Retrofit Cruise Control Diagnostics

M

Moose94

Member
 Rugby
Hi All,

2006 (56) 3.0 SI Manual E85

Fitted the retrofit cruise control stalk+harness direct from BMW last night.

Harness connected to the headlight switch on Purple/Violet and Black/Brown. Blue harness ran all the way to the glovebox area, into the engine bay and into the 4th pin in on the Black DME connector in the junction box.

Cruise isnt working.

Any ideas what i can do to rule out any specifics on whats gone wrong?

Thoughts are 12v isnt coming into the switch, how would i test that, via the headlight switch, lights working/not?

Clutch position switch, from what i can gather does this only control the cruise on/off or should there be a rev function on clutch depress when on idle? Any other way of testing, car turns on without any pedals depressed but seems that is the norm.

Brake switch, brakes seem to work fine and no warnings or errors flagged on my obd2 reader.

BMW instructions state to update the ISSS module but reading online nobody seems to have needed to code it.

TIA
 
That I can think of, there are three things needed for the cruise to work:
- the correct signal from the brake light switch (brakes off)
- the correct signal from the clutch switch (clutch pedal up)
- a signal from the cruise control stalk

ISTA will not show you the stalk position, but if you use INPA you can read the status of the clutch and brake light switch, along with the position of the stalk (i.e. resume, cancel/accel/decel).

If you have access to INPA, I would connect it up, and read those values to find which isn't working.
 
Re check the light connections there are multiple colours similar

Best to go off the actual pins instead of colours on the lcm
 
TriggerFish said:
That I can think of, there are three things needed for the cruise to work:
- the correct signal from the brake light switch (brakes off)
- the correct signal from the clutch switch (clutch pedal up)
- a signal from the cruise control stalk

ISTA will not show you the stalk position, but if you use INPA you can read the status of the clutch and brake light switch, along with the position of the stalk (i.e. resume, cancel/accel/decel).

If you have access to INPA, I would connect it up, and read those values to find which isn't working.
Click to expand...
Is there a way of checking the pedal switches are operating correctly without inpa?
 
Moose94 said:
Is there a way of checking the pedal switches are operating correctly without inpa?
Click to expand...
Brake lights will be easy (and you've done those already). The clutch switch - maybe with a mutlimeter? It's probably a hall sensor, so I don't know how easy that will be to test in situ.
 
TriggerFish said:
Brake lights will be easy (and you've done those already). The clutch switch - maybe with a mutlimeter? It's probably a hall sensor, so I don't know how easy that will be to test in situ.
Click to expand...
It’s a right faff to get too so a multimeter might be tricky.

I’ll see if I can get a new switch and return it if it doesn’t fix the issue atleast.
 
Honestly, you'd be better off spending the £20 on a usb cable to get the diagnostic software IMO.

The cable will be useful in the future, and will help pin point the issue, rather than struggling in a contorted foot well for potentially no gain


Needs a Windows laptop
 
TriggerFish said:
Honestly, you'd be better off spending the £20 on a usb cable to get the diagnostic software IMO.

The cable will be useful in the future, and will help pin point the issue, rather than struggling in a contorted foot well for potentially no gain


Needs a Windows laptop
Click to expand...
Pretty sure I’ve a cable at home, just never managed to find a copy of inpa that wasn’t going to brick my laptop
 
That was my point really, the E85/86 doesn't have a cruise control light so it might actually be working fine. So above 30mph,push forwards and take your foot off the gas. Does it just slow back down?
 
This usually happens when people splice the wrong wires in the LCM as there are more than 1 of each.
As above double check pin numbers to make sure you've spliced the correct pins.

If you have, then drop your steering trim, disconnect the cruise stalk and using a multimeter, verify that you've got 12v across the two wires coming from the LCM.
If you do then it can only be a signal issue into the ECU at that point, so the blue wire.

It's literally 3 wires in the E85, you don't need INPA, power ground and signal.
 
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