2004 xc70 All dashboard lights off- No Power

[Lauren04XC70]

To quote from records:

March 2013: CEM was found to have an internal open on the communication circuits causing no low side CaN communication. Replaced and programmed CEM.

April 2013: same problems reported.... Just diagnosed and replaced some bulbs

April 2013: all same problems, low side of the network had lost all communication. Found that when the REM is disconnected, that the network communication comes back online. Replaced and programmed the REM.

Jan 2014: all the same problems, the low speed CAN communication is going offline intermittentently, making this is a very difficult issue to resolve. The CCM and DDM were the first modules to go offline and also have several other faults. Replaced and programmed CCM and DDM due to several internal faults.

February 2014: replaced the Central Electrical Unit Capacitor and did ECM software upgrade.

Above was all previous owners. We purchase in April and have done a DIM module repair. Battery and alternator are both good.

Thank you for any help. Need to know if we can fully fix this car for lying term use or do we need to sell it. Thanks

[oragex]

ECM and CEM were replaced with new parts or were refurbished? Maybe the CEM wasn't properly fixed.

[Lauren04XC70]

Replaced new at dealership. According to notes, it seems dealership mechanics were frustrated/disinterested. We are trying to figure out if we want to try the CEM through Xemodex. Any and all comments are welcome and requested. Thank you!

[Lauren04XC70]

Bump. Please help! Thanks!

[oragex]

One other component that might interfere with the ECM & CEM communication is the center panel - the one with the climate controls. If I also remember well, the ABS electronic module (I think under the dash) is also known to fail at solderings and cause interference with the ECM and CEM. Further than that, all electric wiring needs to be inspected, including connectors for proper insertion.

I would also check under the dash drivers side there is no water leaking on the electronics from obstructed sunroof drain tube (also a common issue).

[jimmy57]

The CCM is a low speed module, it will not stop high speed comm.
BCM, ECM, TCM, DEM, and CEM are connected for high speed network ( also ETM if it is a 99-2001, and some 2002).
DEM wiring can short in DEM connector and kill high speed network.
WHen you see instrument issues do the turn signal indicator arrows still flash?
dead tach. speedo, gear position indicator and temp gauge are high speed supplied. Info failures if the gas gauge, message display, and turn indicator arrows still work.
You listed a lot of low speed network functions that still worked when you had failures so it would seem any low speed network module can be crossed off list.
The high speed network wires (green wire and white wire twisted together) run down driver's side inside wheel hump where you may be resting your foot. That pair runs along left door thresholds and then up under the rear bottom cushion under the carpet to a plastic storage bar that you can find if you lift the black under seat pad with the rear bottom cushion folded forward. The normal voltage on the wires is 2.15-2.30 V for one and 2.70-2.85 V for the other. IF the problem is present the voltage on the green and white wires under the rear seat would be telling to see if high speed network is shorted to ground or power.
Do you know if any CEM codes with DFxx pattern were ever found? DF code series is for shorts to power or ground or to each other for the network wires. CEM 1A51 through 1A68 are for individual modules being offline. Any 1Axx codes ever noted would be great to know.

[Lauren04XC70]

Here are the DTC's from previous work.

CCM-0007, E-001, DDM-0039, E-001, AUM-E001, PDM-E001, PSM, E-001, REM-E001, SRS-E001, SWM-E001.
Not sure what these refer to.

Turn signal indicators are not currently working. In the past they have operated the turn signal lights while the gauges are not functioning but there is no light in the cluster indicating that they are on. Also there is no turn signal sound inside the car while the cluster is dark.

I will get a volt meter and see if I can check those wires under the rear seats. Thanks for your help.