On cold winter day Bravo 1.4 tjet 110kw (-29c at night) lost some brake fluid and clutch pedal was on the floor at the morning. Concentric slave cylinder might have leaked those out. Thats mechanical fix

But... I heated up motor with electricity later that day and tried to start the car (as i did my other car - Stilo). Stilo was running good and started easily but Bravo started only few seconds and off... I tried again and same happened and after that not at all. Maybe something was smelling outside. Also immobiliser activated in some point.

Multiecuscan showed u1601 on Ecu, dashboard is saying "hillholder, esp, asr and one parking sensor fault". Body computer seems to ignore now Ecu as an canbus module and cant find it. Also bodycomputer has codes for missing ecu, sometimes abs, steering, yaw node and minicrypt.

Some fix & tests made:
- recharged battery, check grounds under bonnet and c038 next to airbag module.
- pushed inertia switch and disconnected it totally, but not effect
- proxi alingment with Multiecuscan, but doesnt find ecu and abs
- tried key update with Multiecuscan, but didn went through with electricCode.
- ordered green cable for abs-log in with multiecuscan
- checked fuses and relays beside battery
- cleaned connectors and checked wirings visually
- then canbus network testing: body computer has 44/45 wiring for highspeed canbus
and while doing resistance test it shows 120ohm when ecu is connected and while it is disconnected ohms change. But if abs-module is disconnected and ecu is connected - resistance from bodycomputer 44/45 is not 120ohm...multimeter showed open circuit resistance.
- metering in abs-connector (disconnected abs-module), ignition on, canbus lines to ground - other side is 3,2v/1,8v and towards ecu 0,2v and 0,3v ?
- If abs-module is disconnected, body computer finds powersteering module and yaw-module back with proxi alingment.
- I checked also wiring from abs-module to ecu a-connector 88/89 canbus pins.
- Supply power and grounds for ecu a-connector seems to work also and main relay t9 metered in fuse f17.
- printed all elearn wiring diagram for the start

After all I have thought that is it just because of hydraulic pressure plausibility in abs-control-module and next I need to bleed that brake-line. Seems that it somehow hold fluid now... Could that abs-unit stops the whole communication in that canbus-network ? But for some reason disconneting abs-unit wont bring ecu back... Or could that ecu burn out just like that?

I think the abs-unit could do something to not let you drive, as the brakes are an essentialy system and it has to be working, but I dont't think that it could not let you "see" the ecu by Multiecuscan. Bleed the brake-line anyway and see if that helps.
Maybe your ecu is not burned out (it shouldn't be) but maybe you have a connection problem, like in this video:
https://youtu.be/VaLWkyfFHj8
The cold does contribute in accentuating a connection problem.

thanks, I will bleed that clutch and will see then. Multiecuscan can connect ecu with it's diagnostic line but body computer wont recognize ecu via c-can network.

I hope that multiecuscan can connect to that abs-unit (ordered green cable for obd) and show some more error codes in that.

I'm just learning to measure c-canbus lines and modules and it's quite challenging Can someone advice me easy spot where to measure resistance for can-H and can-L - where it should be 60ohms in Bravo. Obd2 pins 6&14 wont give measurement - I quess because of gateway between low&high speed canbus networks (same in Stilo). If I disconnect abs-module and measure those four canbus-pins in that coupling, I didnt get 60ohms while every other module is connected?

Clutch is workin better after bleeding, but car wont start.

Some codes and measurements (while OBD2-elm327 connected):
Error codes in ecu: u1601
Body: u1701 (ecu), u1706(brake), u1702(steering), u1715(side accelerator) and u1600(minicrypt)
Dashboard: immoblisator sign

When I unplug OBD2-cable from USB-laptop
Dashboard: no immobilisator sign ? (elm327 has some effect for that...)
Asr, Hill holder, esp/asb warnings

C-can tests:
Unplugged ecu a-coupling and battery, 120ohm in 88/89 pins: correct
Unplugged also body-coupling: no ohms in ecu 88/89: correct
Connected ecu a-coupling, unplugged body and ohms in body coupling 44/45: 120ohms correct
If ABS-unit is unplugged and ecu connected, no ohms in body 44/45 pins. Thats maybe weird ?
Abs-unplugged and others connected, 120ohms in ABS pins 15/26 and 120ohms 14/25. Correct.
If ABS-module is unplugged and battery plugged, body finds Steering, Yaw-sensor but not ECU through c-canbus network. .

