M52TUB25 Cruise Control Retrofit Challenges

[staggerwing17]

Hello All!
I purchased a 1999 BMW Z3 a few months ago and after reading through this and other forums I concluded that retrofitting a cruise control should not be a difficult job. In particular, I found this article well done and extremely helpful:
https://zroadster.org/articles/bmw-z3-m54-cruise-control-retrofit.25/

After reading many, many posts, I became confident that the M52TU in my Z3 was, at least for the cruise control function, fly by wire. Yes there is a throttle cable but there is apparently also a motor at the throttle body that handles ASC and Cruise Control functions (and can even override the cable). I determined the fly by wire status of my car by reading the following 2 posts:
https://zroadster.org/threads/retrofit-cruise-control.13617/#post-218627
and
https://zroadster.org/threads/retrofit-cruise-control.13617/#post-218680

My FGR Interface Module arrived today (several days early!) so I quickly disassembled the lower left under dash, knee guard and steering column cover. With the PC in the passenger seat I simply followed Brian H's instructions. All went very easily. A test drive, however, showed that I had no cruise control functionality.

I checked the fuse at position 46 and it is good. So some questions:

1. The fuse at position 46 is labeled in the fuse box cover as "Cruise Control (Tempomat)." I thought the Tempomat label was for the actuator/Bowden cable version of cruise control? Is the label perhaps an errant carryover since my M52TU was a transition model from actuator/cable to fly by wire?
2. Does the fact that there is a 3 pin cable in the wiring loom above the pedals that exactly fit the FGR interface confirm that I do in fact have fly by wire?
   
3. The manufacture date is 3/99. Yet the clutch switch has 3 wires. Does this put it beyond the first version of fly by wire?
4. ASSUMING I do have fly by wire, what are the next steps to troubleshooting?

I have included images of my work so far. If I have done something fundamentally stupid, please let me know. Otherwise, any help would be appreciated!

 

[NZ00Z3]

Do you have a wiring diagram for your car? Attached is the one I'm using for your car. Pages 6571.0.02 and 03. Its for cars produced from 4/99 to end of run. It matches your car with the 3 wire clutch switch.

1) Fuse 46 feeds one side of the brake switch. Fuse 13 the other side of the brake switch. Fuse 26 is the main cruise control feed. Fuse 43 feed the clutch switch.

2) Yes you are "Fly by wire" for cruise control.

3) 3 wires means its a hall effect switch, which lines up with the wiring diagrams.

4) Next steps in trouble shooting are:
- check all fuses listing in 1) above.

- If you have a scanner, look for codes. Often the brake switch sets a "BTS implausible" code saying the brake switch is faulty. This is the most likely problem for you. The brake lights will work but the switch side feed from Fuse 13 has broken. If you don't have a scanner, then its a multi-meter job to test out both sides of the brake switch.

- Test out the Clutch switch with the multi-meter. Being a USA car you probably have to push the clutch to start the car. Testing this feature will test the clutch switch.

Hope all of this helps.

Regards

Murray

 

[staggerwing17]

Do you have a wiring diagram for your car? Attached is the one I'm using for your car. Pages 6571.0.02 and 03. Its for cars produced from 4/99 to end of run. It matches your car with the 3 wire clutch switch.

1) Fuse 46 feeds one side of the brake switch. Fuse 13 the other side of the brake switch. Fuse 26 is the main cruise control feed. Fuse 43 feed the clutch switch.

2) Yes you are "Fly by wire" for cruise control.

3) 3 wires means its a hall effect switch, which lines up with the wiring diagrams.

4) Next steps in trouble shooting are:
- check all fuses listing in 1) above.

- If you have a scanner, look for codes. Often the brake switch sets a "BTS implausible" code saying the brake switch is faulty. This is the most likely problem for you. The brake lights will work but the switch side feed from Fuse 13 has broken. If you don't have a scanner, then its a multi-meter job to test out both sides of the brake switch.
- Test out the Clutch switch with the multi-meter. Being a USA car you probably have to push the clutch to start the car. Testing this feature will test the clutch switch.

Hope all of this helps.

