S40 (New) Brakes : BCM code 0101

[Bloders2]

Hello.
First post. A long post, but I have searched the forum but cannot find the answer unfortunately. So am putting as much detail here as I can.
I have a 2006 S40 1.6 diesel.

When driving, sometimes straight away, sometimes after a few miles, the traction control light comes on, along with the message about "anti skid requires servicing"
Also, the car drops into limp mode, with no Engine light on.
The strange thing (to me) is that sometimes, it will come out of limp mode on its own and carry on fine.
Stopping and starting the car resets limp mode until next time.

Codes have been read and cleared. Driven the car and read again.
Using a snapon scanner, I have been given three codes.
1) Engine management module
6720 EGR regulation flow too low. (Sometimes the engine light comes on and I get EGR codes with a generic scanner. This is not very often though)
2) Electronic Control Module
3A00 - ECM software faulty signal
3) Brake Control Module
0101 - Connection between control modules.

This is obviously an intermitten problem, as sometimes it will drive ten miles without the traction control light coming on.
I believe it comes back out of limp mode because possibly, the ECU has re - established its connection

I have in my mind it is one of the following
1) wiring between main ecu and abs ecu?
2) ABS ecu is kaput - if so, can they be repaired for this fault?

3) Is there a way of temporarily disabling the traction control whilst I get it investigated
Can anybody please shed any light on this.
I am near Wrexham. Does anybody know any Volvo experts near me who could help?

Thanks in advance

[s40futureproof]

I have exactly the same problem with same error codes that pops up randomly every other month of driving.

But I do have a constant code that reappears immediately after shutting the engine off after clearing it off the ecu: EGR offset fault.

I used to have the limp mode every othe week and I needed to clean the EGR from the build up of soot and reset. This has helped and it takes longer before fault comes back. I need a multimeter to diagnose for sure but until I get one I temporarily sort it out by switching the engine off for three minutes clears the fault from the dash and restores full power.

I came to same conclusion as you have. Either a wiring/ terminal connector fault/corrosion/spread pins or a bad computer. Also known as a bad 5v reference on the ecu the that receives feedback from the EGR valve position back to the computer. The EGR themselves are normally solid but have been known to go bad sometimes although this is rare. It is GM ecu that go bad a lot. A multimeter will help you diagnose what is actually at fault and Volvo has a bulletin on how to troubleshoot this issue.

[Bloders2]

thanks.
I dont believe the EGR fault is the cause of limp mode, as i often get limp mode WITHOUT the engine light coming on.
Do you think they are connected?

Can you point me to the bulletin on troubleshotting this please

[The Thong]

Just to let you know, the BCM's on S40 and V50 are a fail point. My BCM failed last year and it cost me £650 inc fitting at the dealership.

TT

[Bloders2]

Originally Posted by The Thong

Just to let you know, the BCM's on S40 and V50 are a fail point. My BCM failed last year and it cost me £650 inc fitting at the dealership.

TT

I understand that, but most BCM failures are related to actautor valves i think? which is why im concerned a 0101 error may not be repairable. Ifi I know its the BCM, ill be sort of happy, as I can get that repaired at either BBA Reman, or ECU testing, and the car will be spot on again. iykwim

[Bloders2]

bit of an update for those that are interested or can help.
I have an icarsoft scanner, which gives quite good level of access.
when interogated, the BCM module as above is 0101, which is an issue with communication with the ECM module.
I cannot get access to the ECM module.
I am thinking it is probably a wiring fault to the ECM, as neither my code reader, nor the BCM can communicate with it.

any thoughts on this?
I think the 3A00 is down tot he car being remapped, and thus is a red herring.

BTW, the anti skid issue was present before the remap, so i dont believe its the issue

[paddyred]

Hi Bloders,

I was looking at the system map and its an odd issue that you have. The BCM uses the same wiring as the CEM to communicate with the ECM on a CANBUS network.

