Hi guys,

This is a 2007 AM Vantage with a High CAN and Low CAN issue so I couldn´t start the car. The car had an small accident and now I´m rebuilding it.
I have an original AMDS System for better testing. I did all the testings regarding Canbus, checked resistance (60 ohms), tested short circuit
to ground and to power. DIM is not working, I only could see the engine light. Swapped the DIM, no change. Checked +/- on the DIM plug, checked
short to +/-, nothing. Could access every module by AMDS except DIM, tested with an oscilloscope the Canbus, voltage and communication seems okay for both circuits.
swapped the BCM, nothing.
Does anybody of you guys have an idear what I could do next ?

Thanks to all

 

Where are you taking the resistance and scope readings from?

 

Are you sure your CEM works ok? It should send CAN messages waking up the DIM. Do you have CAN analyser to see if the CEM sends anything to DIM? DIM can be initiated with CEM frames on Low Speed CAN: EC353BC 01 00 00 00 BD 8E FF 7A or EC353BC 01 00 00 00 BD 98 00 85. I would check if you see CAN signals directly on DIM socket, it seems to me you have CAN lines broken between DIM and CEM. To start the engine DIM should send matching VIN, otherwise ECM will not crank.

 

Hi V12AM,

I was measuring on the OBD port and I used the chassis of the vehicle as ground. Furthermore I have tested CAN BUS communication with an simple OBD testing tool (CTB007)
I have measured HI CAN and LOW CAN on the same time.

 

Hi chrzesm,

you are right, the DIM works on the CAN BUS LOW, and I made a continuity test on both lines (marked red) between CEM and the DIM (green plug)
which was okay,

 

Hi,

furthermore I have the error "fuel system disabled", might have something to do because of the DIM issue.

What I did in the meanwhile:

Checked the fuel pump: OK
Checked the fuel pressure (in range): OK
Checked the fuel ECU, behind subwoofer, driver seat: OK
Checked the pyro fuse: OK






Had a strange issue when I disconnected the "INFOTAINMENT CONTROL MODULE" (behind center dashboard) after I turned on the ignition some modules came back online.
But I couldn´t replicate this behaviour, maybe it was just a bug from the software, I don´t know.

 

This thread is like a mainline injection into my veins.... Thank you for posting!

 

P1233 - The fuel pump driver module is offline. There's a fuel pump monitor signal from the pump driver to the PCM. Either the fuel pump driver module is not getting power or the monitor signal is not getting back to the PCM.

The DIM lives on and terminates the end of both LS and HS CAN bus. Pin 2/3 is the low speed canbus. The other end is terminated by the airbag module. Pin 4/5 is the high speed canbus. The other end is terminated by the ABS module.

 

I would suggest to check if you can see CAN waives between pin 2 and 3 on the green plug. The DIM should wake up as soon as it has power supply and proper Low CAN communication with CEM. Engine MIL light is completely isolated and powered from ECM, so it does not say if DIM is properly powered. So you should see: GND - pin 30, +12V - pin 1, CAN signal - pins 2, 3.

 

You need to fix the DIM issue first as DIM sends its VIN data. ECM will not activate the engine components until the VIN data from DIM, CEM match with ECM.

 

Hi chrzesm,
could it be that the ECM are faulty ?