Regards

Murray

Wow Murray thank you for taking your time to assist! I am grateful and indebted for your expertise and kindness. So:

• Unfortunately, all fuses mentioned above check OK. I was REALLY hoping it would be one of the fuses!
• Indeed, as a USA car, the clutch pedal must be depressed to start the car. So car ebrake on, tranny in neutral, feet off pedals, turn key and no start. Same setup with clutch pedal in and it starts immediately.
• I have the Bentley manual that came with assorted items in the trunk of the car. I also have a Peake R5 FCX3 scan/reset tool and additionally, a BMW diagnostic port to OBDII cable. In looking for the "BTS Implausible" I set the tool to Fc and it tossed the following codes in order:
  • DEC: 15, 26, 92, F6, F5, 27, 83, 84
  • HEX: 21, 38, 146, 246, 245, 39 , 131, 132
  • I attached a picture of the very sophisticated paper towel listing of codes
• Being a relative newbie I began searching for the meaning of the codes (and their hexadecimal equivalents) and found them at http://www.endtuning.com/bmwcodes.html#MS41. The codes were under DME MS41, MS42, MS43 (mine is MS42.1). HEX 38 and 39 seem interesting given they relate to the clutch and brake switch. The success of the USA clutch switch test seems to negate the clutch switch error but the brake light switch error could be related to my issue? My brakelights work perfectly by the way.

So I am going to pull the brake pedal switch to see what I can see. When it comes to car electrical stuff, I am usually relegated to continuity, 12v and 5v stuff but I have a friend who is an electrical engineer that will help me with testing the switch

Meanwhile:

• I am going to reset the codes with the scan tool
• I am going to attach the BMW diagnostic port to OBDII cord to the car and to my BlueTooth MX+ adapter to see if I can find anything in those codes. It runs ObdLink software and has been tremendously helpful since Day 1 for all my cars!!
• BTW, the Check Engine Light (MIL) has never come on except when key on before start.

 

[NZ00Z3]

Hi

You are doing well with the scanner information.

Both the clutch switch and brake switch errors will cause the cruise control to stop working. Clear the codes and go for a drive and see what comes back. Change the brake/clutch switch depending on what codes return.

I'm picking that its the brake switch causing your problem. To remove the brake switch is a little tricky. There will be a coloured ring/collar (red maybe white??) that the plunger slides through. You need to pop this ring out towards the end of the plunger before the switch will unclip from the mounting bracket.

Keep up the good work, you'll soon have cruise control working.

Regards

Murray

 

[gookah]

do you have LED bulbs in your brake lights? they stop Cruise Control from working
ask me how I know...

they also put a brake switch error on, the same as on your readout

check them, and If you do, swap them back to normal bulbs,

see my recent thread here:
https://zroadster.org/threads/cruise-control-not-working-and-problem-found.30671/#post-496747

 

[staggerwing17]

do you have LED bulbs in your brake lights? they stop Cruise Control from working
ask me how I know...

they also put a brake switch error on, the same as on your readout

If you do swap them to normal bulbs,

Hello Pete!
Thanks for the idea! I am leaving the bulbs as they are - normal incandescent auto bulbs. I love LEDs and I use them whenever possible but I tried LEDs on my 95 325iC several years ago and could not get the resistance right to keep the car happy and error free. So, my Zed will stay original in this regard. Thanks again for the input!

 

[gookah]

has a previous owner fitted some though?

 

[staggerwing17]

Hi

You are doing well with the scanner information.

Both the clutch switch and brake switch errors will cause the cruise control to stop working. Clear the codes and go for a drive and see what comes back. Change the brake/clutch switch depending on what codes return.

I'm picking that its the brake switch causing your problem. To remove the brake switch is a little tricky. There will be a coloured ring/collar (red maybe white??) that the plunger slides through. You need to pop this ring out towards the end of the plunger before the switch will unclip from the mounting bracket.

Keep up the good work, you'll soon have cruise control working.

Regards

Murray

Murray thank you! Yeah as soon as it cools down a bit (111 degrees F here in Gilroy, CA at the moment), I will reset and see what is going on with the switches. This is tedious but educational so I will keep poking at it til it works!!

 

[staggerwing17]

has a previous owner fitted some though?

Now there is a thoughtful question! He did manage to get LEDs in the license plate lights but given the way the taillights, brake lights, turn signals, etc. come on, I am certain they are not LEDs. BUT, time to learn how to change bulbs in the taillight housing so it is worth checking now! Thanks for the follow up!!

 

[staggerwing17]

Update:

• I reset the codes with the Peake scan/reset tool. I took a 10 mile drive and upon return, a scan showed no Fc errors.
• I got the ObdLink MX+ BT adapter working with the OBDII to BMW diagnostic port cord. A scan of codes showed no codes present.
• I unplugged the brake switch cable and tested continuity across two terminals of the switch. Then across the remaining 2 terminals.
  • Result is that the switch seems to be functioning properly - a VERY, VERY slight touch on the pedal (by hand) causes continuity beep and further depression of pedal causes a beep in the second pair of terminals.
  • I am assuming the first beeping at light touch would cause cruise control to deactivate while the second would activate brake lights. I have ordered a new switch as a matter of course - if I am going to take apart the lower driver's side dash, I might as well replace the switch.
  • The extreme lightness of the touch on the pedal that causes the first beep might be a concern as it might never let cruise control activate?
  • Would adjusting the switch change this behavior?
• At any rate, awaiting new switch arrival and also the time to remove the existing switch which, with a clutch pedal in the way, looks a bit challenging.

