Cruise control will not come on

[WisM]

I recently noticed the cruise control would not come when I pushed the switch. It has always worked fine up to now.
Today when I looked at this thread from the manifesto:
http://www.bimmerforums.com/forum/sh...under-the-dash
It dawned on me that I should check the brake switch.
When I checked the car, the brake lights were on whenever the key was on. OK that would fit the cruise symptom and ID a problem to fix. I grabbed a new switch from Autozone and installed that. Brake light problem fixed. Cruise control still inop.

Since the above seems to be the only cruise related topic in the manifesto, I searched many ways looking for another issue. The only thing I could come up with is the clutch position switch. Seems odd that both switches would be dead at the same time, but I guess I'll give that a shot unless someone has a better idea.

[cngizbleevng]

I can't really help you here other than to say that my cruise control sometimes works and sometimes doesn't. Same thing for the power softtop. There seems to be no rhyme or reason to it.

[MrDangles]

Cc runs of vacuum, no? Made the vacuum line has a tear? My cc is weird and will go wot sometimes. I think my car is trying to kill me.

[dghii]

Get this..besides my 99 M roady, I have an 00 Boxster S that I've owned for the last 7 years (wrong forum but it is a great car!). Early this spring, my CC wouldn't work. Turns out that if the CC indicator lamp fails, CC will not work. I replace the bulb and bingo, CC works just fine!

I know we have no indications of CC on our BMW's but it might b something really trivial. Good luck!

[Blacklane]

A lot of cruise control issues have been traced to the wire bundle that is next to the trunk hinge. The flexing there sometimes shorts out the brake light circuit. Sometime back, BMW issued a TIS to remove the center support cable-tie to help reduce the tension there.

[328 Power 04]

Cc runs of vacuum, no? Made the vacuum line has a tear? My cc is weird and will go wot sometimes. I think my car is trying to kill me.

No, it is a mechanical actuator, with a braided throttle wire running to the throttle body.

[jajou318]

In my coupe I lift the clutch pedal then I can turn on cc.

On my roadster haven't figured it out yet

[WisM]

A lot of cruise control issues have been traced to the wire bundle that is next to the trunk hinge. The flexing there sometimes shorts out the brake light circuit. Sometime back, BMW issued a TIS to remove the center support cable-tie to help reduce the tension there.

Good to know, but if my brake lights are now working properly after changing the switch, that should not be the case on mine. Right?

- - - Updated - - -

In my coupe I lift the clutch pedal then I can turn on cc.

On my roadster haven't figured it out yet

Tony, your coupe sounds like it could be clutch position switch related. Have you thought about changing the switch?

I ordered a replacement clutch position switch for mine. I'll report back here after I try that.

[TurboBimmer]

On mine the CC was working only intermittently. After a scan, I found that the RR speed sensor was defective. A wire had been crushed on the suspension arm by the previous owner. I fixed the wire and CC is functional since.
2000 Z3; 2.3

[amancuso]

On mine the CC was working only intermittently. After a scan, I found that the RR speed sensor was defective. A wire had been crushed on the suspension arm by the previous owner. I fixed the wire and CC is functional since.
2000 Z3; 2.3

I'm surprised it wasn't turning on the ABS and DSC light.

[danomite]

You need to do a scan and checked for codes. You've probably got some running error that is preventing the CC from being allowed to engage. So your car is actually probably trying NOT to kill....food for thought.

[WisM]

You need to do a scan and checked for codes. You've probably got some running error that is preventing the CC from being allowed to engage. So your car is actually probably trying NOT to kill....food for thought.

Checked that. No codes. Thanks though.

I also checked the trunk lid harness against the many photos posted of the typical damage. No damage to the harness.
I am hoping that the clutch position switch fixes it. Once I replace the clutch position switch and since the brake switch is good it is going to be down to the switch on the steering column or the cc unit itself. There is an outside chance it is some wiring gremlin, but since the system functioned correctly until recently, it seems less likely than a failed component.

We'll see what happens after I change the clutch position switch in a few days.

