ECM-912A CODE after new ETM install

[jjnuttall]

'99 V70 T5, 200k miles. Car is clean and pretty much corrosion free.

So I'm doing a XeMoDex ETM swap and running into difficulties. In addition to the new ETM I've installed a new Bosch MAF (German made) and Volvo ECM relay. The car won't run much longer than 10 minutes, then struggles to idle and dies. Hoping to get some good tips on how to best proceed.

First let me state I've read every post in "The ETM Room". I'm also working with XeMoDex tech support, they've been super great, very accommodating. After I performed all their required troubleshooting, they sent a DiCE unit to me and performed remote diagnostics finding this code. ECM-912A Communication with the Engine Control Module.

The feedback on the diagnostic session was that the ETM tested fine, the ECM-912A code persisted almost the entire time. There were a few instances where it cleared, so the thinking is that its not a permanent issue. An accelerator pedal code came up once then went away.

So their conclusion is that everything is pointing to the power supply to the ECM, but I posted here because this all started as an ETM issue, and there is communication between the modules.

So right now I've had the battery tested, and re-cleaned the terminals so that's good to go. I started checking all the ground connections I could find. I understand bad grounds can cause many electrical issues so I started there. I found the ground strap from the top of the head to the firewall was disconnected, so I cleaned that up and it's reconnected. I metered it for resistance, its good.

The ETM ground, on the block just above the starter motor, I had already cleaned up and re-fastened, I'd ohm'd it before thru the engine harness ETM connector.I also probed the ETM harness ground wire and tested resistance through the connection and it's good. There's a ground near the main fuse box bolted to the fender well that I've also cleaned and metered.

My goal is to systematically work through all the grounding points, then to work on the power side of the circuits. I'm having difficulty locating online wiring diagrams for the 1999 cars. The link from this MVS website is dead and volvowiringdiagrams.com doesn't have the needed diagrams.

So I'm asking for any tips, suggestions, pointers that would be helpful in running down this problem.

Thanks in advance

John
Raleigh, NC

[xHeart]

Unless member percopster says otherwise, ECM-912A is a CAN bus code indicating ECM and ETM have missed communicating with each other.

Unless there is a CEL, I'd continue with normal drive cycle -- work the battery to full charge.

[RickHaleParker]

ECM-912A is a report from the ETM to the ECM that it is having trouble hearing the ECM.
It is like when you got a bad phone connection, "I'm having trouble understanding you, bad connection"

Possible source
The power supply to the engine control module (ECM) ( Noise, interrupts, low voltage .. ect)
Loose connections or contact resistance in the terminals for the CAN signal cables.
Open-circuit in one or both CAN signal cables.
Short-circuit to ground in one or both of the CAN signal cables.
Short-circuit to voltage in one or both of the CAN signal cables.
Short-circuit between the two CAN signal cables.
Interference on the CAN signal cables.
Defective node in the Control area network (CAN).

At the ETM, the White and Green twisted pair are the CAN signal cables.
(Twisted around each other like telephone wire)