What I have read, usually high speed canbus network is like a tree - 120ohms resistor in each end (ecu and body) and ABS-module is like branch. Wiring diagram for can lines are drawn through ABS-module but the picture for lines shows that it's like a branch.

Elearn: "Via the CAN line, ABS control unit M50 is connected - from pins 14 and 25 - to the engine management control unit M10 and, from pins 15 and 26, to the Body Computer M1 and the instrument panel E50, to manage the ABS warning light and, if the problems concern the EBD function, the low brake fluid level/handbrake applied warning light." and "The ABS is detected as a component of the C-CAN network by the body computer at the first key ON."

I have not found ABS-module internal resistance yet. https://www.kmpdrivetrain.com/paddleshift/practical-tips-can-bus/ and this says that high speed canbus has resistance only at the end-line-modules. In pins 15/26 and 14/25 resistance is like open circuit (inside ABS-module)? K-line connection for ABS-module maybe tells more about ABS-unit, but if someone has ideas for more measurements - please let me know

I can connect to ECU via K-line (diagnostics) and ECU seems to have 120 c-can resistor inside, so it seems to be ok. Maybe that ABS-unit is offline...and ECU-is missing as a canbus node because of that?

Skywriter said:

I can connect to ECU via K-line (diagnostics) and ECU seems to have 120 c-can resistor inside, so it seems to be ok. Maybe that ABS-unit is offline...and ECU-is missing as a canbus node because of that?

Click to expand...

It may be. But remember what you know for sure: when the problem first appeared you had no clutch due to lack of clutch fluid. You say now it is ok. Maybe you have a punctured brake-line or something like that and there is where you lost the fluid through. And maybe from that cause your brake system does not appear to be working, because it dosen't have the required pressure. And brake being an essential system, one that you cannot drive without it being in working condition, maybe it cuts the communication as you've mentioned. Try to find the place where the brake/clutch fluid got lost through.
Good luck mate!

Thats true... in this model slave cylinder is concentric - inside the gearbox. I didnt find yet where fluids exactly leaked out. Master cylinder (under clutch pedal) seems to work and its dry, pipes lookin good, so I was guessing it might be the seal in slave cylinder. BUT it's strange that now I can push the clutch and it returns back after bleeding the slave cylinder.

ABS-unit might also leak somehow but not sure. While pressing brakes, pedal is quite hard to push.

I tested ABS-module power supply pins and ignition on pin - battery voltages ok. Ground contacts in ABS-coupling also ok.

ECU and now also Body computer shows error u1601, so both are looking towards ABS-module. Testing continues

After many measurements and walking through diagrams I started again at the basics and now found one intresting ground point what might affect a lot in this case.

Can someone confirm that c038 ground point in Bravo tjet 110kw should continue to the junction unit under dashboard to coupling H 10/19 pins. C038 is found nearby airbag-module.

I measured those wires and other one gives resistance 4kohm. Other seems not to have continuity.

How would be easiest to make new ground contact for that place?

You are rapidly becoming the expert on your problem.
Please carry on updating us.

jackwhoo said:

You are rapidly becoming the expert on your problem.
Please carry on updating us.

Click to expand...

seems that c038 ground to body computer might plug in behind that unit, so it's difficult to check...

Ealier i thought it's coupling in front of it...

My "best bet" is now that ABS-module is somehow broken or silent otherwise. When it's disconnected, steering and yaw-modules are recognized by bcm. When ABS-module is plugged back, steering and yaw-modules will be removed from bcm. ECU wont show up although lines goes through ABS-module. Thats weird because 120ohm resistor is online at that time (measured bcm connector H 44/45).

Now I'm waiting for new cable for multiecuscan to see inside ABS-unit if there is some "hard-errors". ECU and BCM are showing c-can network error and ECU says also that it cant connect to BCM. I'm looking for replacement ABS-unit if that would fix that can-network.

Root cause for that clutch-fluid-leak is still missing - after bleeding clutch, it seems to work now. Difficult to imagine that abs-module could somehow affect clutch and also can-network. Maybe these are separate cases or there's too much air inside abs-pump.

Step by step

As for your clutch, I had similar problem witch clutch pedal down and it was concentric slave cylinder. When I pulled pedal back it worked again but now and then it dropped again. The only solution was changing the cylinder.

Trubkin said:

As for your clutch, I had similar problem witch clutch pedal down and it was concentric slave cylinder. When I pulled pedal back it worked again but now and then it dropped again. The only solution was changing the cylinder.

