My car's in Trouble Electrically!!

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mez
Posts: 5
Joined: Tue Oct 22, 2019 3:38 pm
Location: UK

My car's in Trouble Electrically!!

Post by mez »

[-o< Hi Guys

Ok I have a big problem on my 635!!
When I'm driving along I will suddenly lose drive and my auto gearbox loses drive, the selector switch on the box S/E/123 starts clicking erratically and it's like driving with Kangaroo juice VERY sporadic. I have removed both ECU's under the dashboard and cleaned with Contact cleaner, I have also replaced the Selector switch If i get the car started (not easy) and try to move it she keeps stalling. I have also replaced gearbox oil & filter,
My questions are
Is there a diagnostic port anywhere ?
Does the car see the new selector switch & would it need re-programming if I try a different ECU.
I am absolutely gutted it's playing up as I Have just spent a fortune getting all the bodywork done, so zero rust anywhere, all I want to do now is enjoy driving it as it"s been in Resto for the last 12 months.
Here's a pic of the Shark. Oh when I click insert image nothing happens.https://bigcoupe.com/phpBB3/download/fi ... w&id=31949

TIA Mark.
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Ralph in Socal
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Re: My car's in Trouble Electrically!!

Post by Ralph in Socal »

There’s electrical connections, solenoids and a pressure regulator in your transmission also. Those will have to be checked out and cleaned also

And there’s a control unit for the transmission also. I’m not very familiar with the fault conditions of that specific transmission so hopefully someone else can chime in

Seems very obvious that it’s an electrical issue so I would focus on those parts. A loose, broken or shorting wire can cause your issues

Ralph
There is a very fine line between "Hobby" and Mental Illness.

85 635csi Zinno Auto
84 528i Euro
83 635 Euro Arktik
81 528i Kastanien 5-speed
88 528e Bronzit (Granpa Car)
86 535i Auto (For Sale)
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mez
Posts: 5
Joined: Tue Oct 22, 2019 3:38 pm
Location: UK

Re: My car's in Trouble Electrically!!

Post by mez »

Ralph

Thanks for the reply I think your right definitely electrical as she shifted beautiful previously, car was a bit rusty at the bottom of the A pillar before so water could have maybe damaged the ECU's they did seem dry though. Only thing left to try is the bayonet plug on the box & give it a thorough clean.
Hopefully some others might have some idea.

Mark.
GRNSHRK
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Re: My car's in Trouble Electrically!!

Post by GRNSHRK »

Hey mez, I don't have any suggestions for your issues, but I am going to move your post to the mechanical/electrical forum, hopefully you will get more traction there [-o<
:mrgreen:
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86_6series
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Re: My car's in Trouble Electrically!!

Post by 86_6series »

I don't know what year you have but I picked 1986. This may be US only info but I'm sure the info might help.
PDF page 45 manual page 2460-4 starts AT troubleshooting, you may find a solution.

Good luck.

https://www.millerperformancecars.com/f ... Manual.pdf
86-635CSi
96-MB C220 SOLD
98-740i
71-Continental MK3
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