I drive a 325e (US-spec) from 1984. It is fitted with a cruise control unit which actually didn't work at all when I first got it, simply got no response when using the CC control unit in my steering column. However after a few weeks of owning the car, I noticed that it would sometimes keep the gas pedal down even when I put down my clutch. The weird part is that when I press the brake while CC is on, it doesn't disable the CC (seemingly). I assume this is a broken clutch switch.
So for now I completely disabled the CC cable completely. I can put it back on to do some more testing (disabled it because I had to drive some distance).
If anyone has tips on things to try or look at so I can narrow down the issue, any advice is very welcome. I'll start trying things ASAP!
P.S. Also may be noteworthy that my check-light for the brake lights is always on when I start the car, and disappears after ~30 seconds.
Thanks!
Re: Cruise control seems to get stuck
Posted: Sat Mar 28, 2020 10:28 pm
by Cloggy Saint
Can't help with the cruise issue but the check light for the brake lights will stay lit until you press the brake pedal, assuming the brake lights work.
Re: Cruise control seems to get stuck
Posted: Sun Mar 29, 2020 10:19 am
by Kalimsnor
Thanks Cloggy Saint, you're right. It turns off when I use my brakes once. Good to know it's not a faulty sensor!
So today I did some more digging, here's some things I found.
- I re-connected the CC throttle cable back up and did a test-drive. Couldn't get the CC to kick in, which I kind of expected. When it happened previously it was always at (seemingly) random moments.
- I double-checked if the cables coming from the CC buttons was connected properly. It is: https://i.imgur.com/sH0yERJ.jpg
- I went looking for the clutchswitch. I think I found it, but it's completely unconnected and way out of reach of my clutch pedal. I found this video (NOT MINE) on YouTube which shows a white clutch switch:
However, I couldn't find something like this in my car. What I *did* find was this switch: https://i.imgur.com/8i7mWss.jpg (read: the photo is upside down - the other switch is the brake switch, which I replaced about a month ago). As you can see the red part is completely out of reach of the pedal, and there is not even a cable connected.
- I found three cables that were not connected to anything. I'm pretty sure the first one is supposed to go on my clutch switch: https://i.imgur.com/Cn0tEGI.jpg https://i.imgur.com/Oqx6Ouz.jpg https://i.imgur.com/MrSrfNc.jpg
Are the other two related to the cruise control or not at all?
So, what I did is take out the clutch switch, connect it to that first cable (https://i.imgur.com/Cn0tEGI.jpg) and drive a bit. While pressing it down I tried to enable my cruise control but still had no luck.
Re: Cruise control seems to get stuck
Posted: Sun Mar 29, 2020 11:44 am
by flybynite
Have a look at the wiki page on here about cruise control, it has the wiring and some fault finding tips.
Looks like the brown/green is the wire the clutch switch breaks
Thanks. I already had checked this before posting, as well as these forums. So far I'm still clueless on where to look :-/
Re: Cruise control seems to get stuck
Posted: Mon Mar 30, 2020 10:53 pm
by Brianmoooore
The clutch switch connector you show in your pic. has two green/red wires. Identify which is the one that goes to the green/red on the actuator, then connect a piece of wire to the green/red at the plug.
Connect another piece of wire to a good body earth, then strip about 15mm of insulation from the free ends f both wires and lightly twist them together.
Drive the car, engage the cruise control and see if it works. Note that the cruise control will NOT disengage if you push the brake or clutch, so great care is required. Have the lightly twisted join in the wire in your hand, and pull them apart. This should disengage the cruise control.
Repeat the exercise until you are certain the cruise is engaging when the wires are together and switched on, and disengaging when the wires are pulled apart. Remember at all times that switching off the key will stop the car accelerating, but don't pull out the key, or the steering will lock.
The clutch switch connector you show in your pic. has two green/red wires. Identify which is the one that goes to the green/red on the actuator
It has two green/red wires indeed. The cable wasn't connected so I'm not sure which way it's supposed to be on there. By identifying which is which, do you mean I have to follow the cable to the hood where the CC unit is located, to see which side it connects there?
then connect a piece of wire to the green/red at the plug.
Sorry I don't fully understand this, English is not my first language. Where would this wire go when connected to the plug? And is the plug connected to the clutchswitch at this point or not?
Drive the car, engage the cruise control and see if it works. Note that the cruise control will NOT disengage if you push the brake or clutch, so great care is required. Have the lightly twisted join in the wire in your hand, and pull them apart. This should disengage the cruise control.
