2016 Volvo XC90 T6 (B4204T27) 2.0L NO CRANK NO START

Hey Everyone,

My name is Shay from Tel Aviv. I'm a long time member and an enthusiastic DIYer.
My day job is a film producer but this crazy hobby of mine and thanks to the great Scanner Danner education:) got me to a point that local garages consult with me to solve some of their major problems. :lol:

So here's a tough one I need some help with:

2016 Volvo XC90 T6 2.0L (B4204T27) with a No Crank No Start situation after a brake job at a local garage.

CEM doesn't activate Ignition Relay K15 so no power to ECM, TCM etc. When shorting the Relay power comes on, but still a No Start.

Car came driving OK situation happened right after finishing the brake pads replacement.

Secondary battery was very low (2.5V) but no difference after recharge and/or using a booster battery.

Also checked the S terminal on the BCSM and there is no power to ECM from pin #1 (tried direct power to this wire but no change).

I'm struggling with finding the original wiring diagrams (downloaded the Mitchel DIY and found some mistakes which makes it even more challenging)

If anybody has any experience with this type of car and can guide me to what kind of inputs triggering the starting sequence and the order in which it happens it would be very helpful.

I see no Key/Immobiliser error
Have NO communication using my Autel MS906BT with any module (of course - no power) also when shorting the ignition relay! but strangely when doing so I do have communication with OBD2 generic mode....but no relevant errors...

THANKS FOR HELPING!
Shay

Did the garage do the brake job correctly?

Was the vehicle put into service mode with a scan tool...Brake work performed... Vehicle taken out of service mode?

The vehicle may not start while in service mode.

If they did not follow the procedure with the service mode, it might be possible the vehicle is locked out. I've never seen this yet though.

K15 doesn't supply power to the ECM/TCM. I'm looking at Alldata and it matches your photos.

You need to address the communication issues first.

When you say no power for the Autel, is there power at pin 16 of the DLC?

If there isn't power at pin 16 a jumper power from the BATT to that wire with a backprobe, a piercing tool or use a break-out box.

No Comm with the scan tool would be my first priority.

Thank you so much Paul!I will definitely check all the wise notes you’ve mentioned. Starting with communication. That’s my next step.I do have power to pin 16 but no com except for the CEM and other convenience module but not the ecm.Not sure about K15 relay but I experimented with it and the only way to get power to the ecm was to jump this relay. By the way can you look at the starter diagram - is there not a mistake with the wires from the relay to the starter?I also don’t understand the inside configuration of the brake switch.. is it a mistake there?Thanks again I really appreciate this!I will be updating:)Shay

Quick Update:

1. Checked the resistance between pin 6&14 - its 60 ohm - OK

2. Measured voltage on 6&14 using a break out box and scope. Also connected directly to several can bus wires (TCM, ECM, STEERING module) - and got normal communication patterns around 2.5V (see attached pic)

3. I can communicate with the ECM only in OBD generic mode - I have Live data, got 5V to sensors (ECT, AIR TEMP, etc.) + no error codes.

4. Have communication with CEM (body control module) and live data that confirm inputs from start switch and from brake switch are OK.
But one PID caught my eye - its the Alcolock input that reads - START NOT ALLOWED - but there is no Alcosystem in this car..... (See PIC attached). anyway I guess its not the reason for not having communication with all the important modules (ECM, TCM, ABS, STEERING, SRS, EPB etc...)

What can cause a NO COM to all these modules if there is other communication on the CAN BUS and no short or wiring issue?
Is unplugging modules one by one should be my next step?
What else am I missing???

THANKS!
SHAY

Try a different scanner.

Sounds like you got everything you need. Maybe there is an issue with Autel enhanced side for Volvo.

***EDIT***

I looked at the non OE information bus diagrams, if the Autel is only communicating on Generic OBD it is getting ECM info on a different Bus Protocol because it appears that the VCM (Vehicle Connectivity Module) is the Central Bus Gateway. Autel will tell what bus it is communicating on, It's not 6,14 I would think considering your issues.