Click to expand...

Yes, that's maybe same thing in my car.

About the abs. I contacted Bosch repair and they said that actual model number is in label and that was just next to the chassis. So i removed abs-module and it's now off the car.

In this video: https://m.youtube.com/watch?v=52rGiRCMJ4I guy is testing canbus wires. Those goes through abs-module and while he removes abs-connector, 120ohm show up in multimeter (connected to OBD2-14/6 pins). Still wondering which test would proof that canbus wires in my car are good or bad. In full working Stilo Obd2 14/6 does not show ohms and same thing in Bravo (and maybe thats because of gateway between lowspeed and highspeed canbus).

Here is c-can lines in Bravo:
https://drive.google.com/file/d/1_Lqy5hXf-NOENZU3-lz7rLMxYpZ4M8lv/view?usp=sharing

And here c-can lines in Stilo:
https://drive.google.com/file/d/1tOZWSsC6Zp-ElejBzivV-sIfuUGbQSxn/view?usp=sharing

Bravo lines goes through abs before Ecu and in Stilo wires goes first to ecu and then to the abs-module.

To quote Jack, "You are rapidly becoming the expert on your problem".
Try testing the wires, but if there are no ohms in full working cars, you should think of another way to discover where the problem is.

Yea, trying to think other ways. Weirdest is that ECU wont discuss via c-can with bcm through ABS-module. Pins inside abs-module has continuity for canbus-lines. Wiring is good from bcm to abs-connector. And also from abs-connector to ecu-connector A.

Some clue is in Multiecuscan ECu u1601 error code. It says, that battery voltage was 9,2v althought it's 12,6v on battery. I will receive used abs-module next week, so will see then if that get the motor running.

I was wondering about the error codes you get, if those aren't any help.
It's good you get another abs-module, I ithink you will be able to figure things out with it. It's good if you know for sure that that one is working. Do you get it just for testing purpose or for good?

Had a quick look through but have you tried replacing the main earth cable or anything least putting a jump lead form the battery negative to the engit block?


Just reading if the abs module is reporting 9vits could be a simple voltage issue

Have to test that too. I made measurements for grounds but i didnt replace any wires yet.

One idea that could sum this up: if ABS is somehow internal-shorted and affects to canbus voltages, ecu error code (u1601) says that canbus voltage is too low and c-can wont fully wake up. Ecu and Abs wont then show up in BCM. When ABS is disconnected, C-can works partly and Yaw ans Steering show up with better c-can voltages. Is that possible, not sure

Maybe in the future these modules are connected like USB-hardware in homecomputers

Spare part will be for this car, not just testing.

Some progress in this case

I got green adapter for Multiecuscan and logged in to my old ABS-unit. It was filled with error codes and i took photo of those if needed later. Cleared codes. Also steering had CAN error and ABS-unit informed me steering angle sensor error. That sensor seems to work while turning steering wheel.

I cleared also BCM errors and ECU errors and somehow after all these clearings - BCM found ECU and ABS nodes back, but not steering. I made proxi alingment again with these new nodes.

Engine promised to start, but not yet. Have to clean spark plugs and give it some electric-heating, maybe later...

Skywriter said:

Some progress in this case

I got green adapter for Multiecuscan and logged in to my old ABS-unit. It was filled with error codes and i took photo of those if needed later. Cleared codes. Also steering had CAN error and ABS-unit informed me steering angle sensor error. That sensor seems to work while turning steering wheel.

I cleared also BCM errors and ECU errors and somehow after all these clearings - BCM found ECU and ABS nodes back, but not steering. I made proxi alingment again with these new nodes.

Engine promised to start, but not yet. Have to clean spark plugs and give it some electric-heating, maybe later...

Click to expand...

Don't clean spark plugs using wire brush.
Just let them dry off.

Removed coils and spark plugs for drying. After almost two weeks, just got the motor running

At that time was frozen -29c weather, but I dont know what was actual technical reason for this all. I cleaned most of contacts and measured different wires. Maybe ABS-unit was the main reason for communication "bus off". Green adapter for Multiecuscan was good to buy. With that adapter it's possible to connect most of Bravos modules and no immobilser sign while it's plugged.

Good thing is that in these kind of situations you can learn a lot of your car

Will see is the motor still in good shape because it "tics" maybe little bit more than ealier. Oil change etc. is needed. Engine temperature sensor gave also weird temperatures.

Clutch is question mark that need more attention (seems that it hold a pressure) and brakes tomorrow.