Repeat the exercise until you are certain the cruise is engaging when the wires are together and switched on, and disengaging when the wires are pulled apart. Remember at all times that switching off the key will stop the car accelerating, but don't pull out the key, or the steering will lock.
I have a long strip of road real close to my house with barely any cars luckily. But thanks for the advice, especially for the steerlock.
The clutch switch connector you show in your pic. has two green/red wires. Identify which is the one that goes to the green/red on the actuator
It has two green/red wires indeed. The cable wasn't connected so I'm not sure which way it's supposed to be on there. By identifying which is which, do you mean I have to follow the cable to the hood where the CC unit is located, to see which side it connects there?
Yes, use a meter on the continuity range (buzzer) to find which of the green/reds is the one you want. You will blow a fuse later if you get it wrong
then connect a piece of wire to the green/red at the plug.
Sorry I don't fully understand this, English is not my first language. Where would this wire go when connected to the plug? And is the plug connected to the clutchswitch at this point or not?
The plug is not connected to the clutch switch, and the wire goes to the wire you identified as going to the control unit.
Drive the car, engage the cruise control and see if it works. Note that the cruise control will NOT disengage if you push the brake or clutch, so great care is required. Have the lightly twisted join in the wire in your hand, and pull them apart. This should disengage the cruise control.
Repeat the exercise until you are certain the cruise is engaging when the wires are together and switched on, and disengaging when the wires are pulled apart. Remember at all times that switching off the key will stop the car accelerating, but don't pull out the key, or the steering will lock.
I have a long strip of road real close to my house with barely any cars luckily. But thanks for the advice, especially for the steerlock.
Re: Cruise control seems to get stuck
Posted: Sun Nov 08, 2020 12:15 pm
by Kalimsnor
So, I brought the car into an E30 specialist. He connected everything up properly and thinks the problem is that I have a gauge cluster from a 325i even though my car isa 325e. This causes the CC to be unable to read the actual speed the car is going, according to him. So he thinks I need a cluster from an eta to get it to work. Anyone got their 2 cents on this?
Re: Cruise control seems to get stuck
Posted: Sun Nov 08, 2020 1:39 pm
by Brianmoooore
I think your E30 specialist may not be quite the specialist he claims to be.
I think your E30 specialist may not be quite the specialist he claims to be.
Hmm, that's slightly worrying seeing as what he's already done for me. Are you telling me the cluster is completely unrelated to CC unit? Because everything is now connected properly according to him.
Re: Cruise control seems to get stuck
Posted: Mon Nov 09, 2020 1:25 pm
by Brianmoooore
The CC takes a road speed signal from the instrument cluster, but there's no difference in the basic cluster between one for a 325i nd one for a 325e. Road speed signal is road speed signal.
Re: Cruise control seems to get stuck
Posted: Mon Nov 09, 2020 1:38 pm
by Brianmoooore
I've just looked back at your OP.
Brake check light should come on with the ignition and not go out at all until you press the brake pedal. If it's going out without you touching the brakes, then there's possibly a problem with the brake light switch (or adjustment), and of course, the brake light switch is part of the CC control.
Pull both wires off of the clutch switch for now and connect reliably together. This will help eliminate it from the suspect list. you can drive it with CC normally like this, as long as you make quick gearshifts.
The CC takes a road speed signal from the instrument cluster, but there's no difference in the basic cluster between one for a 325i nd one for a 325e. Road speed signal is road speed signal.
Even when considering the 325e cluster would be in MPH (the car is USA-spec) and my current 325i cluster is in KMH?
I've just looked back at your OP.
Brake check light should come on with the ignition and not go out at all until you press the brake pedal. If it's going out without you touching the brakes, then there's possibly a problem with the brake light switch (or adjustment), and of course, the brake light switch is part of the CC control.
Pull both wires off of the clutch switch for now and connect reliably together. This will help eliminate it from the suspect list. you can drive it with CC normally like this, as long as you make quick gearshifts.
The brake check light works as you described, so I don't think that's the suspect. I like your idea of directly connecting the clutch switch cables to see if the CC engages at all, I'll report back when I have tried this! (might take a few weeks, I'm preparing the car for winter storage)
Even when considering the 325e cluster would be in MPH (the car is USA-spec) and my current 325i cluster is in KMH?
That's just the printing on the dial and the gears that drive the odometer. The electrical signal doesn't do metric or imperial.
The cruise control uses a fairly simple ECU. It simply compares the voltage of the road speed signal to one held in a temporary memory, and drives the throttle open if the former is less than the latter, or drives the throttle closed if the former is more than the latter - two diodes connected between the two voltage sources, one facing each way. Current flowing in a diode switches on a voltage source. Reversible DC throttle motor connected between the two voltage sources.