This is further consideration the Autel Scanner has some sort of issue.

Thank you Paul.

So if I understand the situation correctly it is as follows:

I have 2 problems -

1. Missing an input that prevents the car from starting.

2. A scanner no com problem that prevents me from finding out what input is missing.

The thing is - the garage owner claims he could communicate with the Parking brake module through Autel Hot Functions in order to extract the calipers before doing the brake job. It was only later on that the communication and the no start occurred…

I attached the Alcolock PID that state START NOT ALLOWED. I’m not sure if it’s related but according to the owner there is no Alcolock on this car…

Thanks so much for helping!!!

I will further investigate and update
Shay

Well there is only so many things that can happen

1. Was it only an Autel Scantool that was used?

There are some caveats with using Launch, Thinktool, Topdon, and Autel (ALL CHEAP CHINESE TOOLING). They use reverse engineered code they stole from OE's to code thier tools. They don't get a lot of stuff correct, whether it be service functions, or Viewing PID Parameters. They have gotten better over the recent years though, mostly because of users telling them what the bugs are.

But I personally have had many occurances where my Thinktool, Launch, Autel would not perform a task, only the factory tool would.

Knowing this about these tools, always keeps me weary when strange things start to occur. And reaching for the OE tool more often than not corrects the problem.

Here is the shining example your Autel tool states an Alcohol Lock and its active with a no start condition.

Here is the problem, the Chinese tools will list that PID whether the vehicle has it or not, they will list EVERY Pid possible for the whole car line whether it had it or not. It's up to you to determine if the vehicle really does have that PID.

So in your case is that Autels Default way to display the PID? You can email them through the tool itself to ask. I don't beleive this PID is your issue, but without an OE tool it can't be proved.

At this point I would be reaching for a factory scan tool, to rule out any tooling issue.

I still think this vehicle is Stuck in Service mode and you could possibly have a module with a bit locked, and needs replacing/reprogramming.

Check the basics first, does everything power up that should with the key ON. Do all the modules that involve cranking have good power and grounds?

Also disconnect the battery and cross the cables to completely drain all the capacitors in the vehicles modules. This might help.

The other thing that bothers me is you stated you had a clean signal at PIN 6,14 with key-on. There is no reason for the Autel tool not to communicate. You should monitor the CAN signal for the moment you plug in the Autel VCI!!! It could be corrupting the signal.

You would think would set some codes. This is an interesting one for sure.

Verify what is good to find the bad. But try a different scan tool if you have access to one.

Keep us posted!

Quick Update:
After a short break due to my REAL job, and with no luck finding another scan tool, I have returned to working on the car and made an exciting discovery today. While examining the ECM, I noticed that one of the CAN bus lines was producing a faulty signal (see attached picture). Interestingly, based on the diagram, this line is supposed to be connected to the 6 and 14 DLC, which should provide a good signal. I can't help but wonder if there are additional errors in the diagram, as I've already identified a few. Nevertheless, tomorrow the garage will focus on the ABS module (referred to as VDMS Vehicle Dynamics Domain Master by Volvo) since, according to the diagram, it is the only component wired to this communication line. I'm eager to see if there is any communication established.
Also found a Service bulletin regarding the VDMS module that is related this problem!

Great work Shay, fix that CAN issue, and maybe the software update, you'll be good to go!!!!

The CAN waveforms should mirror each other, like the first test earlier in this thread.

Hey Guys
Just a quick update on the Volvo:
It turned out the ABS (VDDM) module is faulty as I figured out from the abnormal CAN waveforms. They're trying to fix it.
To be continued:)


AND FINALLY - THE CARE IS FIXED!!!!!
The ABS module was identified as the source of the issue. After replacing and reprogramming it, communication was restored, and the immobilizer code was recognized, allowing the start sequence to be regained.

Thank you so much for all the help!!!!