2004 S60 "'Limp Home" mode Unknown Cause of High Speed CAN Bus Failure

[dreww]

Hello all,

I'm sort of stuck in terms of tracking down a problem where my 2004 S60 2.5T FWD vehicle has gone into "limp mode." It's happened twice and I haven't traced the root cause yet. Engine / Tranny has 210k miles.

I've had some significant issues lately. Specifics are as follows:

Date: 4/26/2017

Circumstance: Longer than normal traffic on morning commute ~45 mins in traffic (car hot)

All was fine then car went into "limp home" mode. All gauges (except gas) read 0, dashes "----" on digital display and "ABS" shown along with engine light (of course) and message "Transmission Service Required"

Stopped, turned off and re-started the car. Gauges came back and I took the car home without incident.

Engine codes on 4/26/2017: (pulled Codes with BSR PPC code scanner)

DDM002B Mirror motor MC. Signal too low

PDM 0024 Door mirror motor MX+. Signal too low

PDM 002B Mirror motor MC. Signal too low

CEM 1A59 Communication with the audio module (AUM). Signal missing

Reason: After market radio not on CAN bus.

CEM E000 Communication with control module. Faulty communication

CEM 1A61 Communication with the transmission control module (TCM). Signal missing

TCM E000 Control module communication

ECM 928C Control module, communication problems. Faulty signal

ECM 530B Communication, transmission control module (TCM). Signal missing

ECM E000 Communication control module. Defective signal

ECM 4050 Fuel level sensor. Faulty signal

==== CLEARED THE CODES === THE CODES BELOW CAME BACK AFTER RE-STARTING ENGINE ====

BCM 0100 Communication between control modules. Communication problems with the engine control module (ECM)

BCM E000 Control module communication. Faulty communication

ECM 4801 Three-way catalytic converter (TWC) efficiency, bank 1. Faulty signal

========= CLEARED THE CODES === NO CODES CAME BACK AFTER RE-STARTING ENGINE ====

I decided to drive the vehicle again. The vehicle drove OK for short hauls (<10miles) but had trouble again in traffic.

Date: 5/1/2017

Circumstance: Car went into "limp mode" at a stop light driving home from work. Drove in limp mode home. On the drive back there was a small buck/hard-shift/clunk in transmission the moment after going into limp mode and two times at speed (~45-55mph) during the drive home.

Engine codes on 5/1/2017:

CEM 1A59 Communication with the audio module (AUM). Signal missing

Reason: After market radio not on CAN bus.

CEM E000 Communication with control module. Faulty communication

CEM 1A61 Communication with the transmission control module (TCM). Signal missing

TCM E000 Control module communication

ECM 928C Control module, communication problems. Faulty signal

ECM 530B Communication, transmission control module (TCM). Signal missing

ECM 4050 Fuel level sensor. Faulty signal

ECM 4801 Three-way catalytic converter (TWC) efficiency, bank 1. Faulty signal

Since the car drives normally most times I believe it is mechanically sound but I could be wrong.

The comm. errors lead me to believe that the high speed CAN bus is being crashed. Which may point to the ECM, TCM, ETM, BCM or CEM. Which is crashing the bus? I've no idea. I did a heat soak on the CEM with a hair dryer for about 5 minutes as suggested by Xemodex techs which did not induce "limp home" mode. Perhaps this excludes the CEM as the culprit.

Any ideas on how to diagnose?

Some other info:

My mileage lately has suffered with about 22mpg where my typical is about 25mpg with no real change in gas or usage. I'm going to give the car a tune up (plugs/oil/filter/air filter) to see if this changes the behavior. I'm thinking a failing ECM might also cause similar symptoms but this is a guess.

I recently changed the tranny fluid by draining old fluid and and putting in 4L of JWS3309 (Volvo fluid). I also put in a b4 servo upgrade for the transmission at the same time. I've reset the tranny fluid counter via VIDA DICE and, when functioning (not in "limp home" mode), the tranny seems to shift ok.

I've removed the ECM and TCM with a purpose-built tool and Deoxit 5% the contacts/sockets. No problems for the few short driving sessions since this service.

Thanks for your consideration.

[AKellner]

Any problems sense?

[oragex]

Water ingress on the CEM was a widespread problem from 2004 on. I would look underneath at the module with a flash light for any dry or wet traces of water