[z3forlife]

If you're clutch switch wasn't working the car wouldn't start due to interlock wouldn't it?

[Vinci]

My clutch pedal switch used to cause me problems with cruise control. Lifting the pedal took care of it before I fixed the issue.

Now my LED tail lights don't allow it to work. That's right. The tail light circuit is what cuts out the cruise control when you tap the brakes. Still haven't found a workaround for that one.

[WisM]

If you're clutch switch wasn't working the car wouldn't start due to interlock wouldn't it?

I thought that when I started troubleshooting this too.
There are two switches. The start interlock is one.
The clutch position switch for the cc is a separate switch.

- - - Updated - - -

The tail light circuit is what cuts out the cruise control when you tap the brakes. Still haven't found a workaround for that one.

actually according to the wiring diagrams, the brake light switch AND the clutch position switch both disengage the cc. What could possibly go wrong there.

[deni2s]

I can't really help you here other than to say that my cruise control sometimes works and sometimes doesn't. Same thing for the power softtop. There seems to be no rhyme or reason to it.

Power softtop issue usually is the microswitch on top of your left shoulder. In your case, most probably that is the brake switch - it is used for cc and for power softtop.

- - - Updated - - -

If you're clutch switch wasn't working the car wouldn't start due to interlock wouldn't it?

No, the car starts even without clutch switch.

[WisM]

No, the car starts even without clutch switch.

Not on my car.
Perhaps the non-US cars don't have the start interlock switch?

[TurboBimmer]

I'm surprised it wasn't turning on the ABS and DSC light.

Yes, you're right. The ABS light was ON. The DSC light wasn't, but I think it is burned since it never came ON even after the repair.

The reason I forgot about the ABS light is because the ABS light was solid ON, but the CC was still working once in a while. Bizarre.

[sjdennis]

Try replacing both rear brake light bulbs. This worked for me and if it doesn't work your not out much.

Dennis

[WisM]

Try replacing both rear brake light bulbs. This worked for me and if it doesn't work your not out much.

Dennis

On mine the brake lights are working fine since I replaced the brake light switch.
If the cc still doesn't work after I replace the clutch position switch, I'll give this a try.
Like you said, won't cost much to try it.

[BimmerBreaker]

I could easily be wrong here but I think when the clutch switch fails it fails "open" so the car will still start but functions that are disabled with the clutch pressed (Cruise Control notably...) will not work.

[WisM]

I could easily be wrong here but I think when the clutch switch fails it fails "open" so the car will still start but functions that are disabled with the clutch pressed (Cruise Control notably...) will not work.

My car does not start unless I push the clutch in, so that function is working. Everything I have looked at shows two separate switches on the clutch.
The one on the fwd side of the clutch arm is identified as the starter interlock switch.
The one on the aft side ( next to the brake light switch) is called the clutch position switch or cruise control cutout switch depending where you look. That is the one I'm replacing when the new one I ordered shows up.

As has been said on this forum many times, troubleshooting electrical issues through the Internet is tough.

It does not help when there are so many different configurations for these cars as well as different terminology used for the same thing from some of the regular information sources. I've spent a lot of time experiencing that on this topic since I started this.

[rf900rkw]

There are two different clutch switches, S235 for the starter, S32 for the CC.

The way the system is wired, LED brake light bulbs will disable the CC.

[WisM]

There are two different clutch switches, S235 for the starter, S32 for the CC.

The way the system is wired, LED brake light bulbs will disable the CC.

Thanks for confirming the two functions are separate switches. No LEDs on my car.
I'm hoping the replacement cc cutout switch fixes it. I have a couple of long drives I want to do. It would be nice to have the cc working for the just getting there part.

[Vinci]

There are two different clutch switches, S235 for the starter, S32 for the CC.

The way the system is wired, LED brake light bulbs will disable the CC.

Do you have some more information about this? I rebuilt my tail light trays and installed LEDs, and like you said, my cruise no longer works.

I assume it has something to do with switching the ground, as I also find that my running lights will flash with the turn signal if they aren't explicitly activated.