See page 28: http://www.volvowiringdiagrams.com/v...%20Diagram.pdf

It wouldn't hurt to get access to the ECM which is behind the nearside front wheel arch liner. Disconnect the battery and pull the connector off the unit and have a look at the terminals. The unit itself is pretty exposed to water in reality. Also check the earth connectors on the left McPherson strut tower as that is where the ground terminal is for the ECM.

If the terminals are fine then your next job gets a bit more involved. Next you need to look for the Gray red and Blue red wires coming from the BCM, ECM and CEM they are the CANBUS communication wires between the units. You want to check all of the connectors and pins on all those wires and on all of those units. Hopefully the wiring diagram helps.

I also think that the issue with the communication on your OBD device with the ECM is more likely an issue with the limitation of your handheld unit. If you couldn't communicate with it then your cars CEM (Where the OBD port is actually connected to) wouldn't be able to connect with it either and the car wouldn't start.

*edit* I've just realized you used a snap on scanner. The Electronic Control Module it refers to as an ECM is actually the CEM (Central Electronic Module) on the Volvo's. ECM (Engine Control Module) on the Volvo's is the ECU. Have you pulled the CEM out from under the glovebox, cleaned the connectors and reseated all the plugs yet?

[Bloders2]

Hello.
thanks for your reply - just seen it.
I also have a icarsoft scanner - pretty reasonable for the money for reading codes.
It has found the same codes as the snap on unit - though i do not know if thre snap on successfully connected to the ECM or not?
I DO have access to the CEM but not the ECM!
I also have access to the BCM, diesel engine and lots of other modules.
Today, in the hope if finding a broken or stressed wire, I have removed teh ecm, removed and cleaned all the fuses, and reconnected up, making several movements of the connectors to try and clean the pins up.
I have one the same for the ecu (ECM??) behing the NS wheel arch, and also the BCM. Ihave cheecked (visually) the cabe ends, and also the route between fusebox and BCM and ECM.
I will check the earths as you suggest and take a look at the wiring diagram, but im getting stumped on this one and not sure what to do
Maybe o have a duff module, though I dont know why the icarsoft scanner wont connect to the ECM.

[paddyred]

Like I said the icarsoft scanner may not be able to connect with the ECM (ECU). If your getting live data about engine perimeters and readings and having access to engine fault codes then you must be able to "access" the ECM as this is quite literally the engine control unit so engine fault codes and live data will be processed by the ECM and then sent to the CEM along the CANBUS line and stored which is then accessed by your scanner. If you are able to access the diesel engine as you say then you MUST be able to access the ECM and there may be a software glitch on your icarsoft scanner so it doesn't recognize the ECM as connected properly. The only time you really need to access the ECM is to re-program injector calibration codes etc which is more in depth than the icarsoft is able to achieve as far as I am aware.
Have you removed the CEM plugs with your battery off etc? It may be also worth taking the cover off your CEM and checking for corrosion on the board just to make sure. I know I keep saying about the CEM but it seems to be a weak point on these vehicles.

You said you have done all the work today but have you cleared the codes, gone for a drive and they have re-appeared?

[Bloders2]

Originally Posted by paddyred

Like I said the icarsoft scanner may not be able to connect with the ECM (ECU). If your getting live data about engine perimeters and readings and having access to engine fault codes then you must be able to "access" the ECM as this is quite literally the engine control unit so engine fault codes and live data will be processed by the ECM and then sent to the CEM along the CANBUS line and stored which is then accessed by your scanner. If you are able to access the diesel engine as you say then you MUST be able to access the ECM and there may be a software glitch on your icarsoft scanner so it doesn't recognize the ECM as connected properly. The only time you really need to access the ECM is to re-program injector calibration codes etc which is more in depth than the icarsoft is able to achieve as far as I am aware.
Have you removed the CEM plugs with your battery off etc? It may be also worth taking the cover off your CEM and checking for corrosion on the board just to make sure. I know I keep saying about the CEM but it seems to be a weak point on these vehicles.

You said you have done all the work today but have you cleared the codes, gone for a drive and they have re-appeared?

yes codes aqlways come back after clearing.
I dont disagree about CEM, will look at it later this week when im able to get to it. Do you think its worth trying a different one - one on web same part number for £40?