Glad it's working out for you Jay!

Never occurred to me there would be a difference between front and rear abs sensors but apparently there is!
The M88/3 was all about power, no cats. At idle the raw fuel from the exhaust will make your eyes water like an old V-8 powered muscle car's exhaust did.

85MSteinway
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Re: location of ABS fuse M635

Post by 85MSteinway » Wed Jun 24, 2020 1:02 pm

Quick update. Ivo at 28.nl now has the rear sensors in stock. as well as the fronts. they have 30 in stock. Well, 28 now. Been a pleasure working with them.

Jay
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Re: location of ABS fuse M635

Post by ron » Wed Jun 24, 2020 1:56 pm

85MSteinway wrote:
Wed Jun 24, 2020 1:02 pm
Quick update. Ivo at 28.nl now has the rear sensors in stock. as well as the fronts. they have 30 in stock. Well, 28 now. Been a pleasure working with them.

Jay
The rear sensors are only for pre ‘86 cars. I’ve just recd. a pair which don’t fit my ‘87 car.

I’ve asked Ivo if he is getting the later ones made.
They are ALWAYS rustier than you thought!!!!!!
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85MSteinway
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Re: location of ABS fuse M635

Post by 85MSteinway » Wed Jun 24, 2020 5:08 pm

ron wrote:
Wed Jun 24, 2020 1:56 pm

The rear sensors are only for pre ‘86 cars. I’ve just recd. a pair which don’t fit my ‘87 car.

I’ve asked Ivo if he is getting the later ones made.
I didn't realize there was a difference. luckily mine is an 85, I guess. Is he getting them made post 86? What didn't fit for you? the sensor itself? or length?

Jay
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Re: location of ABS fuse M635

Post by ron » Wed Jun 24, 2020 5:34 pm

85MSteinway wrote:
Wed Jun 24, 2020 5:08 pm
I didn't realize there was a difference. What didn't fit for you? the sensor itself? or length?
The post '86 items are handed L & R. with fancy grommets. The ones I got from Ivo had no grommet or plug on the end.

I think that the difference is because the trailing arms are different between early and late.

These are pics of the later type of sensor.
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They are ALWAYS rustier than you thought!!!!!!
'85 M #228
'87 M #367
'88 High line.
'80 735i
'10 X5

85MSteinway
Posts: 53
Joined: Wed Oct 09, 2019 2:25 pm
Location: Texas

Re: location of ABS fuse M635

Post by 85MSteinway » Wed Jun 24, 2020 6:50 pm

I noticed the ones from Ivo didn't have the connector. I figured I'll just have to snip off my old connector and see if I can't brush up on my soldering skills. The old ones will have to be cut away if I want to salvage that fancy grommet anyway. Options are pretty slim, i'll post an update when I've received mine and installed.

Jay
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85 M635

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