Re: Cruise control seems to get stuck
Posted: Sun Nov 29, 2020 8:39 pm
by Kalimsnor
Hi. I've connected the two green/red cables together that were normally connected to the clutch switch. Nothing happens when driving ~80km and attempting to engage the CC.
I'm very open to more idea's on how to rule out other faults!
Re: Cruise control seems to get stuck
Posted: Sun Nov 29, 2020 8:50 pm
by kdevitt
Mine was working after I fitted it, before suddenly stopping. I thought it might have been the stalk or clutch switch - but there was dry solder within the actuator itself causing the issue.
Mine was working after I fitted it, before suddenly stopping. I thought it might have been the stalk or clutch switch - but there was dry solder within the actuator itself causing the issue.
Mine was working after I fitted it, before suddenly stopping. I thought it might have been the stalk or clutch switch - but there was dry solder within the actuator itself causing the issue.
I got a friendly genius to open it up - that is the actuator that was opened up. There's a cog which is used to control the motor which pulls on the cruise throttle cable - it wasn't engaging. He checked the signals going to the cruise control ECU as well - and that all worked fine (stalk / brake switch / clutch switch)
Mine was working after I fitted it, before suddenly stopping. I thought it might have been the stalk or clutch switch - but there was dry solder within the actuator itself causing the issue.
I got a friendly genius to open it up - that is the actuator that was opened up. There's a cog which is used to control the motor which pulls on the cruise throttle cable - it wasn't engaging. He checked the signals going to the cruise control ECU as well - and that all worked fine (stalk / brake switch / clutch switch)
Feels a little bit like my last resort if I can't get it to work with any other ways. I'm hoping Brian might have some more tips on how to rule out other causes, before opening the whole unit itself!
Re: Cruise control seems to get stuck
Posted: Sun Dec 06, 2020 9:19 pm
by Brianmoooore
Circuit diagram is here: http://www.autolib.diakom.ru/CAR/BMW/19 ... /fig07.pdf
You can follow the wires around, and work out what voltages should be where. For instance, check that there's 12 volts + on pin 1 of the ECU, and that 12 volts+ appears on pins 1, 3, 4 and 5 of the control switch when you move it in the positions shown on the circuit diagram.
Re: Cruise control seems to get stuck
Posted: Mon May 10, 2021 2:53 pm
by Kalimsnor
Fixed! Very happy with my now-working CC unit!
I will respond to this post to explain what the problem was, in case anyone else finds themself having CC issues. As it turns out, my original post was incorrect. The CC unit didn't sometimes kick in, I think this was either related to my faulty ICV (already replaced a while ago) or having the CC throttle cable tightened too much.
Mine was working after I fitted it, before suddenly stopping. I thought it might have been the stalk or clutch switch - but there was dry solder within the actuator itself causing the issue.
You were definitely on the right track for my problem as well! I found someone nearby my house who did a lot of retrofitting CC units in E30s. We took apart the actuator and as it turned out, the little motor inside the actuator was complety missing. We replaced it with a CC unit from an E24 (or E28, not sure) and everything is working flawlessly for the first time! I couldn't be happier.
Now perhaps someone here can tell me what they think caused someone to remove this little tiny electrical motor. Perhaps it was draining electricity? That's the only semi-explanation I have, but it doesn't really make sense. It would be a lot easier to just take off some of the cables.
However after a few weeks of owning the car, I noticed that it would sometimes keep the gas pedal down even when I put down my clutch. The weird part is that when I press the brake while CC is on, it doesn't disable the CC (seemingly). I assume this is a broken clutch switch.
I wonder if something is sticking in the throttle linkage, making it stick partly open, and the previous owner, like you, assumed it was the CC doing it, so removed the motor. Disconnecting the cable would have been easier, but there's some strange people around.
However after a few weeks of owning the car, I noticed that it would sometimes keep the gas pedal down even when I put down my clutch. The weird part is that when I press the brake while CC is on, it doesn't disable the CC (seemingly). I assume this is a broken clutch switch.
I wonder if something is sticking in the throttle linkage, making it stick partly open, and the previous owner, like you, assumed it was the CC doing it, so removed the motor. Disconnecting the cable would have been easier, but there's some strange people around.
It seems like it was solved after I replaced my ICV a little while ago. The cable seems to be fine now, I didn't replace or change it.
Re: Cruise control seems to get stuck
Posted: Tue May 11, 2021 10:54 am
by Brianmoooore
An ICV sticking open would feel exactly like the throttle sticking partly open, so quite possible.