 

[staggerwing17]

Further Update:
Perhaps ill advised, I disconnected the brake switch plug altogether. I knew brake lights would not work. I hoped that the plug being disconnected would be seen as an open switch condition that might let the cruise control function. After a 5 mile drive, no cruise control. While I am not sure if the removed plug should have eliminated the brake switch as an issue, the switch does work - it is just extremely sensitive and requires the very lightest of pressure to close the switch. Beginning to wonder if the FCR Interface Module is defective. Replacement switch hopefully arrives this week.

 

[staggerwing17]

And More Update:
Using a voltmeter I tested continuity across the top 2 terminals of the brake switch and then the bottom 2 terminals of the brake switch. Both showed an unconnected status with brake pedal in rest position. Depressing the brake pedal resulted in the 2 sets of terminals showing as connected. Based on the electrical diagram, this appears to be normal.

In case the cruise control was just looking for a closed circuit with one or the other sets of 2 terminals each (seems backwards to me), I unplugged the switch cable and put a jumper first across the top 2 terminals. Drove the car, no cruise control. Switched the jumper to the second set of terminals, drove the car, and still no cruise control. There is a new brake switch on the way. I am not looking forward to removing the current brake switch from the bracket. If the car was an automatic, it would be simple since the bracket that holds the switch is totally accessible and easily removed. But with a clutch pedal in the way, much more of an ordeal.

Questions:

1. Is there a way to confirm the FCR Interface Module I purchased used is functional? Is there a procedure for bench testing the module?
2. Does an option to enable cruise control in the ECU need to be turned on?
3. Any other ideas?

Thanks to anyone who has read this far!!!

 

[NZ00Z3]

Hi

Just back from testing my cruise control setup with my scanner. You have had me thinking hard on this one.

1) Yes you can bench test the main functionality of the FGR switches e.g set, accelerate, decelerate, switch off, switch on etc. You can see the status of the digital signals change as you operate the cruise control stalk. This proves that the FGR is talking to the DME (ECU). Unfortunately you can't enable the FGR with the scanner as the car has to be moving 30km\h or 20 mph etc. You can also see/test the functionality of the clutch switch, brakes switch and brake test switch.

2) This is a possibility. I have installed the cruise control onto Z3's from the UK and Japan markets without having to turn on the cruise control function. Haven't had the pleasure of working on a USA Z3 yet, so can't be sure. If the FGR bench tests OK, then I would suggest that no coding is needed.

3)
- Install the new brake switch
- Consider INPA or a good BMW specific scanner to bench test the FGR

We're getting very technical now, hope this helps.

Regards

Murray

 

[NZ00Z3]

Been doing some research on cruise control and came across the following:

Switch-on conditions:

- ”Accelerate” button in neutral position before switching on cruise control.
- The minimum speed of 30 km/h must be exceeded.
- The brake pedal must be in rest position.
- The clutch pedal must be in rest position on vehicles with manual gearboxes.
- Drive stage ”2” to ”D” must be engaged on vehicles with automatic gearboxes.
- No switch-off condition must be active.

Faults detected in the cruise-control system are stored in the fault code memory of the engine control unit. These fault code memory entries prevent any activation of the cruise-control system.

Cutout conditions:

- Deactivation via main switch
- Operating brake pedal
- Operating clutch pedal (manual gearbox)
- Engaging drive stages ”P” or ”N” (automatic)
- Off: switches off the cruise-control system.

 

[staggerwing17]

Hi

Just back from testing my cruise control setup with my scanner. You have had me thinking hard on this one.

1) Yes you can bench test the main functionality of the FGR switches e.g set, accelerate, decelerate, switch off, switch on etc. You can see the status of the digital signals change as you operate the cruise control stalk. This proves that the FGR is talking to the DME (ECU). Unfortunately you can't enable the FGR with the scanner as the car has to be moving 30km\h or 20 mph etc. You can also see/test the functionality of the clutch switch, brakes switch and brake test switch.

