WTB - Diagnostic cap with tether for '88 M5 E28

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gsidman
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WTB - Diagnostic cap with tether for '88 M5 E28

Post by gsidman »

The parts houses keep sending me the wrong part. They are all too big, obviously from later cars. Does anyone have a spare in good condition, or the proper part number for the '88 M5 ??
Shawn D.
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Beamter
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Re: WTB - Diagnostic cap with tether for '88 M5 E28

Post by Shawn D. »

Are you going by what they supply on site, or have you looked up the number in the ETK (i.e. at RealOEM.com)?
DFWTX85
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Re: WTB - Diagnostic cap with tether for '88 M5 E28

Post by DFWTX85 »

Do the other E28's not use the same cap? If they all use the same one then I saw these new on eBay last week.
gsidman
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Joined: Mar 26, 2021 2:51 PM
Location: California

Re: WTB - Diagnostic cap with tether for '88 M5 E28

Post by gsidman »

I have been going by the fit list on the suppliers sites as I can't find a part number on realOEM.com. Maybe I am not looking at the right sub-section, but I have been all over realOEM.com with no luck. Apparently, there are more than one part numbers, but they all lead to the wrong part. I am sure there are folks out there better at finding a part number. Any help would be appreciated.
DFWTX85
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Re: WTB - Diagnostic cap with tether for '88 M5 E28

Post by DFWTX85 »

gsidman wrote: Jun 11, 2021 11:44 AM I have been going by the fit list on the suppliers sites as I can't find a part number on realOEM.com. Maybe I am not looking at the right sub-section, but I have been all over realOEM.com with no luck. Apparently, there are more than one part numbers, but they all lead to the wrong part. I am sure there are folks out there better at finding a part number. Any help would be appreciated.
Try this and see how it compares to what you've already seen....

https://www.ebay.com/itm/293887072260?

https://www.ebay.com/itm/273259503060?
gsidman
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Joined: Mar 26, 2021 2:51 PM
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Re: WTB - Diagnostic cap with tether for '88 M5 E28

Post by gsidman »

Thanks for the links. Both won't fit. All the eBay caps I have seen so far are for later model cars or not right for the '88 M5. The mystery continues....
John in VA
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Re: WTB - Diagnostic cap with tether for '88 M5 E28

Post by John in VA »

It's odd that they don't fit, unless as usual BMW has recommissioned the part & the vendors did something wrong! The E12, 21, 23, 24, 28 & 30 all used that cap. BMW part # was 12521273101; now 12521286052.
RonW
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Re: WTB - Diagnostic cap with tether for '88 M5 E28

Post by RonW »

A wild guess: In the rest of the world, the '88 5-series was the E34, which used a screw-on cap. If you ask for a cap for an '88 5-series, they might send you that. Ask for a cap for an '87 instead.
gsidman
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Re: WTB - Diagnostic cap with tether for '88 M5 E28

Post by gsidman »

Thanks for the replies. However, part numbers 12521273101; now 12521286052 refer to the cam sensor cover, not the engine room diagnostic port cap. The '88 M5 is an E28, and obviously the diagnostic port is different from the other series 5 cars of the era. All series 5 M5 are designated as 1988 cars, regardless of when they were manufactured. All the caps I see on eBay are incorrect. I have one in hand and it clearly is too big, the tether is too large, it has a large center plastic prong and the wrong pin configuration. Searches on ECS, Turner and other sites all try to sell me the wrong cap. The mystery continues.......
kojo96
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Location: Pleasanton CA

Re: WTB - Diagnostic cap with tether for '88 M5 E28

Post by kojo96 »

Maybe post an image of your diagnostic port so we can see what it looks like, may help you get results.
gsidman
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Location: California

Re: WTB - Diagnostic cap with tether for '88 M5 E28

Post by gsidman »

You can see that the pin outs for this plug don't match with the caps one sees on eBay. It is starting to appear that this M5, built in November 1986 and purchased in March 1987, has a plug unique to the series. VIN WBSDC930XJ2791029

https://www.dropbox.com/s/oqu5lbaesrujm ... g.jpg?dl=0]
kojo96
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Re: WTB - Diagnostic cap with tether for '88 M5 E28

Post by kojo96 »

gsidman wrote: Jun 14, 2021 4:09 PM You can see that the pin outs for this plug don't match with the caps one sees on eBay. It is starting to appear that this M5, built in November 1986 and purchased in March 1987, has a plug unique to the series. VIN WBSDC930XJ2791029

https://www.dropbox.com/s/oqu5lbaesrujm ... g.jpg?dl=0]
Looks like the same as the e28 series diagnostic plugs/ caps are the same.
RonW
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Re: WTB - Diagnostic cap with tether for '88 M5 E28

Post by RonW »

OK, there's something weird going on. All of a sudden RealOEM doesn't show that part as pertaining to a 535i or an M5:
https://www.realoem.com/bmw/enUS/showpa ... Id=12_0318. Note that the part in question (#9) is greyed out.

It is shown as part of a USA 533i, but not a USA 535i or an M5:
https://www.realoem.com/bmw/enUS/partxr ... series=E28.

In ECS Tuning's web site, the part is listed as a "Cam Sensor Cover": https://www.ecstuning.com/b-genuine-bmw ... 521286052/. And again, it shows it as part of a 533i but not a 535i.

It actually is a cam sensor cover, in that the top dead center sensor (unused by the car's electronics, and not even connected to them) is connected to the diagnostic connector.

Nonetheless, I have a spare, and it's clearly stamped 1286052. (BMW's practice is to stamp a partial part number if the full one doesn't fit.)
Blue Shadow
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Re: WTB - Diagnostic cap with tether for '88 M5 E28

Post by Blue Shadow »

1) ecs tuning has the wrong description of the item 12521273101 which is not a cam sensor cover but a diagnostic plug cover

2) the pinout is backwards, it is mirrored so it doesn't look right. Note the bottom row of 4 has the second one higher and the plug has the third one higher. Similar with other pins. Something those of us that have had these cars for decades found out years ago as there really are only two diagnostic plug covers that fit. the original red and the replacement black for all these cars.

3) it is the right part for your car.
gsidman
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Joined: Mar 26, 2021 2:51 PM
Location: California

Re: WTB - Diagnostic cap with tether for '88 M5 E28

Post by gsidman »

Mystery solved...!! RonW and Blueshadow provided the needed confirmation that ECS and other parts houses have this part somewhat confused. They list it as a cam sensor cover, but it covers the diagnostic plug. I just bought it on ECS, but right on the same page with the part, ECS tells me that it does not fit my car. My thanks to everyone for helping figure this one out.
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