Cruise control problems

Dukeisok

Regular Member
Joined
Oct 15, 2021
Points
9
I have a 2001 2.5i roadster with a 5 speed manual. The car is pristine with 36,000 original miles and everything on it was original and immaculate when I bought it. It worked great for a year or two then the cruise control stopped working. Occasional abs light but never stayed on. I checked the obvious things then took it to a well regarded European auto shop in town. They had it for 3 months and told me they tested every switch and wire in the system, replaced the ABS control box, then gave it back to me told me sorry, they couldn’t fix it.

took it to the other well regarded shop in town only to find they had heard of my car as the best bmw electrical guy had switched shops years ago and the first shop still calls him for help. They had it 3 months, rechecked everything, and told me the computer is saying the brakes are applied, the lights aren’t on and there is nothing they can do to get it to work. They sent me home

called me back 6 months later because another car came in with the same problem and they found a fix for it and wanted to try. They said there was an additional switch that was not on any wiring diagram that was the problem on the other car. They replaced mine and no luck.

now, still no cruise control, and three or four times, the car has jerked to the left while driving and sets a warning light for traction control off.

Any ideas what to do next? Bonus points if they tie the two issues together and are easy to fix 😀
 

NZ00Z3

Zorg Guru (IV)
Supporter
New Zealand Zeds
Joined
Dec 9, 2014
Points
158
Location
Timaru, New Zealand
Model of Z
3.0L, 2.8L, 2.0L Z3 Roadsters
How much of a DIY person are you? I ask up front because you'll need to be able to:
- Set up the INPA software on a windows laptop. Full instructions come with the software.
- Follow instructions on testing the cruise control system with INPA
- Read the wiring diagrams (attached)
- Delve into the car and change switches etc (usually in the most inaccessible places).

If you are up to the DIY, I can lead you through the testing etc.

You have not mentioned any warning lights being up or trouble codes in the engine DME, so the assumption is that there are not any. Is this correct?
 

Attachments

Dukeisok

Regular Member
Joined
Oct 15, 2021
Points
9
How much of a DIY person are you? I ask up front because you'll need to be able to:
- Set up the INPA software on a windows laptop. Full instructions come with the software.
- Follow instructions on testing the cruise control system with INPA
- Read the wiring diagrams (attached)
- Delve into the car and change switches etc (usually in the most inaccessible places).

If you are up to the DIY, I can lead you through the testing etc.

You have not mentioned any warning lights being up or trouble codes in the engine DME, so the assumption is that there are not any. Is this correct?
I diy enough to get myself into trouble ;) I’m more than willing to launch into this. I’ve rebuilt several older cars and can run a multimeter. I’ve never messed with BMWs much and have done most of my stuff on older gas cars and industrial diesels. My experience with computer gremlins is mostly on newer stuff with more mature OBD2. My son is a lanky 17 yo. He’d love nothing more than to hang upside down under the dash. I’m happy to work on it.

my dad runs an electrical engineering firm and I spent my summers growing up wiring and troubleshooting industrial equipment with him. My job currently is pretty far from that, but I think I can remember how to read a wiring diagram well enough to get me through a 12v system.

only light on the dash is “traction control off”

i just started looking at it last night and my son has the bidirectional scanner in his truck, so i haven’t read codes yet but planned to this evening

Thank you for the attachment. Very helpful
 
Last edited:

NZ00Z3

Zorg Guru (IV)
Supporter
New Zealand Zeds
Joined
Dec 9, 2014
Points
158
Location
Timaru, New Zealand
Model of Z
3.0L, 2.8L, 2.0L Z3 Roadsters
OK, lets get you set up with the INPA software. This means we both have the same set up and saves a lot of confusion.

It can be down loaded from here and comes with all the instructions. https://www.bimmerforums.com/forum/...tions-Experiences-Discussions-Experimentation

You will need to buy 2 leads:
- USB to OBD2. Like this one: https://www.ebay.com/itm/1255244078...irDBe5VKqf0ko4LNK0qb404EQ=|tkp:Bk9SR5SD2t22Zg
- OBD2 to 20 pin round connector. Like this one: https://www.ebay.com/itm/3550933088...Krrt4O4+88cm5beQdV+7ea0Esw==|tkp:BFBMsKTB3bZm

Both leads come together in a pack, like this one: https://www.ebay.com/itm/3871143541...iy6BdL0WhedL0c+NLn9+7bnezQ==|tkp:BFBMsKTB3bZm

Once you have the software set up and the leads on hand, we can start the testing.
 
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