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Hi everyone just trying to fix an issue I've been having with my SDM unit on my 1998 C5, the DIC is saying"58 SDM NO COMM."The air bad light flashes a few times on start up and then stays on.this issue seems to of appeared after i swapped out my orignal 1998 IPC and guages to a 2002 C5 model.I have been doing alot of interior work and what not aswell with my C5 so I could of accidentally bumped something too, but shouldnt my 98 SDM unit be compatible with a 2002 IPC?are the SDM units the same part number?how should I look at fixing this issue?will I need a 2002 SDM unit aswell? Thanks! (to add to this I had to replace my orignal IPC due to isolated water damage)
Here is the schematic of your 98 SDM module . The SDM module is for some reason routed to pin 9 of the DLC connector(OBD port) on the 97/98 cars .
It is not connected to the serial line at all (Connector pin 2) See diagrams below .
The second last diagram show how the SDM is connected to the serial line (connector 2) on a 1999 car .
To be able to read codes/values of the SDM module I think you have to temporarely has to make the connector between port 2 of the OBD port and the SDM module it self
On the 99-05 cars are the SDM connected to the port 2 of the OBD2 connector shown below
Here is the schematic of your 98 SDM module . The SDM module is for some reason routed to pin 9 of the DLC connector(OBD port) on the 97/98 cars .
It is not connected to the serial line at all (Connector pin 2) See diagrams below .
The second last diagram show how the SDM is connected to the serial line (connector 2) on a 1999 car .
To be able to read codes/values of the SDM module I think you have to temporarely has to make the connector between port 2 of the OBD port and the SDM module it self
On the 99-05 cars are the SDM connected to the port 2 of the OBD2 connector shown below
Thanks !!…chart is for a ‘97…how would you diagnose this specifically??
The diagnosis is in the details. The OP installed an IPC from a 2002, which is looking for serial communication from the SDM....which is not there by design on a 97-98.
Thanks !!…chart is for a ‘97…how would you diagnose this specifically??
Originally Posted by lucky131969
The diagnosis is in the details. The OP installed an IPC from a 2002, which is looking for serial communication from the SDM....which is not there by design on a 97-98.
Originally Posted by ncali
The OP installed an IPC from a 2002, which is looking for serial communication from the SDM....which is not there by design on a 97-98.
so if I understand correctly, if one has a `98 IPC and replaces it with one newer, this no comm condition will appear
thanks all! So abit of progress with this issue, I have relocated the airbag light to the middle of the tach gauge which I later found out I had to do when upgrade the IPC but the airbag light is still no, but it doesn't flash it just turns on and stays on during start up. Any idea why? And how to reset it?
SDM no comm. Issue after new IPC
