Retrofit Cruise Control Diagnostics

Been out to recheck everything this morning.

Harness is spliced into the only Violet/Yellow wire that i can see.

Its also connected to the Black/Brown Pin 31 wire, which ive double checked.

On the Stalk Connectors, the Violet/Yellow runs at 12v, the Blue and Black/Brown 0v.

Should the Black/Brown have 12v as well? Thought this was the earth. If this is the cause, what else would this Black/Brown effect? Dash dimming, headlight movement all works, foglights dash lamps come on etc.

Ive a K-DCAN cable on its way and someone i know locally has INPA that ill be able to have a look on.
 
You should have two wires that run to the lcm and one to the dme is that what you have?

Where did you get the loom from ?
 
Yes 12v at the yellow purple, it should come from pin 27. Black brown is earth ftom pin 31. Use the multimeter to measure voltage between the yellow purple and black brown- which is what it sounds like you've done.

I'm sure there is more than one violet wire though as read of exactly this issue and it was tucked away!

If that is the case and you have power to the stalk, then your issue lies with the wire you have connected to the ECU.

Show us a picture of where you connected the blue wire to as well.
 
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bimmertune.com

BMW Z4 (E85/E86) cruise control retrofit

These instructions are for the Z4 cruise control wiring kit which can be bought here:Wiring | BMW Z4 cruise controlBimmertune wiring markingColor in instruction drawingsBlue/blackBlueViolet/YellowYellowBrown/blackBrownDepending if your car is left hand drive or right hand drive cruise control wirin
bimmertune.com bimmertune.com
 
Double check the connector that plugs into the cruise stalk has the wires in the correct order.

The E46 and E85 have the wires located differently. If whomever you bought the loom from makes them for both models they could have gotten confused and positioned them incorrectly.
 
ok, so ive got INPA now based on recommendations above. Lots more info than my OBD TOPDON can pull.

Clutch switch is working, and is triggering on and off, so if the brake switch on both circuits.

On one of the DME pages the clutch was showing having an error, probably where i was unplugging the switch on Saturday, but ive cleared the fault but cruise is still not operating.

This page below is im guessing cruise control, and nothing is coming out of it when pressing the stalk with ignition on.

Ill have a look now for PIN39 rather than the 4th pin in on the black connector bank.

1786375140434.png
 
IMG_6091.jpegIMG_6092.jpegHarness seems to be wired correctly, pins 1/2/4 all being used and matching the instructions from BMW

12v across the violet to brown wire with ignition on 2
 
Usel said:
The cruise stalk could be faulty, however pins 1 and 4 don't look like they are pushed home correctly in the cruise stalk connector.
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Seem to be in as far as they can go.

On the back side of the stalk there is a point to put a multimeter on and im getting 12v still from the violet to the brown.
 
Moose94 said:
Seem to be in as far as they can go.

On the back side of the stalk there is a point to put a multimeter on and im getting 12v still from the violet to the brown.
Click to expand...

Well they could be pushed in further, there's a tab to lift up, use a stanley knife blade. With the tab lifted up, push them in further and close the tab.

Screenshot_20260810_180437_Gallery.jpg

Screenshot_20260810_180426_Chrome.jpg
 
Usel said:
Well they could be pushed in further, there's a tab to lift up, use a stanley knife blade. With the tab lifted up, push them in further and close the tab.

View attachment 298707

View attachment 298706
Click to expand...
Aah I see what you mean.

Yeh I’ve given them push and they are fully seated. On the other side of the cruise control stalk connector point there’s a white bit that has exposed terminals and I’ve ran a multimeter across those and it’s showing 12v, so there’s power going through the system.

Anyone know if it’s possible to read a voltage or resistance from the blue wire?
 
Only other thing I can think of doing is finding another switch and giving that a try to rule out my switch before heading to bmw for warranty work
 
Moose94 said:
Only other thing I can think of doing is finding another switch and giving that a try to rule out my switch before heading to bmw for warranty work
Click to expand...
It's your only option now really. It's either the car, the loom or the cruise stalk.
 
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