2009 Suburban 4x4 with 5.3 engine would not start. Starter would not move. New strater does not work also. We checked all wirings and found problem was ABS System. When modulator was unpugged engine starts and everyxthing is working perfect exept naturally ABS. What to do? Replace ABS Relais and Modulator? Vehicle is in Germany and GM people do not know much.

 

any communication codes when the module is plugged in? It may be bringing down the CAN Bus communication.

 

There was a service bulletin and I am not sure if your model year is listed. It was regarding the main ground cable to frame as the issue.

 

Turning the key to Ignition: All lights go on as normal
Turning the Key to Start: All lights go out. Starter does not turn
If ABS Modul is unplugged Engine runs, but you cannot move
but if you connect Modul with running engine the engine stops already.
There are no communication codes
Our tech means may be water went into the module. And we should replace the whole unit
Ground connections are all checked. Looks like O.K.
Thank you for help. Any other idea?

 

1-what are you using for a scan tool?
2-can you communicate with the abs module, pcm. Are there any modules you can't communicate with?

 

Shop is GM Shop and uses the original GM computer. You can not communicate with any module. Nothing works.
Technician opened the Module and found no water in it. Was absolute dry. He means there could be an internal shortage.
But is not sure.
We tried again to move the vehicle. ABS unconnected engine starts. But if you connect ABS with running engine you cannot shift the gears.
All ground connections are O.K.

 

if you can't communicate with any module; you have a CAN bus problem. the bus is daisy chained together. the shop should be checking the CAN + and Can - voltages and then disconnecting the battery and ohm checking the CAN bus ....you should have 60 ohm terminating resistance when measured at the dlc. if your getting 120 ohms find out the modules that have the terminating resistors, start in the middle of the bus and check each side....work your way back to the module that have the terminating resistors.

 

Shop is not able to meassure the Ohm at the DLC. They do not know which pins they should use. Can you send a picture of the DLC and mark the Pins?
Is the part AC20896914 Control Module part of the CanBus and is located on top of AC208969012 Modulator Valve?
If so, this part may have an internal short?
Regrads from Germany
Hermann

 

pin 14 and 6 at the dlc
DLC 2

the data bus lines run through every module that is part of the bus circuit...the abs module is one of them.

can the shop not print off a wiring diagram of the data lines...any vehicle repair info system will have it.

do they not have gm dealers in germany...if they do, go there. the current shop is in over their head.