Unidentified wiring harness

[pchotard]

Hi

When i bought my 91 850i individual one year ago, i saw an unplugged harness in the engine bay, driver side (LHD), touching the exhaust pipe.
The female round connector and the wires are partially meld,the wiring harness is composed of 7 wires.

There is no male round connector in the area, is somebody knows the purpose of this wiring harness ?

For information, this car is equipped with EDC, ASC-T, servotronic and AHK.

PXL_20220115_150236063.jpgPXL_20220115_150322011.jpgPXL_20220115_150347524.jpgPXL_20220115_150402110.jpg

[revtor]

That's a mystery connector... According to the diagrams there are only 4 of such round 7-pin connectors and they are all for the headlights (X128 left FTP, X130 left popup, X135 right popup and X137 right FTP). Your connector looks like one of those but the wire colors do not match with the diagrams. Nevertheless, can you check whether you already have 4 such connectors for the headlights?

Update: There are actually 2 more of such connectors in case of a M70/S70 V12 engine: I forgot to list X6216 (left mass air flow sensor) and X6226 (right mass air flow sensor).

[pchotard]

That's a mystery connector... According to the diagrams there are only 4 of such round 7-pin connectors and they are all for the headlights (X128 left FTP, X130 left popup, X135 right popup and X137 right FTP). Your connector looks like one of those but the wire colors do not match with the diagrams. Nevertheless, can you check whether you already have 4 such connectors for the headlights?

Yes i confirm, there are also 4 other 7-pins round connectors for the headlights.
When i will have time, i will follow the wiring harness to find from which place it comes.

[Timm]

There is another round connector for the heater valves / auxiliary water pump at the firewall. It can just be seen below at the lower left-hand side of this picture - it is secured to the plastic bracket:

[pchotard]

There is another round connector for the heater valves / auxiliary water pump at the firewall. It can just be seen below at the lower left-hand side of this picture - it is secured to the plastic bracket:

Yes, but this round connector is a 9-pins.

[Timm]

Your picture shows a 7-pin connector doesn't it?

Fullscreen capture 16012022 222901.bmp.jpg

[CD05001CIA]

Your picture shows a 7-pin connector doesn't it?

Timm that was my first thought also....

RotaryLatch.jpg


These connectors have a rotary latch that can be released to free the terminals and pull the terminals out the back to replace the shell.

I'd do it one at a time to keep from mixing up the positions.

[pchotard]

Your picture shows a 7-pin connector doesn't it?

Fullscreen capture 16012022 222901.bmp.jpg

Yes my picture shows a 7-pin.
But your picture on post 5 , shows a 9-pin.

[pchotard]

Hi All

Some news about the mystery round 7-pins connector located in my 1991 850i engine bay.
As explained above, in my 850i engine bay, there are 5 round 7-pins connectors whereas only 4 are documented in the E31 Electrical Troubleshooting Manual (these have been listed by Revtor in post #2)

As described in post #1, my 850i is one of the rarest which is equipped with AHK (four steering wheel system).
Only 1732 E31 were equipped with AHK as indicated here https://e31wiki.org/wiki/Active_Rear_Axle_Kinematics

I took time to check the harness and found that at least 2 wires are connected to the AHK control unit located in the trunk (i didn't check the 5 others wires)
For reference here are the wire's color:
yellow
black / white stripe
grey / pink stripe
yellow / green stripe
black
grey
red / violet stripe

In the 1991 E31 Electrical Troubleshooting Manual, AHK is not documented, but finally i found some AHK information in the 1994 E31 Electrical Troubleshooting Manual.

My first though is this round connector should be a diagnostic port.
If someone else has more information about this connector, i will appreciate ;-)

Thanks

[revtor]

pchotard: I was wrong about only 4 round 7-pins connectors in the electrical troubleshooting manual (ETM). There are actually 6 in case of the M70/S70 V12 engine. I forgot to list X6216 and X6226 (left/right mass air flow sensors). However, just like the other 4 mentioned before these are not related to your mystery connector. I really can't find more 7-pin round connectors in the available documentation. One issue is that you have a '91 euro E31 whereas the '91 ETM applies to US E31. Sadly there is no (publicly available) German ETM for model year '91 (only '94/'95/'96). It is possible the connector is not present in US E31 but is in early euro E31.

What is strange is that there is no brown or brown/orange wire (always ground). A diagnostic port without ground does not make sense. Maybe black is ground but that is extremely rare in BMW wiring.

The grey wire is quite light in your images so it could be white. Grey/pink could be white/pink but pink can be mixed up with violet so it may be grey/violet or white/violet.

Most wire color combinations are not unique and occur for different purposes but a black/white stripe wire often indicates a road speed signal (sent by EKM and consumed by AHK, EDC, DME,...). Yellow and yellow/green are seen mostly in the headlight wiring and certainly nowhere near AHK. Which wires did trace to the AHK module?

[pchotard]

Some update about this connector.

I traced all wire from this connector and 3 of them goes to the AHK module (on the upper left white connector), the 4 others goes to an apparently unused connector near the AHK module.
This connector is currently unplugged, this is the one located at the bottom right of the below picture.

PXL_20220728_144849255.jpg

To sum-up :
Following wires goes to the unplugged black rectangle 12-pins connector.
- yellow
- grey
- yellow/green
- black/white

Following wires goes to the white upper left rectangle 12-pins connector.
- black
- red/violet
- grey/violet

[pchotard]

i created a dedicated thread about AHK module with some pictures : https://www.bimmerforums.com/forum/s...es-for-curious

[revtor]

Thanks for the update. Very interesting.

I wonder, since you have a '91 850i you might have one of the first E31 equipped with AHK (it was not yet available at launch). These might be some leftovers from factory testing.

Can you inquire with Reinhard at 8coupe.com (or directly at 8er.org if you are a forum member there) how many E31 before yours had AHK?

[pchotard]

Hi Revtor

I got an answer from Reinhard, mine is an early 850i with AHK:

Hello Patrice,

thanks for the message - interesting

Your CB4656 is the first M70 Auto which has S237 in the option sheet!

It is not the first M70 with S237 though. There were 3 M70 Manual cars
before yours.

These are:
CB12041 15-Mar-90
CB12045 7-May-90
CB12605 22-Jan-91

A long time ago I saw the red 850 convertible in Munich which was based
on a prototype VIN (not CBxxxxx) - this one also has AHK installed
(build date likely early 190).

Here is a breakdown of M70´s with S237:
220 Auto LHD
77 Manual LHD

124 Auto RHD
7 Manual RHD

If you would like to send a few pictures of your car I can add this to
the archives.

Best regards
Reinhard
8Coupe.com