My test setup is a program called INPA running on a old surface pro. INPA is free and can be downloaded from the link below. INPA is BMW's development platform and is very powerful in doing diagnostics. It needs an old computer/laptop/surface pro with windows (between XP and windows 10) and a USB2 port. You need to purchase some leads to connect to the round diagnostics port under the hood. Details in the link.

https://www.bimmerforums.com/forum/...tions-Experiences-Discussions-Experimentation

If loading software and setting up a computer is not your thing, then research the Foxwell NT520 scanner with BMW software. I have not had the opportunity to play with this scanner, but it's spec reads very well and may go into enough detail to bench test the FGR.

2) This is a possibility. I have installed the cruise control onto Z3's from the UK and Japan markets without having to turn on the cruise control function. Haven't had the pleasure of working on a USA Z3 yet, so can't be sure. If the FGR bench tests OK, then I would suggest that no coding is needed.

3)
- Install the new brake switch
- Consider INPA or a good BMW specific scanner to bench test the FGR

We're getting very technical now, hope this helps.

Regards

Murray

Hello Murray!
I can easily see the value in the INPA software and I have a Win10 PC I could use. I may move ahead with that but I have never used a program like that before. My buddy who is a Jaguar guy has software for his 3 Jags (and my 2005 XJ8L) that appears similar to the INPA software so I will get as far as I can and then ply my friend with steak and wine!!

I will admit to being a bit frustrated - the FCR unit was used on eBay. I contacted the seller and he did not know how to test the FCR unit nor did he test the unit form his donor car (also a 1999 BMW Z3 M52TU mfr one month later than mine in 4/99) so really no sure way to know if this one is functional. I would not imagine it to be a high failure rate item though.

I hope I am not causing you to spend too much time on this topic! I am extremely grateful and I hope that what you learn will add to your obviously considerable bag of deep knowledge. I will look into INPA ASAP!

 

[staggerwing17]

Been doing some research on cruise control and came across the following:me

Switch-on conditions:

- ”Accelerate” button in neutral position before switching on cruise control.
- The minimum speed of 30 km/h must be exceeded.
- The brake pedal must be in rest position.
- The clutch pedal must be in rest position on vehicles with manual gearboxes.
- Drive stage ”2” to ”D” must be engaged on vehicles with automatic gearboxes.
- No switch-off condition must be active.

Faults detected in the cruise-control system are stored in the fault code memory of the engine control unit. These fault code memory entries prevent any activation of the cruise-control system.

Cutout conditions:

- Deactivation via main switch
- Operating brake pedal
- Operating clutch pedal (manual gearbox)
- Engaging drive stages ”P” or ”N” (automatic)
- Off: switches off the cruise-control system.

Wow Murray these 2 lists are very useful!! Thank you.
So my test drive to see if CC is working goes like this: Drive to main road where I can maintain at least 55mph. 5th gear, no brake, no clutch and no gas. Move CC lever forward with foot still off gas. Hope and pray. If not successful then same procedure but keep foot on gas to maintain speed. Hope and pray. If neither effort works, drive around anyway!! This car is just absolutely wonderful!

A couple of odd questions:

1. Is brake pedal on a condition for activating top up/down? I know ebrake and window position must be correct. Curious as this might validate proper function of brake light switch.
2. Is the "main switch" mentioned above the control stalk lever? I assume the CC is always ready and pushing the lever forward activates it (no other switches).

Thanks again and take care Murray!

 

[gookah]

If you have INPA it is easy to see the brake switch status.

Select the body module,
Then select your asc module. Think it is the asc/ dsc e46 one, (I can check later)

Once you are in that screen, press the "Read Status" (F5 I think.)

Scroll down a bit and you will see a circle against "brake lights switch".



This should turn black only when the pedal is pressed.

Mine was constantly black with the LED bulbs in, hence the cc thought I had my foot on the brake, and would not kick in.

Old style bulbs refitted, the circle went clear, and changed to black only when the pedal was pressed.

Incidentally
my roof still worked with LED's in, though a fault was present.


There is another screen which shows brake light test switch and clutch switch, but I cant remember where I saw them. Will check later.
Even though you have an auto, if you have a blacked out Clutch Switch circle that would stop it

 

[staggerwing17]

Wow! I will be looking into INPA later today for sure. I have the 5sp manual in my car so will be good to see the clutch switch status confirmation. Thanks so much for the post!!

 

[NZ00Z3]

1) Yes the foot brake "on" is a condition for activating the motorised soft top. It uses the main brake lights side of the brake switch, so can't be used to validate the brake switch.

2) The "main switch" is not obvious to me either. As this is a set of generic information for the E36 platform, it may refer to the ignition switch or to a "on" switch which activates the CC in another model. You are correct in that for the Z3, the CC is always active.

 

[staggerwing17]

Murray thank you for the answers!